NCERT Class 11 Practical Geography Chapter 8: Weather Instruments, Maps and Charts

Weather & Forecast

• Weather: The condition of the atmosphere at a given place and time with respect to atmospheric pressure, temperature, humidity, precipitation, cloudiness and wind. These factors are known as weather elements.
• Weather Forecast: Prediction with a reasonable amount of certainty about the conditions of weather that would prevail in the coming 12 to 48 hours in a certain area.
• The Indian Meteorological Department (IMD) was established in 1875, with its headquarters at Calcutta. The IMD headquarters are presently located at New Delhi

Weather Observations – 3 Levels

The World Meteorological Organization (WMO) , a specialized agency of the United Nations, coordinates these observations

Spaced Based Observations (E. G. INSAT)

Weather satellites make comprehensive and large-scale observations of different meteorological elements at the ground level as well in the upper layers of the atmosphere. The geo-stationary satellites provide space-based observations about weather conditions

Surface Observations – IMD Class 1 (Highest Category)

• A typical surface observatory has instruments for measuring and recording weather elements like temperature (maximum and minimum) , air pressure, humidity, clouds, wind, and rainfall. Specialized observatories also record elements like radiation, ozone atmospheric trace gases, pollution, and atmospheric electricity. These observations are taken all over the globe at fixed times of the day
• Observations are taken in these observatories normally at 00, 03, 06, 09, 12, 15,18, 21 hours (Greenwich Mean Time) around the globe.
• For logistics – some observations are limited on daily numbers

Stevenson Screen: Thermometers

• The Stevenson screen is designed to protect thermometers from precipitation and direct sunlight while allowing air to circulate freely around them. It is made from wood with louvered sides to allow free and even flow of air. It is painted white to reflect radiation. It stands on four legs and is about 3 feet 6 inches above the level of the ground. The legs must be sufficiently rigid and be buried sufficiently in the ground to prevent shaking.
• The front panel is hinged at the bottom to form a door, which allows for maintenance and reading of the thermometers. The door of Stevenson screen is always towards the north in the northern hemisphere and towards the south in the southern hemisphere because direct sunrays also affect mercury. The purpose of the Stevenson screen is to create a uniform temperature enclosure that closely represents the same temperature as the air outside

Maximum & Minimum Thermometers

• Thermometer is used to measure air temperature. Most thermometers are in the form of a narrow closed glass tube with an expanded bulb at one end. The bulb and the lower part of the tube are filled with liquid such as mercury or alcohol. Before the other end is sealed off, the air in the tube is released by heating it.
• Celsius – melting ice is marked 0 degree C and that of boiling water as 100 degree C, and the interval between the two is divided into 100 equal parts
• On the Fahrenheit thermometer, the freezing and boiling points of water are graduated as 32 degree F and 212 degree F respectively
• While the maximum thermometer and minimum thermometer are used to measure the air temperature, the dry bulb and the wet bulb thermometers are used to determine the humidity in the air. A set of these thermometers is kept in the Stevenson Screen.
• The maximum thermometer is designed to record the highest temperature during a day. As the temperature increases, the mercury moves up into the tube; however, as the mercury cools, it cannot move downwards because of a constriction in the tube. It must be reset again to bring it down
• Minimum thermometer – In this thermometer, alcohol is used in place of mercury. When the temperature decreases, the metal pin in the tube goes down and strikes at the minimum temperature.

Wet & Dry Bulb Thermometers

• The dry bulb and wet bulb thermometers are two identical thermometers fixed to a wooden frame. The bulb of the dry thermometer is kept uncovered and is exposed to the air while the bulb of the wet bulb thermometer is wrapped up with a piece of wet muslin, which is kept continuously moist by dipping a strand of it into a small vessel of distilled water. The evaporation from the wet bulb lowers its temperature.
• Dry bulb readings are not affected by the amount of water vapour present in the air, but the wet bulb readings vary with it since the rate of evaporation is dependent upon the amount of water vapour present in the air. The greater the humidity in the air, the slower the rate of evaporation and hence, the difference between the readings of the dry bulb and wet bulb will be small. On the other hand, when the air is dry, the evaporation from the surface of the wet bulb is rapid, which would lower its temperature and the difference between the two readings would be larger.
• Difference of the readings of the dry bulb and the wet bulb thermometers determines the state of the atmosphere with regard to its humidity.
• The larger the difference, the more arid is the air.

Wind Vane

• Wind vane is a device used to measure the direction of the wind. The wind vane is a lightweight revolving plate with an arrowhead on one end and two metal plates attached to the other end at the same angle. This revolving plate is mounted on a rod in such a manner that it is free to rotate on a horizontal plane
• The arrow always points towards the direction from which the wind blows

Rain Gauge

• The amount of rainfall is measured with the help of a rain gauge. The rain gauge consists of a metal cylinder on which a circular funnel is fitted. The diameter of the funnel՚s rim is normally 20 cm
• Normally, rainfall is measured in the units of millimetres or centimetres. Snow is also measured in a similar manner by turning it into liquid form
  • Temperature- Thermometer 
  • Atmospheric Pressure -Barometer -Millibars
  • Wind (Direction) -Wind Vane -Cardinal points
  • Wind (Velocity) – Anemometer -Km/hr
  • Rainfall -Rain Gauge- mm/cm

Barometer

• The air around us has weight, and it exerts great pressure on the earth՚s surface. At the sea level, under normal conditions, the pressure of air is 1.03 kg per square centimetre. Due to constant movement of air, change in temperature and variation in its vapour content, the weight of the air changes continuously with time and place.
• Mercury barometer, aneroid barometer and barographs. The unit of measurement is in the millibar.
• Mercury barometer is an accurate instrument and is used as a standard. In it the atmospheric pressure of any place is balanced against the weight of a column of mercury in an inverted glass tube
• The mercury will flow out of the tube into the cup and stand at a definite height above the level of the liquid in the cup. This is because the weight of the column of the mercury in the tube, above the surface of the mercury in the cup, is balanced by the weight of the air column of an indefinite height exerted as pressure upon an equal cross-section of the liquid surface. The height of the column of mercury in the tube, therefore, becomes the measure of the pressure of air.
• Aneroid barometer gets its name from the Greek work, aneros (a- ‘not’ , neros – ‘moisture’ , meaning without liquid) It is a compact and portable instrument. It consists of a corrugated metal box made up of a thin alloy, sealed completely, and made airtight after partial exhaustion of air. It has a thin flexible lid, which is sensitive to changes of pressure.
• As the pressure increases, the lid is pressed inward, and this, in turn, moves a system of levers connected to a pointer, which moves clockwise over the graduated dial and gives higher reading. When the pressure decreases, the lid is pushed outward and the pointer moves counter clockwise, indicating lower pressure
• Barograph works on the principle of aneroid barometer. There are a number of vacuum boxes placed one above the other so that the displacement is large. A system of levers magnifies this movement, which is recorded by a pen on a paper attached to a rotating drum. The readings of a barograph are not always accurate, and therefore, they are standardized by comparing them with a mercury barometer reading.

Weather Maps, Charts & Symbols

• Weather Maps: A weather map is the representation of weather phenomena of the earth or a part of it on a flat surface. It depicts conditions associated with different weather elements such as temperature, rainfall, sunshine and cloudiness, direction and velocity of winds, etc. on a particular day. Such observations being taken at fixed hours are transmitted by code to the forecasting stations. The central office keeps a record of the observations, which forms the basis for making a weather map. The upper air observations, which are procured from hill stations, aeroplanes, pilot balloons, etc. , are plotted separately
• Meteorological observatories transmit the data to the Central Observatory at Pune twice a day. Data is also collected on ships plying on the Indian seas. A good progress has been made in the field of weather forecasting and observation with the establishment of weather observatories in Antarctica, the International Indian Ocean Expedition, and the launching of rockets and weather satellites.
• Weather Charts: The data received from various weather observatories are in plenty and detailed. As such, they cannot be incorporated in one single chart unless the coding designed to give the economy of expression is used. These are called synoptic weather charts and the codes used are called meteorological symbols. Weather charts provide the primary tools for weather forecasting. They help in locating and identifying different air masses, pressure systems, fronts, and areas of precipitation.
• WEATHER SYMBOLS: The messages received from all the observatories are plotted on the map using weather symbols standardized by the World Meteorological Organization and the National Weather Bureaus.

Isobars, Isotherms, Isohyets, Isohels, Isonephs

Isobars: Lines connecting places of equal air pressure.

Isotherms: Lines connecting places of equal temperature.

Isohyets: Lines connecting places of equal amount of rainfall over a given period.

Isohels: Lines connecting places of same mean daily duration of sunshine.

Isonephs: Lines connecting places of same mean value of cloud cover

Weather Map Interpretation

NCERT Class 11 Chapter 7 Practical Geography Introduction to Remote Sensing

Unlike aerial photo which observe similar to human eyes.

Remote sensing can go much beyond & react to much wider range of radiations reflected/emitted, absorbed and transmitted by all object surfaces at a temperature above 0 Kelvin () .

The term remote sensing was first used in the early 1960s. Later, it was defined as the total processes used to acquire and measure the information of some property of objects and phenomena by a recording device (sensor) that is not in physical contact with the objects and phenomena in study

• Absorptance: The ratio of the radiant energy absorbed by a substance to the energy it receives.
• Band: The specific wavelength interval in the electromagnetic spectrum.
• Digital image: An array of digital numbers (DN) arranged in rows and columns, having the property of an intensity value and their locations.
• Digital Number: An intensity value of a pixel in a digital image.
• Digital Image Processing: The numerical manipulation of DN values for extracting information about the phenomena of the surface they represent.
• Electromagnetic Radiation (EMR) : The Energy propagated through a space or a medium at a speed of light.
• Electromagnetic Spectrum: The continuum of EMR that ranges from short wave high frequency cosmic radiations to long wavelength low frequency radio waves.
• False Colour Composite (FCC) : An artificially generated colour image in which blue, green and red colours are assigned to the wavelength regions to which they do not belong in nature. For example, in standard a False Colour Composite blue is assigned to green radiations (0.5 to ) , green is assigned to red radiations (0.6 to  and red is assigned to Near Infrared radiation (0.7 to ) .
• Gray scale: A medium to calibrate the variations in the brightness of an image that ranges from black to white with intermediate grey values.
• Image: The permanent record of a scene comprising of natural and synthetic features and activities, produced by photographic and non – photographic means.
• Scene: The ground area covered by an image or a photograph.
• Sensor: Any imaging or non – imaging device that receives EMR and converts it into a signal that can be recorded and displayed as photographic or digital image.
• Reflectance: The ratio of the radiant energy reflected by a substance to the energy it receives.
• Spectral Band: The range of the wavelengths in the continuous spectrum such as the green band ranges from 0.5 to  and the range of NIR band 0.7 to .

Stages in Remote Sensing

• Source of Energy (sun/self-emission) – artificially by flashguns and energy beams in radar (radio detection and ranging)
• Transmission of energy from the source to the surface of the earth – propagates at speed of light called Electromagnetic Radiation (EMR) – vary in size and frequency
• Interaction of energy with the earth՚s surface
• Propagation of reflected/emitted energy through atmosphere – atmosphere comprises of gases, water molecules, and dust particles. The energy reflected from the objects comes in contact with the atmospheric constituents and the properties of the original energy are modified. , H, and  molecules absorb energy in the middle infrared region; the dust particles scatter the blue energy. Hence, the energy that is either absorbed or scattered by the atmospheric constituents never reaches to sensor placed onboard a satellite and the properties of the objects carried by such energy waves are left unrecorded
• Detection of the reflected/emitted energy by the sensor
• Conversion of energy received into photographic/digital form of data – Digital image comprises digital numbers that are arranged in rows and columns. These numbers may also be converted into an analogue (picture) form of data product. The sensor onboard an earth-orbiting satellite electronically transmits the collected image data to an Earth Receiving Station located in different parts of the world. In India, one such station is located at Shadnagar near Hyderabad
• Extraction of the information contents from the data products – errors are eliminated in data collected, image is corrected – digital image processing is done
• Conversion of information into Map/Tabular forms – converted into different layers of thematic maps (use quantitative measures as well)

Based on the size of the waves and frequency, the energy waves are grouped into Gamma, X – rays, Ultraviolet rays, visible rays, Infrared rays, Microwaves, and Radio waves. Each one of these broad regions of spectrum is used in different applications. However, the visible, infrared and microwave regions of energy are used in remote sensing

Interaction of Energy with the Earth՚s Surface: The propagating energy finally interacts with the objects of the surface of the earth. This leads to absorption, transmission, reflection, or emission of energy from the objects. We all know that all objects vary in their composition, appearance forms, and other properties. Hence, the objects՚ responses to the energy they receive are also not uniform.

For example, a fresh water body absorbs more energy in the red and infrared regions of the spectrum and appears dark/black in a satellite image whereas turbid water body reflects more in blue and green regions of spectrum and appears in light tone

Spectral Signatures Are Important

• Detection of Reflected/Emitted Energy by the Sensor: The sensors recording the energy that they receive are placed in a near – polar sun synchronous orbit at an altitude of 700 – 900 km. These satellites are known as remote sensing satellites (e. g. Indian Remote Sensing Series) . As against these satellites, the weather monitoring and telecommunication satellites are placed in a Geostationary position (the satellite is always positioned over its orbit that synchronizes with the direction of the rotation of the earth) and revolves around the earth (coinciding with the direction of the movement of the earth over its axis) at an altitude of nearly 36,000 km (e. g. INSAT series of satellites)
• Sun Synchronous – 700 – 900 km, cover  N to , earth resource applications
• Geostationary – 36000 km, cover  ^rdof the globe, orbital period is 24 hours, used in Telecommunication and weather monitoring
• The images so acquired by space-borne sensors are in digital format as against the photographic format obtained through a camera-based system

Images of Himalayas and Northern Indian Plain by IRS Satellite taken in May (Left) and November (Right) show differences in the types of vegetation. The red patches in May image refer to Coniferous vegetation. In November image the additional red patches refer to deciduous plants and the light red colour is related to the crops

Satellite Multispectral Scanners

• A sensor is a device that gathers electromagnetic radiations, converts it into a signal, and presents it in a form suitable for obtaining information about the objects under investigation. Based upon the form of the data output, the sensors are classified into photographic (analogue) and non – photographic (digital) sensors
• A photographic sensor (camera) records the images of the objects at an instance of exposure. On the other hand, a non – photographic sensor obtains the images of the objects in bit-by-bit form. These sensors are known as scanners.
• MultiSpectral Scanners (MSS) are used as sensors. These sensors are designed to obtain images of the objects while sweeping across the field of view. A scanner is usually made up of a reception system consisting of a mirror and detectors. A scanning sensor constructs the scene by recording a series of scan lines. While doing so, the motor device oscillates the scanning mirror through the angular field of view of the sensor, which determines the length of scan lines and is called swath. It is because of such reasons that the mode of collection of images by scanners is referred bit – by – bit. Each scene is composed of cells that determine the spatial resolution of an image. The oscillation of the scanning mirror across the scene directs the received energy to the detectors, where it is converted into electrical signals. These signals are further converted into numerical values called Digital Number (DN Values) for recording on a magnetic tape.
• Whiskbroom (Across track) Scanners: The whiskbroom scanners are made up of a rotating mirror and a single detector. The mirror is so oriented that when it completes a rotation, the detector sweeps across the field of view between  and  to obtain images in a large number of narrow spectral bands ranging from visible to middle infrared regions of the spectrum. The total extent of the oscillating sensor is known as the Total Field of View (TFOV) of the scanner. While scanning the entire field, the sensor՚s optical head is always placed at a particular dimension called the Instantaneous Field of View (IFOV) .
• Push broom (Along track) Scanners: The push broom scanners consist of a number of detectors, which are equivalent to the number obtained by dividing the swath of the sensor by the size of the spatial resolution. For example, the swath of High Resolution Visible Radiometer – 1 (HRVR – 1) of the French remote sensing satellite SPOT is 60 km and the spatial resolution is 20 metres. If we divide  metres, we get a number of 3000 detectors that are deployed in SPOT HRV – 1 sensor. In push broom scanner, all detectors are linearly arrayed and each detector collects the energy reflected by the ground cell (pixel) dimensions of 20 metres at a nadir՚s view.

Satellite Sensors Types of Resolution

Types of Sensor Resolution

• Temporal – how many image in a given time
• Spectral – shades can be recorded – frequency and sensitivity – quantization Data can be 0 to 16 or can be 0 to 255 – Color – The principles in obtaining such images is the extension of the dispersion of light in nature resulting in the appearance of the ‘rainbow’ and the use of prism in the lab. Strong absorption properties of fresh water in band 4 (Infrared) and mixed strong reflectance in band 2 (green) by dry surfaces
• Radiometric resolution corresponds to the sensitivity of a sensor, i.e.. its ability to measure and to enable distinction within the same spectral band of differences (intensity or energy)
• Spatial – distance – With an increasing resolution the identification of even smaller object surfaces become possible

Band 2: 0.52 to 0.59 

Band 3: 0.62 to 0.68 

Band 4: 0.77 to 0.86 

Dispersion of Light (The principle that is utilized in obtaining Multispectral Images)

The overall mechanism of obtaining images in a number of bands derives strength from the principle of the dispersion of light. You must have seen the rainbow. It is formed through a natural process of dispersion of light rays through water molecules present in the atmosphere. The same phenomena may be experimented by putting a beam of light at one side of a prism. At the other side of the prism, you may notice the dispersion of energy into seven colours that form white light

Elements of Image Interpretation

• Tone or color: smooth and dry object surfaces reflect more energy in comparison to the rough and moist surfaces. Healthy vegetation reflects strongly in the infrared region because of the multiple-layered leaf structure and appears in a light tone or bright red colour in standard false colour composite and the scrubs appear in greyish red colour. Similarly, a fresh water body absorbs much of the radiations received by it and appears in dark tone or black colour, whereas the turbid water body appears in light tone or light bluish colour in FCC due to mixed response shown by the water molecules as well as suspended sand particles
• Texture: dense residential areas in a large city form fine texture due to the concentration of the houses in a smaller area and the low-density residential areas produce a coarse texture. Similarly, in high-resolution images the sugarcane or millet plants produce coarse texture in comparison to the fine texture of rice or wheat plants. One can also notice the coarse texture in the images of scrubbed lands if compared with the fine texture of lush green evergreen forests.
• Size: It helps in distinctively identifying the industrial and industrial complexes with residential dwellings, stadium in the heart of the city with brick kilns at an urban fringe, size and hierarchy of the settlements
• Shape: railway line can be readily distinguished from a road due to its long continuous linearity in shape with gradual change in its course.
• Shadow: The shape of some of the objects is so typical that they could not be identified without finding out the length of the shadow they cast. For example, the Qutub Minar located in Delhi, minarets of mosques, overhead water tanks, electric or telephone lines, and similar features can only be identified using their shadow
• Pattern: planned residential areas with the same size and layout plan of the dwelling units in an urban area can easily be identified if their pattern is followed. Similarly, orchards and plantations produce arrangements of the same type of plants with uniform inter plant distances.
• Association: an educational institution always finds its association with its location in or near a residential area as well as the location of a playground within the same premises. Similarly, stadium, race course and golf course holds good for a large city, industrial sites along highway at the periphery of a growing city, and slums along drains and railway lines

Aerial Photographs Revision notes

• When we look to an object directly – horizontal perspective
• When we look below – birds eye view – aerial perspective
• The photographs taken from an aircraft or helicopter using a precision camera are termed aerial photographs.
• Aerial Camera: A precision camera specifically designed for use in aircrafts.
• Aerial Film: A roll film with high sensitivity, high intrinsic resolution power and dimensionally stable emulsion support.
• Aerial Photography: Art, science and technology of taking aerial photographs from an air-borne platform.
• Aerial Photograph: A photograph taken from an air-borne platform using a precision camera.
• Fiducial Marks: Index marks, rigidly connected at the central or corner edges of the camera body. When the film is exposed, these marks appear on the film negative.
• Forward Overlap: The common area on two successive photographs in the flight direction. It is usually expressed in per cent.
• Image Interpretation: An act of identifying the images of the objects and judging their relative significance.
• Nadir Point: The foot of the perpendicular drawn from the camera lens center on the ground plane.
• Principal Point: The foot of the perpendicular drawn from the camera lens center on the photo plane.
• Principal Distance: The perpendicular distance from the perspective center to the plane of the photograph.
• Perspective Centre: The point of origin (perspective center) of the bundle of light rays.
• Photogrammetry: The science and technology of taking reliable measurements from aerial photographs.

Uses of Aerial Photography

• development of photogrammetry and photo/image interpretation
• Photogrammetry: It refers to the science and technology of making reliable measurements from aerial photographs – precise measurement of length, breadth and height – creating and updating topographic maps
• Image Interpretation: It is an art of identifying images of objects and judging their relative significance – get qualitative information on land use and soil and analyses land use data
• India – started in 1920s for Agra; Irrawaddy Delta forests in 1923 – 24,
• Today, aerial photography in India is carried out for the entire country under the overall supervision of the Directorate of Air Survey (Survey of India) New Delhi.
• Three flying agencies, i.e.. Indian Air Force, Air Survey Company, Kolkata and National Remote Sensing Agency, Hyderabad as A, B and C respectively
• The procedure for indenting aerial photographs for educational purposes could be made with APFPS Party No. 73, Directorate of Air Survey, Survey of India, West Block IV, R. K. Puram, New Delhi.

Advantages of Aerial Photography

• Improved vantage point: Aerial photography provides a bird՚s eye view of large areas
• Time freezing ability: An aerial photograph is a record of the surface features at an instance of exposure – provide historical record
• Broadened Sensitivity: Our eyes perceive only in the visible region of the electromagnetic spectrum, i.e.. 0.4 to 0.7 μm whereas the sensitivity of the film ranges from 0.3 to 0.9 μm.
• Three Dimensional Perspective: Aerial photographs are normally taken with uniform exposure interval that enables us in obtaining stereo pair of photographs

Types of Aerial Photographs Based on the Position of the Cameral Axis

• Vertical Photographs: While taking aerial photographs, two distinct axes are formed from the camera lens center, one towards the ground plane and the other towards the photo plane.
• If such a deviation is within the range of plus or minus 3o, the near-vertical aerial photographs are obtained. Any photography with an unintentional deviation of more than 3o in the optical axis from the vertical axis is known as a tilted photograph.
• Low Oblique: An aerial photograph taken with an intentional deviation of 15° to 30° in the camera axis from the vertical axis is referred to as the low oblique photograph. In reconnaissance surveys.
• High Oblique: The high oblique are photographs obtained when the camera axis is intentionally inclined about 60° from the vertical axis

Types of Aerial Photographs Based on Scale

• Large Scale Photographs: When the scale of an aerial photograph is 1: 15,000 and larger
• Medium Scale Photographs: The aerial photographs with a scale ranging between 1: 15,000 and 1: 30,000
• Small Scale Photographs: The photographs with the scale being smaller than 1: 30,000
• Small area and try to zoom it – large scale map covers smaller area with greater detail and then from a colony to a city

Geometry of Aerial Photographs

• To understand the geometry of an aerial photograph, it is important to appreciate the orientation of the photograph with respect to the ground
• Parallel Projection: In this projection, the projecting rays are parallel but not necessarily perpendicular. The triangle ABC is projected on LL1 as triangle abc
• Orthogonal Projection: This is a special case of parallel projections with light source at infinity. Maps are orthogonal projections of the ground – here distances, angles or areas on the plane are independent of the elevation differences of the objects. Orthogonal projection where the projecting rays are perpendicular to the line LL1.
• Central Projection: The projecting rays Aa, Bb and Cc pass through a common point O, which is called the perspective Centre. The image projected by a lens is treated like a central projection as in aerial photographs. In an absolutely vertical flat terrain, the aerial photograph will be geometrically the same as the corresponding map of the area. However, because of the tilt of the photograph and relief variations of the ground photographed, an aerial photograph differs geometrically from the map of the corresponding area.
• vertical line (plumb line as indicated by the direction of gravity)
• For an oblique photograph, the angle between the camera axis and the plumb line is the tilt angle.
• The geometry of the positive and the negative planes are identical.

SP = distance b/w camera lens and negative plane = focal length

SP_G = distance b/w camera lens and ground = flying height

Aerial Photograph

• It is a central Projection.
• An aerial photograph is geometrically incorrect. The distortion in the geometry is minimum at the center and increases towards the edges of the photographs.
• The scale of the photograph is not uniform.
• Enlargement/reduction does not change the contents of the photographs and can easily be carried out.
• Aerial photography holds good for inaccessible and inhospitable areas.

Map

• It is an orthogonal Projection.
• A map is a geometrically correct representation of the part of the earth projected.
• The scale of the map is uniform throughout the map extent.
• Enlargement/reduction of the maps involves redrawing it afresh.
• The mapping of inaccessible and inhospitable areas is very difficult and sometimes it becomes impossible.
• Even vertical aerial photographs do not have a consistent scale unless they have been taken of a flat terrain. Aerial photographs need to be transformed from perspective view to the planimetric view before they can be used as map substitute. Such transformed photographs are known as orthophotos.
• In a perspective view, all light rays reflected from the Earth՚s surface pass through a single point at the center of the camera lens. A planimetric (plan) view looks as though every position on the ground is being viewed from directly above.
• A map cannot be directly traced out of an aerial photograph. The reason is that there is a basic difference in the planimetry (projection) and perspective of a map and an aerial photograph.
• Method 1: By Establishing Relationship Between Photo Distance and Ground Distance
• Method 2: By Establishing Relationship Between Photo Distance and Map Distance
• Method 3: By Establishing Relationship Between Focal Length (f) and Flying Height (H) of the Aircraft
• Scale is the ratio of a distance on an aerial photograph the distance between the same two places on the ground in the real world expressed as RF. Scale determines what objects would be visible, the accuracy of estimates and how certain features will appear
• Method 1: By Establishing Relationship Between Photo Distance and Ground Distance scale of an aerial photograph will be measured as a ratio of the two, i.e.. Dp/Dg

Question: The distance between two points on an aerial photograph is measured as 2 cm. The known distance between the same two points on the ground is 1 km. Compute the scale of the aerial photograph (Sp) .

Sp = Dp: Dg

= 2 cm: 1 km

= 2cm: 1 x 100,000 cm

= 1: 100,000/2 = 50,000 cm

= 1 unit represents 50,000 units

Therefore, Sp = 1: 50,000

Scale of Aerial Photograph

• Method 2: By Establishing Relationship Between Photo Distance and Map Distance, distances between two points identifiable both on a map and the aerial photograph enable us to compute the scale of the aerial photograph (Sp) . The relationship between the two distances may be expressed as under: (Photo scale: Map scale) = (Photo distance: Map distance)
• We can derive, Photo scale (Sp) = Photo distance (Dp) : Map distance (Dm) x Map scale factor (msf)

Question: The distance measured between two points on a map is 2 cm. The corresponding distance on an aerial photograph is 10 cm. Calculate the scale of the photograph when the scale of the map is 1: 50,000.

Sp = Dp: Dm x msf

Or = 10 cm: 2 cm x 50,000

Or = 10 cm: 100,000 cm

Or = 1: 100,000/10 = 10,000 cm

Or = 1 unit represents 10,000 units

Therefore, Sp = 1: 10,000

• Method 3: By Establishing Relationship Between Focal Length (f) and Flying Height (H) of the Aircraft
• Focal Length (f) : Flying Height (H) = Photo distance (Dp) : Ground distance (Dg)

Question: Compute the scale of an aerial photograph when the flying height of the aircraft is 7500m and the focal length of the camera is 15cm.

Sp = f: H

Or Sp = 15 cm: 7,500 x 100 cm

Or Sp = 1: 750,000/15

Therefore, Sp = 1: 50,000

Marginal Information Given on Vertical Aerial Photographs

⚹ 793 is a Photo Specification number maintained by the 73 APFPS Party of the Survey of India. B is the Flying Agency that carried out the present photography (In India three flying agencies are officially permitted to carry out aerial photography. They are the Indian Air Force, the Air Survey Company, Kolkata and the National Remote Sensing Agency, Hyderabad, identified on the aerial photographs as A, B and C respectively) , 5 is the strip number and 23 is the photo number in strip 5.

NCERT Class 11 Chapter 5 Practical Geography Topographical Maps

Topographical Maps

• These maps show important natural and cultural features such as relief, vegetation, water bodies, cultivated land, settlements, and transportation networks, etc. These maps are prepared and published by the National Mapping Organization of each country. For example, the Survey of India prepares the topographical maps in India for the entire country. The topographical maps are drawn in the form of series of maps at different scales. Hence, in the given series, all maps employ the same reference point, scale, projection, conventional signs, symbols, and colours.
• Topographic Map: A map of a small area drawn on a large-scale depicting detailed surface features both natural and manmade. Relief in this map is shown by contours.

Topographical Maps in India in 2 Series

• India and Adjacent Countries Series: the Survey of India prepared topographical maps under India and Adjacent Countries Series until the coming into existence of Delhi Survey Conference in 1937. Henceforth, the preparation of maps for the adjoining countries was abandoned and the Survey of India confined itself to prepare and publish the topographical maps for India as per the specifications laid down for the International Map Series of the World. However, the Survey of India for the topographical maps under the new series retained the numbering system and the layout plan of the abandoned India and Adjacent Countries Series. The topographical maps of India are prepared on 1: 10,00, 000,1: 250,000, 1: 1,25, 000,1: 50,000 and 1: 25,000 scale providing a latitudinal and longitudinal coverage of  and , respectively.
• International Map Series of the World: Topographical Maps under International Map Series of the World are designed to produce standardized maps for the entire World on a scale of 1: 10,00, 000, and 1: 250,000.
• The study of topographical maps is simple. It requires the reader to be acquainted with the legend, conventional sign, and the colours shown on the sheets.

• The Survey of India is India՚s central engineering agency in charge of mapping and surveying. Set up in 1767 to help consolidate the territories of the British East India Company It is one of the oldest Engineering Departments of the Government of India. The Survey of India՚s distinguished history includes the handling of the mammoth Great Trigonometric Survey under William Lambton and George Everest
• Among the many accomplishments of the Survey were the demarcation of the British territories in India and the measurement of the height of the Himalayan giants: Everest, K2, and Kanchenjunga. The Great Trigonometrical Survey of India started on 10 April 1802 with the measurement of a baseline near Madras. The East India Company thought that this project would take about 5 years but eventually it took more than 60 years, draining the profits of the Company, so much so it was brought under the Crown after 1857

• Toposheet number, state, district, latitude, longitude
• Legend sheet, index to sheet, map scale, district outline, legend
• National Map Policy: To provide, maintain and allow access and make available the National Topographic Database (NTDB) of the SOI conforming to national standards. To promote the use of geospatial knowledge and intelligence through partnerships and other mechanisms by all sections of the society and work towards a knowledge-based society.
• Two Series Of Maps – DSM Defense Series Maps (DSMs) – These will be the topographical maps (on Everest/WGS-84 Datum and Polyconic/UTM Projection) on various scales (with heights, contours, and full content without dilution of accuracy) . These will mainly cater for defense and national security requirements. This series of maps (in analogue or digital forms) for the entire country will be classified, as appropriate, and the Ministry of Defense will formulate the guidelines regarding their use.
• Two Series Of Maps – OSM Open Series Maps (OSMs) for supporting development activities in the country. OSMs shall bear different map sheet numbers and will be in UTM Projection on WGS-84 datum. Each of these OSMs (in both hard copy and digital form) will become “Unrestricted” after obtaining a one-time clearance of the Ministry of Defense. SOI will ensure that no civil and military Vulnerable Areas and Vulnerable Points (VA՚s/VP՚s) are shown on OSMs
• National Topographical Data Base (NTDB) NTDB in analogue and digital forms consisting of following data sets: National Spatial Reference Frame, National Digital Elevation Model, National Topographical Template, Administrative Boundaries, and Toponomy (place names) . Both the DSMs and OSMs will be derived from the NTDB

• Representative Fraction (RF) : It is the ratio between the distances on the map to its corresponding distance on actual ground. The RF on this map is 1: 50,000.
• Scale: Scale is the ratio between the distance of any two points on the map and the actual distance of the same points on the ground. The scale of the given map extract is 2 cm: 1 km or 1: 50,000.
• Contour: Contours are imaginary lines drawn on maps, joining all places with the same height above sea level.
• Contour Interval: The interval between two consecutive contours is called contour interval.
• Index Contour: Contour lines are thickened at regular intervals to make it easier to read contours. For example at every 100 mts, the contour line is made darker. The darker lines are called Index Contours.
• Triangulated Height: It is the height of a place which has been calculated using trigonometry, represented by a small triangle e. g. 
• Spot Height: The height of random places between contours shown with a dot. Eg – 0.425
• Bench Mark: Height of a place actually marked on a stone pillar, rock or shown on a building as a permanent reference. It is written as BM 200 m.
• Relative Height: Relative height is the height of a feature with reference to the height of the surrounding land and NOT to sea level. It is represented by the height with a small ‘r’ e. g. – 12r.
• Mixed Forest: A forest with more than two varieties of trees growing in close proximity to each other.
• Open Jungle: A forest where trees are widely scattered
• Dense Jungle: A forest where trees grow very close to each other
• OPEN SCRUB: Scrub is a vegetation found in regions with less than 100 cm of rainfall. Therefore, it indicates a dry region.
• Embankment: They are raised rock or soil filled constructions on which roads/railway tracks are built. Also made near tanks and rivers to prevent flooding
• Form Lines: Form lines are contour lines, but show only approximate heights above sea level as they are used to indicate the elevations of the area, which are not accessible for proper survey. Hence, they are drawn as broken lines and are called ‘form lines’ .
• Q. C. Q. D. , OC, OD, PQ, ETC: These are alphabetical codes used to represent the biggest grid sq. of 10,000 square kms

Methods of Relief Representation

• Methods of Relief Representation: The earth՚s surface is not uniform and it varies from mountains to hills to plateaus and plains. The elevation and depressions of the earth՚s surface are known as physical features or relief features of the earth. The map showing these features is called a relief map.
• A number of methods have been used to show the relief features of the Earth՚s surface on maps, over the years. These methods include hachure, hill shading, layer tints, benchmarks and spot heights and contours. However, contours and spot heights are predominantly used to depict the relief of an area on all topographical maps.
• Settlements, buildings, roads, and railways are important cultural features shown on topographical sheets through conventional signs, symbols, and colours.
• Four types of rural settlements may be identified on the map
  • Compact
  • Scattered
  • Linear
  • Circular
• Similarly, urban centres may also be distinguished as
  • Cross-road town
  • Nodal point
  • Market centre
  • Hill station
  • Coastal resort centre
  • Port
  • Manufacturing centre with suburban villages or satellite towns
  • Capital town
  • Religious centre
• Various factors determine the site of settlements like
  • Source of water
  • Provision of food
  • Nature of relief
  • Nature and character of occupation
  • Defence
• Density of settlement is directly related to food supply. Sometimes, village settlements form alignments, i.e.. they are spread along a river valley, road, embankment, and coastline, – and these are called linear settlements.
• In the case of an urban settlement, a crossroad town assumes a fan-shaped pattern, the houses being arranged along the roadside, and the crossing being at the heart of the town and the main market place. In a nodal town, the roads radiate in all directions

Contours

• Contours are imaginary lines joining places having the same elevation above mean sea level. A map showing the landform of an area by contours is called a contour map.
• Earlier, ground surveys and levelling methods were used to draw contours on topographical maps. However, the invention of photography and subsequent use of aerial photography have replaced the conventional methods of surveying, levelling and mapping. Henceforth, these photographs are used in topographical mapping.
• Contours are drawn at different vertical intervals (VI) , like 20,50, 100 metres above the mean sea level. It is known as contour interval. It is usually constant on a given map. It is generally expressed in metres. While the vertical interval between the two successive contour lines remains constant, the horizontal distance varies from place to place depending upon the nature of slope. The horizontal distance, also known as the horizontal equivalent (HE) , is large when the slope is gentler and decreases with increasing slope gradient.

• Contours: Imaginary lines joining all the points of equal elevation or altitude above mean sea level. They are also called “level lines.”
• Contour Interval: Interval between two successive contours. It is also known as vertical interval, usually written as V. I. Generally, it is constant for a given map.
• Cross-section: A side view of the ground cut vertically along a straight line. It is also known as a section or profile.
• Hachures: Small straight lines drawn on the map along the direction of maximum slope, running across the contours. They have given an idea about the differences in the slope of the ground.
• The slopes can broadly be classified into gentle, steep, concave, convex and irregular or undulating. The contours of different types of slopes show a distinct spacing pattern.
• Gentle Slope – When the degree or angle of slope of a feature is very low, the slope will be gentle. The contours representing this type of slope are far apart.
• Steep Slope – When the degree or angle of slope of a feature is high and the contours are closely spaced, they indicate steep slope.

Steps for Drawing a Cross-Section

The following steps may be followed to draw cross-sections of various relief features from their contours:

• Draw a straight line cutting across the contours on the map and mark it as AB.
• Take a strip of white paper or graph and place its edge along the AB line.
• Mark the position and value of every contour that cuts the line AB.
• Choose a suitable vertical scale, eg  cm = 100 metres, to draw horizontal lines parallel to each other and equal to the length of AB. The number of such lines should be equal or more than the total contour lines.
• Mark the appropriate values corresponding to the contour values along the vertical of the cross-section. The numbering may be started with the lowest value represented by the contours.
• Now place the edge of the marked paper along the horizontal line at the bottom line of the cross-section in such a way that AB of the paper corresponds to the AB of the map and mark the contour points.
• Draw perpendiculars from AB line, intersecting contour lines, to the corresponding line at the cross-section base.
• Smoothly join all the points marked on different lines at the cross section base.

• Concave Slope: A slope with a gentle gradient in the lower parts of a relief feature and steep in its upper parts is called the concave slope. Contours in this type of slope are widely spaced in the lower parts and are closely spaced in the upper parts.
• Convex Slope: Unlike concave slope, the convex slope is fairly gentle in the upper part and steep in the lower part. As a result, the contours are widely spaced in the upper parts and are closely spaced in the lower parts.

Landforms

• Conical Hill: It rises almost uniformly from the surrounding land. A conical hill with uniform slope and narrow top is represented by concentric contours spaced almost at regular intervals.
• Plateau: A widely stretched flat – topped high land, with relatively steeper slopes, rising above the adjoining plain or sea is called a plateau. The contour lines representing a plateau are normally close spaced at the margins with the innermost contour showing wide gap between its two sides.

• Valley: A geomorphic feature lying between two hills or ridges and formed because of the lateral erosion by a river or a glacier is called a valley.
• ‘V’ -shaped Valley: It resembles the letter V. A V-shaped valley occurs in mountainous areas. The lowermost part of the V – shaped valley is shown by the innermost contour line with very small gap between its two sides and the lowest value of the contour is assigned to it. The contour value increases with uniform intervals for all other contour lines outward.
• ‘U’ – shaped Valley: A U – shaped valley is formed by strong lateral erosion of glaciers at high altitudes. The flat wide bottom and steep sides makes it resemble the letter ‘U’ . The lowermost part of the U – shaped valley is shown by the innermost contour line with a wide gap between its two sides. The contour value increases with uniform intervals for all other contour lines outward.

• Gorge: In high altitudes, gorges form in the areas where the vertical erosion by river is more prominent than the lateral erosion. They are deep and narrow river valleys with very steep sides. A gorge is represented by very closely spaced contour lines on a map with the innermost contour showing small gap between its two sides.
• Spur: A tongue of land, projecting from higher ground into the lower is called a spur. It is also represented by Vshaped contours but in the reverse manner. The arms of the V point to the higher ground and the apex of ‘V’ to the lower ones.

• Cliff: It is a very steep or almost perpendicular face of landform. On a map, a cliff may be identified by the way the contours run very close to one another, ultimately merging into one.
• Waterfall and Rapids: A sudden and more or less perpendicular descent of water from a considerable height in the bed of a river is called a waterfall. Sometimes, a waterfall succeeds or precedes with a cascading stream forming rapids upstream or downstream of a waterfall. The contours representing a waterfall merge into one another while crossing a river stream and the rapids are shown by relatively distant contour lines on a map.

Interpretation

Marginal Information: It includes the topographical sheet number, its location, grid references, its extent in degrees and minutes, scale, the districts

• Relief – hill, plateau, plains, mountains
• Drainage – trellis, radial, ring
• Land use – vegetation, agriculture, services
• Transport and communication
• Settlement – rural and urban
• Occupation – lumbering, forestry, fishing

Interpretation Procedure

NCERT Class 11 Practical Geography Chapter 4 Map Projections

• Map projection – transform spherical surface into flat location
• Globe show directions and distances accurately
• Horizontal – parallels and vertical lines are longitudes
• Problems with globe – expensive, cannot be carried easily, meridians are semicircle and parallels are circles – on paper they become straight or curved line
• Need for map projection
• Detailed regions
• Compare 2 natural regions
• Transfer latitude and longitude on flat paper
• Distortions increase with distance from tangential point (throwing light from center)
• Tracing shape, size and directions, etc. from a globe is nearly impossible because the globe is not a developable surface
• Lexodrome or Rhumb Line: It is a straight line drawn on Mercator՚s projection joining any two points having a constant bearing. It is very useful in determining the directions during navigation.
• The Great Circle: It represents the shortest route between two points, which is often used both in air and ocean navigation.
• Homolographic Projection: A projection in which the network of latitudes and longitudes is developed in such a way that every graticule on the map is equal in area to the corresponding graticule on the globe. It is also known as the equal-area projection.
• Orthomorphic Projection: A projection in which the correct shape of a given area of the earth՚s surface is preserved

Elements of Map Projection

• Reduced Earth: A model of the earth is represented by the help of a reduced scale on a flat sheet of paper. This model is called the “reduced earth.” This model should be more or less spheroid having the length of polar diameter lesser than equatorial and on this model, the network of graticule can be transferred.
• Parallels of Latitude: These are the circles running round the globe parallel to the equator and maintaining uniform distance from the poles. Each parallel lies wholly in its plane, which is at right angle to the axis of the earth. They are not of equal length. They range from a point at each pole to the circumference of the globe at the equator. They are demarcated as  to  North and South latitudes.
• Meridians of Longitude: These are semi-circles drawn in north south direction from one pole to the other, and the two opposite meridians make a complete circle, i.e.. circumference of the globe. Each meridian lies wholly in its plane, but all intersect at right angle along the axis of the globe. There is no obvious central meridian but for convenience, an arbitrary choice is made, namely the meridian of Greenwich, which is demarcated as  longitudes. It is used as reference longitudes to draw all other longitudes
• Global Property: In preparing a map projection the following basic properties of the global surface are to be preserved by using one or the other methods:
  • Distance between any given points of a region;
  • Shape of the region;
  • Size or area of the region in accuracy;
  • Direction of any one point of the region bearing to another point.

Classification of Map Projection

• Drawing Surface- Perspective, non-perspective & Mathematical
• Developable (cylindrical, conical and zenithal) & Non-Developable
• Source of light – gnomonic, stereographic and orthographic
• Global properties – area, shape, direction, distance

Classification of Map Projection: Area, Shape & Distance

• Drawing Surface: Perspective projections can be drawn taking the help of a source of light by projecting the image of a network of parallels and meridians of a globe on developable surface. Non – perspective projections are developed without the help of a source of light or casting shadow on surfaces, which can be flattened.
• Mathematical or conventional projections are those, which are derived by mathematical computation and formulae and have little relations with the projected image (Mollweide, sinusoidal/Samson flam steed or homolosine)
• Developable surface: A developable surface is one, which can be flattened, and on which, a network of latitude and longitude can be projected- cylindrical, conical and zenithal projections.
• Zenithal projection is directly obtained on a plane surface when plane touches the globe at a point and the graticule is projected on it. Generally, the plane is so placed on the globe that it touches the globe at one of the poles. These projections are further subdivided into normal, oblique or polar
• If it is tangential to a point between the pole and the equator, it is called the oblique projection; and if it is tangential to the pole, it is called the polar projection
• If the developable surface touches the globe at the equator, it is equatorial or normal projection.
• Non-Developable surface – non-developable surface is one, which cannot be flattened without shrinking, breaking, or creasing. A globe or spherical surface

Source of Light

• Gnomonic projection is obtained by putting the light at the centre of the globe. Stereographic projection is drawn when the source of light is placed at the periphery of the globe at a point diametrically opposite to the point at which the plane surface touches the globe. Orthographic projection is drawn when the source of light is placed at infinity from the globe, opposite to the point at which the plane surface touches the globe
• Global Properties: As mentioned above, the correctness of area, shape, direction, and distances are the four major global properties to be preserved in a map based on global properties; projections are classified into equal area, orthomorphic, azimuthal and equidistant projections.
• (Area) Equal Area Projection is also called homolographic projection. Areas of various parts of the earth are represented correctly in that projection.
• (Shape) Orthomorphic or True-Shape projection is one in which shapes of various areas are portrayed correctly. The shape is generally maintained at the cost of the correctness of area.
• (Direction) Azimuthal or True-Bearing projection is one on which the direction of all points from the centre is correctly represented.
• (Distance) Equi-distant or True Scale projection is that where the distance or scale is correctly maintained. It cannot be maintained throughout but at certain specific locations.

Examples of Cylindrical Projections

• Equal-area cylindrical projection
• Equidistant cylindrical projection
• Mercator projection
• Miller projection
• Plate Carree projection
• Universal transverse Mercator projection

Examples of Conical Projections

• Albers Equal-area projection
• Equidistant projection
• Lambert conformal projection
• Polyconic projection

Examples of Azimuthal Projections

• Equidistant azimuthal projection
• Gnomonic projection
• Lambert equal-area azimuthal projection

Draw a Mercator՚s projection for the world map on the scale of 1: 250,000, 000 at  interval

Construction of Projections

Mercator՚s Projection

A Dutch cartographer Mercator Gerardus Karmer developed this projection in 1569. The projection is based on mathematical formulae. So, it is an orthomorphic projection in which the correct shape is maintained. The distance between parallels increases towards the pole. Like cylindrical projection, the parallels and meridians intersect each other at right angle. It has the characteristics of showing correct directions. A straight line joining any two points on this projection gives a constant bearing, which is called a Laxodrome or Rhumb line.

• Draw a line of 6.28 inches representing the equator as EQ:
• Divide it into 24 equal parts. Determine the length of each division using the following formula: 
• Calculate the distance for latitude with the help of the table given below:-

Latitude Distance

 inch

 inch

 inch

 inches

 inches

Properties

• All parallels and meridians are straight lines and they intersect each other at right angles.
• All parallels have the same length, which is equal to the length of equator.
• All meridians have the same length and equal spacing. However, they are longer than the corresponding meridian on the globe.
• Spacing between parallels increases towards the pole.
• Scale along the equator is correct, as it is equal to the length of the equator on the globe; but other parallels are longer than corresponding parallel on the globe; hence, the scale is not correct along them. For example, the  parallel is 1.154 times longer than the corresponding parallel on the globe.
• Shape of the area is maintained, but at the higher latitudes, distortion takes place.
• The shape of small countries near the equator is truly preserved while it increases towards poles.
• It is an azimuthal projection.
• This is an orthomorphic projection as scale along the meridian is equal to the scale along the parallel.

Limitations

• There is greater exaggeration of scale along the parallels and meridians in high latitudes. As a result, size of the countries near the pole is highly exaggerated. For example, the size of Greenland equals to the size of USA, whereas it is  ^thof USA.
• Poles in this projection cannot be shown as  parallel and meridian touching them are infinite.

Uses

• More suitable for a world map and widely used in preparing atlas maps.
• Very useful for navigation purposes showing sea routes and air routes.
• Drainage pattern, ocean currents, temperature, winds and their directions, distribution of worldwide rainfall and other weather elements are appropriately shown on this map

Construct a cylindrical equal area projection for the world when the R. F. of the map is 1: 300,000, 000 taking latitudinal and longitudinal interval as .

Cylindrical Equal Area Projection

The cylindrical equal area projection, also known as the Lamber՚s projection, has been derived by projecting the surface of the globe with parallel rays on a cylinder touching it at the equator. Both the parallels and meridians are projected as straight lines intersecting one another at right angles. The pole is shown with a parallel equal to the equator; hence, the shape of the area is highly distorted at the higher latitude.

Construction

• Draw a circle of 2.1 cm radius;
• Mark the angles of  and  for both, northern and southern hemispheres;
• Draw a line of 13.2 cm and divide it into 24 equal parts at a distance of  apart. This line represents the equator;
• Draw a line perpendicular to the equator at the point where  is meeting the circumference of the circle;
• Extend all the parallels equal to the length of the equator from the perpendicular line

Properties

• All parallels and meridians are straight lines intersecting each other at right angle.
• Polar parallel is also equal to the equator.
• Scale is true only along the equator.

Limitations

• Distortion increases as we move towards the pole.
• The projection is non-orthomorphic.
• Equality of area is maintained at the cost of distortion in shape.

Uses

• The projection is most suitable for the area lying between N and S latitudes.
• It is suitable to show the distribution of tropical crops like rice, tea, coffee, rubber and sugarcane

Construct a conical projection with one standard parallel for an area bounded by  N to  N latitude and  E to  E longitudes when the scale is 1: 250,000, 000 and latitudinal and longitudinal interval is 

Conical Projection with One Standard Parallel

A conical projection is one, which is drawn by projecting the image of the graticule of a globe on a developable cone, which touches the globe along a parallel of latitude called the standard parallel. As the cone touches the globe located along AB, the position of this parallel on the globe coinciding with that on the cone is taken as the standard parallel. The length of other parallels on either side of this parallel are distorted

Construction

• Draw a circle or a quadrant of 2.56 cm radius marked with angles COE as  interval and BOE and AOD as standard parallel.
• A tangent is extended from B to P and similarly from A to P, so that AP and BP are the two sides of the cone touching the globe and forming Standard Parallel at  N.
• The arc distance CE represents the interval between parallels. A semi-circle is drawn by taking this arc distance.
• X-Y is the perpendicular drawn from OP to OB.
• A separate line N-S is taken on which BP distance is drawn representing standard parallel. The line NS becomes the central meridian.
• Other parallels are drawn by taking arc distance CE on the central meridian.
• The distance XY is marked on the standard parallel at  for drawing other meridians.
• Straight lines are drawn by joining them with the pole

Properties

• All the parallels are arcs of concentric circle and are equally spaced.
• All meridians are straight lines merging at the pole. The meridians intersect the parallels at right angles.
• The scale along all meridians is true, i.e.. distances along the meridians are accurate.
• An arc of a circle represents the pole.
• The scale is true along the standard parallel but exaggerated away from the standard parallel.
• Meridians become closer to each other towards the pole.
• This projection is neither equal area nor orthomorphic.

Limitations

• It is not suitable for a world map due to extreme distortions in the hemisphere opposite the one in which the standard parallel is selected.
• Even within the hemisphere, it is not suitable for representing larger areas as the distortion along the pole and near the equator is larger.

Uses

• This projection is commonly used for showing areas of mid-latitudes with limited latitudinal and larger longitudinal extent.
• A long narrow strip of land running parallel to the standard parallel and having east-west stretch is correctly shown on this projection.
• Direction along standard parallel is used to show railways, roads, narrow river valleys, and international boundaries.
• This projection is suitable for showing the Canadian Pacific Railways, Trans-Siberian Railways, international boundaries between USA and Canada and the Narmada Valley.

NCERT Class 11 Geography Practical Chapter 3: Longitude, Latitude and Time

Earth is Oblate Spheroid or Geiod

• Equatorial radius and the polar radius of the earth is not the same
• Rotation on axis produces bulge at equator
• network of imaginary lines is drawn on a globe or a map to locate various places – geographical grid
• The grid consists of two sets of horizontal and vertical lines, which are called parallels of latitudes and the meridians of longitudes

Latitude or Parallel – Drawing Them

• Horizontal lines parallel to each other and appear as circles
• Angular distance, in degrees, minutes and seconds of a point north or south of the Equator
• Midway between north & south pole is equator
• Divide globe in 2 equal half – great circle
• Rest are smaller – called parallels or latitude
• If parallels of latitude are drawn at an interval of one degree, there will be 89 parallels in the northern and the southern hemispheres each. The total number of parallels thus drawn, including the equator, will be 179.
• If earth was perfect sphere – length of one degree would be 111 km and would be same as longitude.
• But the degree of latitude changes slightly in length from the equator to the poles. While at the equator, it is 110.6 km at the poles, it is 111.7 km.
• Latitude of a place may be determined with the help of the altitude of the sun or the Pole Star.
• Draw Parallels: Draw a circle and divide it into two equal halves by drawing a horizontal line in the center. This represents the equator. Place a protractor on this circle in a way that 0° and 180° line on the protractor coincide with the equator on the paper. Now to draw 20°S, mark two points at an angle of 20° from the equator, east and west in the lower half of the circle. The arms of the angle cut the circle at two points. Join these two points by a line parallel to the equator. It will be 20⁰S.

Longitude or Meridian – Drawing Them

• Run N-S
• Join the poles
• Called meridians
• Angular distance, in degrees, minutes, and seconds, of a point east or west of the Prime (Greenwich) Meridian
• Farthest at equator and converge at poles
• Help in coordinates, location, distance and direction
• Infinite number of these can be drawn – but we draw selected ones
• Latitudes and longitudes are measured in degrees (°) because they represent angular distances. Each degree is further divided into 60 minutes ( ′ ) and each minute into 60 seconds ( ″ ) .
• Unlike the parallels of latitude which are circles, the meridians of longitude are semi-circles that converge at the poles – (if opposite are taken, they complete circle and are valued as 2 meridians)
• The meridians intersect the equator at right angles
• Greenwich is zero-degree meridian passing through London
• The longitude of a place is its angular distance east or west of the Prime Meridian. It is also measured in degrees.
• The rotation of the earth over its axis takes 24 hours to complete one circle or 360° of longitudes. As 180° of longitudes fall both east and west of the Prime Meridian, the sun, thus takes 12 hours՚ time to traverse the eastern and western hemispheres. In other words, the sun traverses 150 of longitudes per hour or one degree of longitude in every four minutes of time
• Distance b/w 2 longitude is maximum at equator 111.3 km and at 45 degrees it is 79 km, converging at poles.
• Determine local time

Solving Problems on Latitude & Longitude

• Determine the local time of Thimpu (Bhutan) located at 90° east longitude when the time at Greenwich (0°) is 12.00 noon.
• Difference between Greenwich and Thimpu = 90° of longitudes
• Total Time difference = 90 x 4 = 360 minutes
• = 360/60 hours
• = 6 hours or Local time of Thimpu is 6 hours more than that at Greenwich, i.e.. 6.00 p. m.
• If the location is 90° west of Greenwich it would be 6 hours behind. We take standard time to maintain uniformity across country
• The Indian Standard Time is calculated from 82°30 ′ E meridian passing through Mirzapur. Therefore, IST is plus 5.30 hours from the GMT
• The world is divided into 24 major time zones

International Date Line

• The 180° line of longitude is approximately where the International Date Line passes
• The time at this longitude is exactly 12 hours from the 0-degree longitude, irrespective of one travels westward or eastward from the Prime Meridian
• Cross eastward <- it is loss a day from Thursday to Friday
• Crossing westward -◊ it is gaining a day Thursday to Wednesday.

Class 11 Sociology Revision Notes for Indian Sociologists of Chapter 5

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EVOLUTION OF SOCIOLOGY AND SOCIAL ANTHROPOLOGY IN INDIA.

• Indian sociology emerged as a separate discipline because the Indian society and social structure was completely different from that experienced by western European societies.
• Indian sociology was formally introduced as a discipline at university level for the first time in 1919 at the University of Bombay.
• In the 1920’s, two other universities, those at Calcutta and Lucknow, also began programmes of teaching and research in sociology and anthropology.
• Today, every major university has a department of sociology, social anthropology or anthropology, and often more than one of these disciplines is represented.
• At the beginning stage, it wasn’t clear as to what should be the subject matter of Indian sociology.
• The need for the subject raised many questions in the Indian context:

1. Western sociology emerged as an attempt to make sense of modernity but the waves of modernity that Indian society was experiencing was entirely different as it was closely entwined with colonial subjugation. Hence, understanding modernity in the Indian context was entirely different then the western societies.
2. Social anthropology in the west developed out of curiosity to know about the primitive cultures but India was an ancient and advanced civilisation already which also had parallel existence of primitive societies within it. Hence, it was felt that different theoretical perspectives are needed to understand the functioning of Indian social structure.

THE SPECIFICITY OF THE DISCIPLINE OF SOCIOLOGY IN INDAIN CONTEXT RAISED MANY QUESTIONS.

1. First of all, if western sociology emerged as an attempt to make sense of modernity, what would its role be in a country like India? India too, was of course experiencing the changes brought about by modernity but with an important difference, it was a colony. The first experience of modernity in India was closely intertwined with the experience of colonial subjugation.
2. Secondly, if social anthropology in the west arose out of the curiosity felt by European society about primitive cultures, what role could it have in India which was an ancient and advanced civilisation, but which also had ‘primitive’ societies within it?
3. Finally, what useful role could sociology have in a sovereign, independent India, a nation about to begin its adventure with planned development and democracy?

The pioneers of Indian sociology not only had to find their own answers to questions like these, they also had to formulate new questions for themselves. It was only through the experience of ‘doing’ sociology in an Indian context that the questions took shape, they were not available readymade.
Pioneers of Indian sociology

• L.K. Ananthakrishna Iyer and Sarat Chandra Roy were true pioneers of Indian sociology in the sense that they began practicing a discipline that didn’t yet exist in India (in early 1900s).
• Moreover, there was no institutions to promote the discipline yet their works were recognised and appreciated amongst well know anthropologists internationally.

L.K. Ananthkrishna Iyer

• He was the first self-taught anthropologist who was the first Indian to carry out an Ethnographic survey of the state of Cochin.
• His work was much appreciated by British anthropologists and administrators.
• He was later appointed as a reader at the University of Calcutta, where he helped set up the first department of post-graduate anthropology.

Sarat Chandra Roy

• He was an accidental anthropologists and pioneer of the discipline.
• He got interested in interpretation of tribal customs and laws as a by- product of his professional need due to practicing law.
• He did intensive fieldwork among various tribal communities.
• He was recognised for his monographs and research articles based on fieldwork and became famous amongst anthropologists in India and Britain.

Early Indian sociologist
G. S. Ghurye

• G. S. Ghurye majorly worked on caste and race in India. His other works included themes like tribes, kinship, family and marriage, culture, civilisation and the historic role of cities, religions and the sociology of conflict and integration.
• His works were influenced by various schools of thoughts such as that of diffusionism, orientalist on Hindu religion and thoughts, nationalism and cultural aspects of Hindu identity.

G. S. Ghurye on caste system
Ghurye emphasised on six main features to help explain the functioning of caste systems:

1. Caste is an institution based on segmental division
2. Caste society is based on hierarchical division
3. The institution of caste necessarily involves restrictions on social interaction
4. Caste also involves differential rights and duties for different castes
5. Caste restricts the choice of occupation
6. Caste involves strict restrictions on marriage

D. P. Mukherjee

• D.P.’s work was mainly emphasised on the crucial role of a social system for society.
• According to him, to study about Indian society means it was necessary to study and know the social traditions of India.
• Understanding the tradition was necessary to understand the social system of a society. T
• his study of traditions not only include its past but also its sensitivity to change and hence, it’s a living tradition.

D.P.’s argument on Indian culture and society as different from the western society:
Indian culture is not individualistic in the western sense because in Indian society individual’s behaviour pattern is rigidly fixed by his socio-cultural group pattern. Indian social system is oriented towards group, sect, caste, etc.

• A R Desai is one of the rare Indian sociologists who was directly involved in politics as a formal member of political parties.
• He has been a life-long Marxist follower who was associated with various kinds of non-mainstream Marxist political groups.
• His best work was the social background of Indian nationalism. Various other themes that Desai worked on are Peasant movements, Rural sociology, Modernisation and urban issues, Political sociology, Forms of the state and human rights, etc.
• Desai offered a Marxist analysis of Indian nationalism where he gave prominence to economic processes and divisions of the specific conditions of British colonialism.
• According to Desai, India’s nationalism is the result of the material conditions created by the British colonialism.
• The Britishers developed new economic relations by introducing industrialization and modernization.
• Desai thinks that when traditions are linked with economic relations, the change in the latter would eventually change the traditions.
• It is in this context that he thinks that caste will disintegrate with the creation of new social and material conditions, such as industries, economic growth, education, etc.

Desai on welfare state

• Modern capitalist state was one of the most significant themes of interest to A R Desai.
• Using a Marxist approach, he provided a detailed critique of the notion of welfare state and pointed out many of its shortcomings.

Features that describes a welfare state.

• A welfare state is a positive state. This means that, unlike the ‘laissez faire’ of classical liberal political theory, the welfare state does not seek to do only the minimum necessary to maintain law and order.
• The welfare state is a democratic state. Democracy was considered an essential condition for the emergence of the welfare state.
• A welfare state follows a ‘mixed economy’ means an economy where both private capitalist enterprises and state or publicly owned enterprises co-exist. A welfare state does not seek to eliminate the capitalist market, nor does it prevent public investment in industry and other fields.

Test criteria suggested by Desai against which the performance of the welfare state can be measured

• Does the welfare state ensure freedom from poverty, social discrimination and provide security for all citizens?
• Does the welfare state remove inequalities of income?
• Does the welfare state transform the economy to use the capitalist profit to the benefits ofmeeting the real needs of the community?
• Does the welfare state ensure stable development free from economic booms and depressions?
• Does it provide employment for all?

The notion of the welfare state is a myth

• Using the test criteria identified for welfare state, Desai examines the performance of those states that are most often described as welfare states, such as Britain, the USA and much of Europe, and finds their claims to be greatly exaggerated.
• Thus, most modern capitalist states, even in the most developed countries, fail to provide minimum levels of economic and social security to all their citizens.
• They are unable to reduce economic inequality and often seem to encourage it.
• The so-called welfare states have also been unsuccessful at enabling stable development free from market fluctuations.
• The presence of excess economic capacity and high levels of unemployment are yet another failure.
• Based on these arguments, Desai concludes that the notion of the welfare state is something of a myth.

M N Srinivas

• M N Srinivas is popularly known as the sociologist of the post-independence era. Major influence on his work was the outcome of his association with the British social anthropology discipline.
• He successfully established Indian sociology on the world map and was instrumental in making village studies the dominant field in Indian sociology.
• Other major themes he worked on are caste, modernisation and process of social change.
• Srinivas’s village studies were based on two broad types of writings:

1. i) Ethnographic accounts of fieldwork done in villages
2. ii) Historical and conceptual discussions about Indian villages as a unit of social analysis

• Srinivas believed that the village was a relevant social entity.
• Srinivas also criticised the British administrator anthropologists who had put forward a picture of the Indian village as unchanging, self-sufficient, “little republics”.
• Using historical and sociological evidence, Srinivas showed that the village had, in fact, experienced considerable change.
• He emphasised the usefulness of the village as a concept. However, some sociologists like Louis Dumont argued against village studies as they thought that social institutions like castes were more important than something like a village due to the reason that villages may live or die, and people may move from one village to another, but their social institutions, like caste or religion, follow them and go with them wherever they go.
• Dumont believed that it would be misleading to give much importance to the village as a category.

Advantages of village studies as a site of research

• It provided an opportunity to illustrate the importance of ethnographic research methods.
• It offered eye-witness accounts of the rapid social change that was taking place in the Indian countryside as the newly independent nation began a programme of planned development.
• These vivid descriptions of village India were greatly appreciated at the time as urban Indians as well as policy makers were able to form impressions of what was going on in the heartland of India.
• Village studies thus provided a new role for a discipline like sociology in the context of an independent nation.
• The study of village is also relevant to the study of a modernised India.

Class 11 Sociology Revision Notes for Introducing Western Sociologists of Chapter 4

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• Three major social processes developed the intellectual ideas and materialistic aspects that went into the making of sociology as a discipline. These social processes were:
  • The age of reason or enlightenment
  • The French revolution
  • The scientific or industrial revolution
• The modern era in Europe and the conditions of modernity that we take for granted today were brought about by these three major processes.
• The ideas of the classical thinkers like Marx, Weber and Durkheim about society were influenced by social conditions of the three processes that helped sociology to emerge.
• Emergence of radically new ways of thinking about the world made it felt necessary to displace nature, religion and the divine acts of gods from the central position they had in earlier ways of understanding the world.
• It helped to develop attitudes of mind that is referred to as secular, scientific and humanistic.

The Age of Enlightenment

• The age of enlightenment is important in the development of sociology because it helped in establishing human being, the subject matter of sociology at the centre of the universe.
• It established the ability to think rationally and critically and that transformed humans into both the producer and the user of all knowledge.
• This was the era when society was considered as the handiwork of humans and thus amenable to rational analysis.

The French Revolution
– The French Revolution introduced political sovereignty at the level of individuals as well as nation states.
– Questioning the legitimacy of privileges inherited by birth was made possible due to declaration of human rights.
– Emancipation of individuals from the oppressive rule of religious and feudal institutions became possible due to political sovereignity.
– Every citizen was given equal rights before the law and other institutions of the state.
– Separated the private realm from the public sphere and state had to respect individual autonomy without intruding it.
– Ideas like liberty, equality and fraternity became the watchwords of the modern states.
– The conditions of modernity brought by the French Revolution thus laid the ground for sociology to study the new social phenomena.
The Industrial Revolution
– The industrial revolution laid down numerous conditions that were responsible for the rise of sociology as a discipline.
– Sociological thought was concerned with the scientific analysis of developments in industrial society, the foundations of which was laid down by the industrial revolution.

• Durkheim was the first professor of sociology and hence, known as the founder of sociology as a formal discipline.
• Society for him was a social fact that existed as a moral community over and above the individual.
• Social ties that bound people in groups are crucial to the existence of society as these exert pressure on individuals to conform to norms and expectations of groups.
• Durkheim’s vision of sociology was characterised by two defining features:
  • The subject matter of sociology that is social facts
  • Sociology can be defined as an empirical discipline as the social facts can be empirically
• Social facts are the level of complex collective life where social phenomena/social fact can emerge like in the social institutions of religion or the family.
• Social facts are social values like friendship or patriotism that exist in the larger society.
• Individuals functions according to these social facts.
• Sociology can be termed as an empirical discipline as the subject matter of sociology that is social facts is observable and can be empirically tested and verified.
• As individuals follow social facts, their behaviour become regulated and patterned. The social facts are external to individuals however these constrain human behaviour. Hence, social facts are indirectly observable through behavioural patterns of individuals who are part of society.
• According to Durkheim, modern society can be characterised by the following features:
  • Individuals with similar goals come together voluntarily and form associations or groups.
  • Individuals might belong to various such groups and thus have many different identities.

MAJOR WORKS OF MAX WEBER

• Weber developed an interpretative sociology of social action and of power and domination.
• According to Weber, the process of rationalisation in modern society has relationship of the various religions of the world.
• Weber suggested that human actions carry subjective meaning and to study these, sociologist need to constantly practice ‘empathetic understanding’ to be objective.
• Weber use the ideal type to illustrate the three types of authority that he defined as traditional, charismatic and rational-legal.
• While the source of traditional authority was custom and precedence, charismatic authority derived from divine sources or the ‘gift of grace’, and rational-legal authority was based on legal demarcation of authority that is inherent in the bureaucracy of modern times.

Bureaucracy
Bureaucracy is a mode of organisation which was premised on the separation of the public from the private (domestic) world. This means the behaviour in the public domain was regulated by explicit rules and regulations.
As a public institution, bureaucracy restricted the power of the officials in regard to their responsibilities and did not provide absolute power to them.
Characteristic features of bureaucratic authority

1. Functioning of Officials
2. Hierarchical Ordering of Positions
3. Reliance on Written Document
4. Office Management
5. Conduct in Office

Functioning of Officials

• Within the bureaucracy officials have fixed areas of ‘official jurisdiction’ governed by rules, laws and administrative regulations.
• The regular activities of the bureaucratic organisation are distributed in a fixed way as official duties.
• As duties are to be fulfilled on a regular basis, only those who have the requisite qualifications to perform them are employed.
• Official positions in a bureaucracy are independent of the incumbent as they continue beyond the tenure of any occupant.

Hierarchical Ordering of Positions

• Authority and office are placed on a graded hierarchy where the higher officials supervise the lower ones.
• Hierarchical ordering of position allows scope of appeal to a higher official in case of dissatisfaction with the decisions of lower officials.

Reliance on Written Document  
– The management of a bureaucratic organisation is carried out on the basis of written documents (the files) which are preserved as records.
Office Management
– As office management is a specialised and modern activity it requires trained and skilled personnel to conduct operations.
Conduct in Office

• As official activity demands the full time attention of officials irrespective of her/his delimited hours in office, hence an official’s conduct in office is governed by exhaustive rules and regulations.
• These rules and regulations have legal recognition, officials can be held accountable

Class 11 Sociology Revision Notes for Environment and Society of Chapter 3

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• Social relationships with the environment have changed over time and they vary from place to place.
• There are a few environmental problems that demand attention.
• All societies have an ecological basis. The term ‘ecology’ denotes the web of physical and biological systems and processes of which humans are one element.
• The ecology of a place is also affected by the interaction between its geography and hydrology.
• Cultural interventions due to human actions can also modify the ecology of a place. For instance, the use potato today in India though seems to be natural was actually a modification in environment by cultural interventions due to human actions.
• Ecology indeed has been modified by human actions over a period of time. For instance, what appears to be a natural feature of the environment such as aridity or flood proneness is often produced by human intervention. Deforestation in the upper catchment of a river may make the river more flood-prone.
• It is often difficult to separate and distinguish between the natural and human factors that brings ecological change. For instance, an agricultural farm is a human transformation of nature. The city environment is also a human artifact.
• When there is interaction between biophysical ecology and human interventions, it leads to emergence of social environment. This interaction is a two-way process, where nature shapes society and society shapes nature.
• The interaction between environment and society is shaped by social organisation. It is basically the relationship that different social groups have with property. This property relation determines how and by whom natural resources can be used.
• Social organisation influences how different social groups relate to their environment.
• The relationship between environment and society also reflect different social values, norms and knowledge systems. For instance, values underlying capitalism have supported commodification of nature, turning it into objects that can be bought and sold for profit.

Relationship between environment and society

• The nature versus nurture debate is a long standing controversy about the effects of biology and social systems on individuals and their behaviour.
• The nature side argues that people are shaped primarily by genetics and biology. Nurture side alternatively argues that our participation is social life is the most important determinant of who we are and how we behave.
• Hence, environment shapes society and it in turn shapes individuals’ behaviour.

Risk society

• According to Anthony Giddens, a risk society is “a society increasingly preoccupied with a future that generates the notion of risk.
• For instance, incidents like nuclear disaster of Chernobyl, industrial accidents like Bhopal and Mad cow disease in Europe shows the dangers inherent in industrial environments and that the human population is living in a risk society.
• We consider ourselves as living in risk societies because human relations with the environment have become increasingly complex in modern society due to spread of industrialisation.
• The complex industrial technologies and modes of organisation require sophisticated management systems which are often fragile and vulnerable to error. We do not fully grasp the technologies and products we use. Hence, are unaware of the risk involved.

Major Environment Problems and Risks
Resource Depletion

• Resource depletion refers to exhaustion of non-renewable natural resources.
• Using up of non- renewable resources is one of the most serious environmental problems.
• Depletion of fossil fuels like petroleum is always in news. The depletion and destruction of water and land is occurring at a rapid pace as aquifers accumulated with water are getting emptied to meet growing demands of intensive agriculture, industry and urban centres.
• Other major rapid resource depletion includes biodiversity habitats like forests, grasslands and wetlands largely due to expansion of agriculture.
• The risks or adverse consequences due to resource depletion are many fronts. For example, water crisis, loss of fertile soil, flood risk, etc.

Pollution

• Pollution is one of the major environmental problems.
• Different types of environmental pollutions are air pollution, water pollution and noise pollution.
• Air pollution is considered to be a major environmental problem in urban and rural areas.
• Sources of air pollution include emissions from industries and vehicles, burning of woods and coal for domestic use.
• Indoor air pollution from cooking fire is also a major source of risk especially in rural homes due to poor ventilation.
• Water pollution is a serious problem affecting surface as well as groundwater.
• Sources of water pollution include domestic sewage, factory waste, runoffs from agricultural farms using synthetic fertilisers and pesticides.
• Noise pollution is mostly caused in city. Sources of noise pollution include amplified loud speakers, political campaigns, vehicle horns, traffic, construction works, etc.
• Various risks or consequences due to pollution
• Air pollution can cause respiratory problems resulting in serious illness and death.
• Indoor pollution from fire used for cooking inside poorly ventilated homes can put village women at serious risks.
• WHO estimates that almost 600,000 people died due to indoor pollution in Indian in 1998 and almost 500,000 of them were in rural areas.
• Water pollution can cause water borne diseases, contaminated drinking water.
• Noise pollution can cause hearing impairments due to sound energy produced.

Global Warming

• Global warming is a major environmental problem caused by release of gases like carbon dioxide, methane, etc.
• There are multiple risks and consequences faced by the society due to global warming. Significant rise in global temperatures can result in climate change projected to melt polar ice-fields and rise in sea level.
• Climate changes can lead to submerging of low-lying coastal areas and also affect the global ecological balance. It will result in greater fluctuations and uncertainty in climates across the globe.
• Global warming is likely to result in greater fluctuations and uncertainty in climates across the world.

Genetically modified organism

• Genetically modified organisms are the outcome of a new technique of gene-splicing allowing scientists to import genes from one species to another and introducing new characteristics.
• Genetic modifications are done to reduce growing time, increasing size and store life of a product. However, there are numerous risk and consequences due to this.
• Human community knows very little about the long term effects of genetic modifications on those who consume these foods and on the ecosystem.
• Moreover, agricultural companies can use this technique to create sterile seeds preventing farmers from reusing them and forcing them to be dependent on such companies.

Natural and man-made environmental disasters

• Human society has faced lots of risk and consequences due to natural and man-made environmental disasters.
• The Bhopal disaster of 1984, when a toxic gas leak from the Union Carbide factory, it killed about 4000 people, and the tsunami of 2004 are the most recent examples of man-made and natural environmental disasters.

Environmental problems are also social problems

• Environmental problems are actually social problems because environmental problems affect different social groups differently due to social inequality.
• Social status and power determine the extent to which people can protect themselves from environmental crises or overcome them.
• Overcoming environmental problems by certain groups can sometimes actually worsen environmental disparities.
• Certain environmental problems might be of universal concern and not related to specific social groups but how these problems are pursued may not be universally beneficial to all due to how public priorities are set.
• Securing public interests from environmental crises can actually serve the interests of particular politically and economically powerful groups and hurt the interests of poor and politically weak. Thus, environment as a public interest is a hugely debated topic.
• Varied interests and ideologies related to the environment by different groups in societies generate environmental conflicts.
• To address such environmental problems, it is required to change the environment-society relations that exists in society. To change environment society relations, it needs efforts to change relations between different social groups.
• Changed social relations between different social groups will give rise to different knowledge systems and modes of managing the environment.

Sociology Class 11 Notes Chapter 2 Social Change and Social Order in Rural and Urban Society

• Change is the most permanent feature of any society. Social change can be defined as transformation in the methods of thinking and working of people. It is basically changes in social structures and social relationships of a society.
• Social change occurs due to physical, social, demographic, cultural and technological factors.
• Population growth influences adversely on the usage of natural resources which also causes social change.
• Evolution, progress and revolution are various forms of social change.
• Sudden or accidental changes are called revolution whereas slow and gradual social changes are called revolutions.
• Social change is a broader concept. It includes all the areas of society like political, cultural, economic and physical etc. By and large there are five broad sources of social change i.e. environmental, technological, economic, political and cultural change.
• Social change can be seen in terms of structural changes. Structural change refers to transformation in the structure of society to its institutions or the rules by which these institutions run e.g. Paper money as currency marked a major change in the organisation of financial markets and transactions.
• Changes in values and belief can also facilitate change.
• Physical environment and ecology also play a significant role in the structure of society e.g. poor economic conditions are inevitable in the geographical regions where natural calamities are common.
• Technology also alters nature and relationships. It allows us to adopt to the problems posed by nature. For example, Japan being mostly hilly and cold country developed expertise in electrical and electronic gadgets.
• Industrial revolution has caused massive social changes in almost all the societies of the world.
• Use of gun powder, paper, mode of transport, railways and aviation’s have brought tremendous social changes.
• The social changes due to technological factors are very fast and complex.
• Social changes occur differently in rural and urban societies.
• Rural societies are mostly agriculture based and this lacks technology and specialization. People are more comfortable with traditional knowledge and members of their group instead of experts.
• Joint family system, caste system, superstitions, homogeneity and illiteracy are very common in rural societies. In such societies social change is particularly very slow.
• Urban societies are mostly industrialized. There is differentiation and stratification not only on the basis of caste but also class.
• Heterogeneity in occupation is common. There are a variety of people and culture in a high density area.
• The association and relationship are secondary and time based.
• People of different castes, religions and regions live together with more tolerance.
• Urban societies are slightly individualistic and characteristic segregation of groups and functions significantly.
• Cities are basically commercial hubs.
• In such urban societies social changes are drastic and quick.
• As social change is inevitable, similarly all societies need to have a network of social control.
• Social control means the active maintenance and reproduction of a particular pattern of social relations and of values and norms.
• All societies encourage members spontaneously. They abide by a set of rules and norms or people are compelled in various ways to obey such norms.
• For control, society needs authority. Authority is a person who has inherent power to give reward or punishment to maintain social network. According to Weber, authority is a legitimate power. Bureaucracy, police, judiciary etc. exercise their power. The authority is provided to them by the system.
• Domination and law are another aspects of social control.
• Domination is a psychological phenomena. Dominance exists as a feeling in the personality of the individual. It is a personal trait which ir.ay also be related to a specific situation e.g. a father has a dominant role in Indian family system.
• Law refers to an explicitly codified norm or rule which is usually in written form.
• In social term, legitimacy refers to the degree of acceptance that is involved in power relations.
• Contestation is a broad form of insistent disagreement. Competition and conflict are more specific than this. Counter cultures among faith is example of this. These are refusal to conform to prevalent social norms.
• Contestations are manifestation of protest against laws or lawful authorities.
• A crime is an act that violates an existing law. Basically crime is the breaking of the law.
• Crime has many features like any behavior prohibited by law, criminal intent. It is directly linked with punishment, positively correlated to behavior and causing harm etc.
• There are various factors of crime like biological factors, economic factors, geographical factors, socio-cultural and psychological factors.

Important terms:

• Authority: It refers to a person or institution which has inherent power to give reward or punishment. It may be traditional authority, legal authority or charismatic authority. According to Weber, it is legitimate power.
• Social change: Changes which occur in the social organisation or social structure and function.
• Internal social change: Changes in norms and values.
• External social change: Changes in forms of family, marriage, caste, class, kinship, marriage etc.
• Change: Difference in the form of any condition or existence from its previous form is called change.
• Cultural lag: Any imbalance that occurs in the speed of change between two types of culture.
• Law: Body of rules which are recognized, interpreted and applied to particular situations by the courts of the state.
• Contestation: The broad forms of insistent disagreement. A situation when people tend to protest against to conform to existing social norms.
• Conformity: A type of social influence. It is behavior according to pre-existing group norms.
• Obedience: A type of social influence. It is behavior according to the orders or command of any authority.
• Compliance: A type of social influence. It is behavior according to request made by some one, may be an authority.
• Social sanctions: Related to reward and punishments that are used to bring about social control.
• Crime: Any act of the individual that violates the existing law is considered as crime.
• Diffusion: Transmission of some traits of a particular culture to another culture, which causes change is known as diffusion.
• Social evolution: A kind of social change which manifests gradual and slow process of change in institutions.
• Revolution: Sudden or accidental change in the structure of society is called revolution.
• Charismatic authority: A leader having great influence on others due to his personality is known as charismatic authority.
• Rural society: A simple community based on agriculture.
• Urban society: A large organisation of people living in limited area with high population, density and high degree of intercommunication.
• Village: A unit of the rural community, where rural life upholds itself and does perform its functions.