CBSE Class 11

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 14 Movements of Ocean Water Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Movements of Ocean Water NCERT Solutions for Class 11 Geography Chapter 14

Movements of Ocean Water Questions and Answers Class 11 Geography Chapter 14

Question 1.
Multiple Choice Questions :
(i) Upward and downward movement of ocean water is known n as the:
(a) tide
(b) current
(c) wave
(d) none of the above
Answer:
(a) tide

(ii) Spring tides are caused :
(a) As a result of the moon and the sun pulling the earth gravitionally in the same direction
(b) As a result of the moon and sun pulling the earth gravitationally in the opposite direction
(c) Indention in the coastline
(d) None of the above
Answer:
(a) As a result of the moon and the sun pulling the earth gravitationally in the same direction.

(iii) The distance between the earth and the moon is minimum when the moon is in
(a) Aphelion
(b) Perigee
(b) Perihelion
(d) Apogee
Answer:
(b) Perigee.

(iv) The earth reaches its perihelion in :
(a) October
(b) September
(c) July
(d) January
Answer:
(d) January.

Question 2.
Answer the following questions in about 30 words each :
(i) What are waves?
Answer:
Waves are the oscillatory movement of water, where particles move up and down in a vertical plane.

(ii) Where do waves in the ocean get their energy from?
Answer:
Waves are actually not the energy water as such. Wind provides energy to the waves. Wind causes waves to travel in the ocean and energy is released on the shorelines. The motion of the surface water seldom affects the stagnant deep bottom waters of the oceAnswer:As the wave approaches the beach, it slows down.

(iii) What are tides?
Answer:
Tides are the periodic rise and tall in the level of water in oceans and seas caused by the differential attraction of the moon and the sun.

(iv) How are tides caused?
Answer:
Tides are produced as gravitational interaction of the earth, moon and the sun. Twice a day, the sea level rises and falls. The rise of sea level is called the flood tide and the fall is called the ebb tide.

(v) How are tides related to navigation?
Answer:
Since the tides are caused by the earth-moon-sun positions, which are known accurately, the tides can be predicted well in advance This helps the navigators and fishermen plan their activities. Tidal flows are of profound importance in navigation. Tidal heights near the rivers prevent ships and boats from entering into the harbour.

Question 3.
Answer the following questions in about 150 words each :
(i) How do currents affect the temperature? How do they affect the temperature of coastal areas in the N.W. Europe?
Answer:
The ocean current affects the temperature. The west coasts of the continents in tropical and sub-tropical latitudes (except close to the equator) are bordered by cool waters.

Their average temperatures are relatively low with narrow diurnal and annual ranges. There is fog, but generally the areas are arid. West coasts of the continents in middle and higher latitudes are bordered by warm waters which cause a distinct marine climate.

They are characterised by cool summers and relatively mild winters with a narrow annual range of temperatures. Warm currents flow parallel to east coasts of the continents in tropical and sub-tropical latitudes. This results in warm and rainy climates. These areas lie in the western margins of the sub-tropical anticyclones.

Effect of oceanic currents on the temperature in Europe :
The Antilles current is the western extension of the North Equatorial current. It flows along the northern side of the Greater Antilles. The Gulf Stream current begins from the Florida Strait and flows northward and eastward along the sea coast of United States. Here, heavy fogs form

along the boundary where the warm Gulf Stream meets the cold Labrador current. The mixing helps the planktons, the micro-nutrients of the fish, to flourish.

The warm Gulf Stream current is responsible for the mild climate that prevails throughout the north-western Europe. Even in winter, Norwegian ports along the Atlantic are ice-free most of the time. In contrast, a cold ocean current flowing equatorward along the west coast of the continents brings relatively cool summer and cold winter.

(ii) What are the causes of currents?
Answer:
Causes of currents :
(a) Prevailing winds – Ocean currents are primarily wind determined. Currents follow the main direction of the planetary winds.

(b) Difference in temperature – Wave in winter is higher and rises, but the cold water is denser and sinks. This creates the difference in sea temperature.

(c) Rotation of earth – Rotation of the earth changes the direction of currents to assure circular direction. The ocean currents in the northern hemisphere are deflated to the right side and in the southern hemisphere to the left.

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 13 Water (Oceans) Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Water (Oceans) NCERT Solutions for Class 11 Geography Chapter 13

Water (Oceans) Questions and Answers Class 11 Geography Chapter 13

Question 1.
Multiple Choice Questions :

(i) Multiple Choice Questions:
(1) Identify the element which is not a part of the hydro logical cycle.
(a) Evaporation
(b) Hydration
(c) Precipitation
(d) Condensation
Answer:
(b) Hydration.

(ii) The average depth of continental slope varies between
(a) 2-20 m.
(b) 200-2,000 m.
(c) 20-200 m.
(d) 2,000-20,000 m.
Answer:
(b) 200-2,000 m.

(iii) Which one of the following is not a minor relief feature in the oceans?
(a) Seamount
(b) Oceanic Deep
(c) Atoll
(d) Guyot
Answer:
(c) Atoll.

(iv) Salinity is expressed as the amount of salt in grams dissolved jn sea water :
(a) 10 gm.
(b) 1,000 gm.
(c) 100 gm.
(d) 10,000 gm.
Answer:
(b) 1,000 gm.

(v) Which one of the following is the smallest ocean?
(a) Indian Ocean
(b) Arctic Ocean
(c) Atlantic Ocean
(d) Pacific Ocean
Answer:
(a) Indian Ocean.

Question 2.
Answer the following questions in about 30 words each :

(i) Why do we call the earth a Blue planet?
Answer:
Because of abundance of water on its surface, the earth is often called a Blue planet.

(ii) What is a continental margin?
Answer:
Continental margins are the relief features of the earth. They consist of two major submarine features, the continental shelf and continental slope.

The continental shelf fringes the continents in width from a few km. to 300 km. The slope abruptly is replaced by the continental rise.

(iii) List out the deepest trenches of various oceans.

(iv) What is a thermocline?
Answer:
The temperature-depth profile for ocean water shows how temperature decreases with increasing depth. The profile shows a boundary region between surface waters of the ocean and deeper layers. This boundary region, where there is a rapid decrease of temperature, is called the thermocline.

(v) When you move into the ocean, what thermal layers would you encounter? Why the temperature varies with depth?
Answer:
As we move into the ocean, we would encounter three layers from surface to the bottom. The temperature varies with depth. Latitude, unequal distribution of land and water affects the distribution of temperature. Temperature decreases with depth because sun’s rays become more and more slanting and thus the amount of insolation decreases polewards.

(vi) What is salinity of sea water?
Answer:
Salinity is the total amount of dissolved salts in sea water. It is calculated as the amount of salt dissolved in 1000 gms of sea water.

Question 3.
Answer the following questions in about 150 words each :
(i) How are various elements of hydrological cycle interrelated?
Answer:
Hydrological cycle is one of the most fundamental cycles that maintains life on earth. The hydrological cycle depends basically on the interrelationship between the circulation of ocean water and that of the atmosphefe. The interrelationship between these elements is a very complex process.

Water withdrawn from the oceans into the atmosphere by process of evaporation depends on air and sea temperatures and on wind strength and humidity. Another relationship between ocean and hydrological cycle is raising up minute particles of salt and other minerals from the sea.

The salt returns to the oceans through rainfall, rivers and other phases of the hydrological cycle. Hydrological cycle is concerned with water in all its forms, i.e., solid (ice), liquid (water) and gas (water vapour). The interaction between ocean and atmosphere involves all the three states of water – solid, liquid and gaseous.

(ii) Examine the factors that influence the temperature distribution of the oceans.
Answer:
The major source of temperature of the oceanic water is the sun. The various factors which affect the distribution of temperature of the ocean water include ‘attitude, unequal distribution of land and water, prevailing wind, ocean currents, and minor factors like submarine ridges, local weather condition and shape and size of the sea. On an average, the temperature of the surface water of the oceans is 26.7°C. It decreases gradually from equator to the poles.

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 12 World Climate and Climate Change Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

World Climate and Climate Change NCERT Solutions for Class 11 Geography Chapter 12

World Climate and Climate Change Questions and Answers Class 11 Geography Chapter 12

Question 1.
Multiple choice questions :
(i) Which one of the following is suitable for Koeppen’s “A” type of climate?
(a) High rainfall in all the months
(b) Mean monthly temperature of the coldest month more than freezing point
(c) Mean monthly temperature of all the months more than 18°C
(d) Average temperature for all the months below 10°C
Answer:
(b) Mean monthly temperature of the coldest month more than freezing point.

(ii) Koeppen’s system of classification of climates can be termed as :
(a) Applied
(b) Systematic
(c) Genetic
(d) Empirical
Answer:
(d) Empirical.

(iii) Most of the Indian Peninsula will be grouped according to Koeppen’s system under :
(a) “Af”
(b) “BSH”
(c) “Cfb”
(d) “Am”
Answer:
(d) “Am”

(iv) Which one of the following years is supposed to have recorded the warmest temperature the world over?
(a) 1990
(b) 1998
(c) 1885
(d) 1950
Answer:
(a) 1990.

(v) Which one of the following groups of four climates represents humid conditions?
(a)A-B-C-E
(b) A-C-D-E
(c) B-C-D-E
(d) A – C – D -F
Answer:
(b) A-C-D-E.

Question 2.
Answer the following questions in about 30 words each
(i) Which two climatic variables are used by Koeppen for classification of climate?
Answer:
Koeppen recognised five major climatic groups, four of them are based on temperature and one on precipitation. The capital letters A, C, D and E delineate humid climates and B dry climates.

(ii) How is the “genetic” system of classification different from the “empirical” one?
Answer:
Empirical classification is based on observed data, particularly on temperature and precipitation. Genetic classification attempts to organise climates according to their causes.

(iii) Which types of climates have very’ low range of temperature?
Answer:
ITCZ makes the climate hot and humid. Annual range of temperature is very low and annual rainfall is high. The tropical group is divided into three types, namely:

• Af-Tropical wet climate
• Am – Tropical monsoon climate
• Aw – Tropical wet and dry climate.

(iv) What type of climatic conditions would prevail if the sun spots increase?
Answer:
According to some meteorologists, when the number of sunspots increase, cooler and wetter weather and greater storminess occur.

Question 3.
Answer the following questions in about 150 words each :
(i) Make a comparison of the climatic conditions between the “A” and “B” types of climates.
Answer:
The tropical group “A” is divided into three types, namely :

• Af – Tropical wet climate.
• Am – Tropical monsoon climate
• Aw – Tropical wet and dry climate.

Tropical wet climate (Af) is found near the equator such as the Amazon basin in South America, western equatorial Africa and the islands of East Indies. The maximum temperature on any day is around 30°C while the minimum temperature is around 20°C.

Tropical monsoon climate (Am) is found over the Indian sub-continent, north eastern part of South America and northern australia. Heavy rainfall occurs mostly in summer. Winter is dry. Tropical wet and dry climate (Aw) occurs north and south of Af type climate regions. Extensive Aw climate is found to the north and the south of the Amazon forest in Brazil and adjoining parts of Bolivia and Paraguay in South America, Sudan and south of Central Africa.

Dry climates “B” are divided into steppe or semi-arid climate (BS) and desert climate (BW). They are sub-divided as sub-tropical steppe (BSh) and sub-tropical desert (BWh) at latitudes from 15°-35° and mid-latitude steppe (BSk) and mid-latitude desert (BWk) at latitudes between 35°-60°.

Sub-tropical steppe (BSh) and sub-tropical desert (BWh) have common precipitation and temperature characteristics. Located in the transition zone between humid and dry climates, subtropical steppe receives slightly more rainfall than the desert.

(ii) What type of vegetation would you find in the “C” and “A” type(s) of climate?
Answer:
Warm temperate (mid-latitude) climates “C” extend from 30’-50″ of latitude mainly on the eastern and western margins of continents. These climates generally have warm summers with mild ‘winters. They are grouped into four types :

• Humid sub-tropical, i.e., dry in winter and hot in summer (CWa);
• Mediterranean (Cs);
• Humid sub-tropical, i.e., no dry season and mild winter (CFa);
• Marine west coast climate (Cfb).

Tropical Humid climates “A”—evergreen forests with dense canopy cover and large bio-diversity are found in this climate. Deciduous forest and tree-shredded grasslands occur in this climate.

(iii) What do you understand by the term “Greenhouse Gases”? Make a list of greenhouse gases.
Answer:
The term ‘greenhouse’ is derived from the analogy to a greenhouse used in cold areas for preserving heat. A greenhouse is made up of glass. The glass which is transparent to incoming short wave solar radiation. The glass, therefore, allows in more radiation and prevents the long wave radiation going outside the glasshouse, causing the temperature inside the glasshouse structure warmer than outside.

When you enter a car or a bus during summers, where windows are closed, you feel more heat inside than outside. Likewise during winter, the vehicles with closed doors and windows remain warmer than the temperature outside. This is another example of the greenhouse effect.

List of GHGs: The gases that absorb long wave radiation are called greenhouse gases such as carbondioxide (CO,), Chlorofluorocarbons (CFCs), methane (CH₄), nitrous oxide (N,O) and ozone (O,), nitric oxide (NO) and carbon monoxide (CO).

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 11 Water in the Atmosphere Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Water in the Atmosphere NCERT Solutions for Class 11 Geography Chapter 11

Water in the Atmosphere Questions and Answers Class 11 Geography Chapter 11

Question 1.
Multiple Choice Questions :
(i) Which one of the following is the most important constituent of the atmosphere for human beings?
(a) Water vapour
(b) Nitrogen
(c) Dust particles
(d) Oxygen
Answer:
(a) Water vapour.

(ii) Which one of the following process is responsible for transforming liquid into vapour?
(a) Condensation
(b) Transpiration
(c) Evaporation
(d) Precipitation
Answer:
(c) Evaporation.

(iii) The air that contains moisture to its full capacity :
(a) Relative humidity
(b) Specific humidity
(c) Absolute humidity
(d) Saturated air
Answer:
(d) Saturated air.

(iv) Which one of the following is the highest cloud in the sky?
(a) Cirrus
(b) Stratus
(c) Nimbus
(d) Cumulus
Answer:
(a) Cirrus.

Question 2.
Answer the following questions in about 30 words each :

(i) Name the three types of precipitation.
Answer:
Precipitation occurs in three ways :

• Convectional precipitation,
• Orographic precipitation,
• Cyclonic precipitation.

(ii) Explain relative humidity.
Answer:
Relative humidity : The percentage of moisture present in the atmosphere as compared to its full capacity is known as relative humidity.

The amount of water vapour in the air compared with the amount that would be present if the air was saturated at that temperature. It is expressed in percentage determined by dividing the absolute humidity by water holding capacity of air.

If the air is saturated, its relative humidity is 100%; if only half saturated, the relative humidity is 50%. Since the capacity of air for absorbing and retaining moisture varies with temperature, the relative humidity of air mass can be altered by merely lowering its temperature without changing the actual amount of moisture present in it.

(ii) Why does the amount of water vapour decrease rapidly with altitude?
Answer:
Water vapour in the atmosphere is the result of evaporation of water from the earth’s surface, a continual process dependent on air. Since the air becomes thinner with altitude, so also does the water vapour.

(iv) How are clouds formed? Classify them.
Answer:
Clouds are formed by the condensation of water vapour around nuclei of minute dust particles in the air. In most cases, clouds consist of tiny droplets of water, but they may also consist of ice particles if temperature is below freezing point. Most clouds are formed by the rising warm and moist air. The ascending air expands and cools until the dew point is reached and some of the moisture condenses into clouds.
The clouds are of three types :

• High clouds : Cirrus, cirrostratus, cirrocumulus.
• Middle clouds : Altostratus, altocumulus.
• Low clouds: Stratocumulus, stratus, nimbostratus, cumulus and cumulonimbus.

Question 3.
Answer the following questions in about 150 words each :
(i) Discuss the salient features of the world distribution of precipitation.
Answer:
Different places on the earth’s surface receive different amount of rainfall. As we proceed from the equator towards the poles, rainfall goes on decreasing. The coastal areas of the world receive greater amount of rainfall than the interior regions of the continents.

On the basis of the total amount of annual precipitation major precipitation regimes of the world are as follows :

(i) The equatorial belt, the windward slopes of the mountains along the western coasts in the cool temperate zone and the central areas of the monsoon lands, receive heavy precipitation of over 200 centimetres per annum.

(ii) Areas adjacent to high precipitation region receive moderate rainfall varying from 100-200 cm. per annum. The coastal area in the warm temperate zone also receive moderate amount of rainfall.

(iii) The central parts of the tropical lands and the center and interior parts of the temperate lands receive inadequate precipitation varying between 50-100 cm. per annum.

(iv) Areas lying in the rain shadow regions. The interior of the continents and high latitudes receive low precipitation of less than 50 cm. per annum. The western margin of the continents in the tropical lands, and the arid deserts come under this category.

(ii) What are forms of condensation? Describe the process of dew and frost formation.
Answer:
Transformation of water vapour into water is called condensation. Condensation is caused by the loss of heat. In free air, condensation results from cooling around very small particles termed as condensation nuclei. Condensation, therefore, depends upon

• the amount of cooling and
• the relative humidity of the air. Condensation is influenced by volume of air, temperature, pressure and humidity.

After condensation, the water vapour or the moisture in the atmosphere takes one of the following forms: dew, frost, fog and clouds. Forms of condensation can be classified on the basis of temperature and location.

Dew: When the moisture is deposited in the form of water droplets on cooler surfaces of solid objects such as stones, plant leaves, etc., it is known as dew. The ideal conditions for the formation of dew are clear sky, calm air, high relative humidity, and cold and long nights. For the formation of dew, the dew point is above freezing point.

Frost: Frost forms on cold surfaces when condensation takes place at a dew point which is at or below freezing point (0°C) when excess moisture is deposited in the form of minute ice crystals instead of droplets of water. The ideal conditions for the formation of white frost are the same as those for the formation of dew, except that the air temperature must be at or below freezing point.

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 10 Atmospheric Circulation and Weather Systems Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Atmospheric Circulation and Weather Systems NCERT Solutions for Class 11 Geography Chapter 10

Atmospheric Circulation and Weather Systems Questions and Answers Class 11 Geography Chapter 10

Question 1.
Multiple choice questions :
(i) If the surface air pressure is 1,000 mb, the air pressure at 1 km above the suface will be –
(a) 700.inb
(b) 1,100 mb
(c) 900 mb
(d) 1,300 mb
Answer:
(c) 900 mb.

(ii) The Inter Tropical Convergence Zone normally occurs
(a) near the equator
(b) near the Tropic of Cancer
(c) near the Tropic of Capricorn
(d) near the Arctic Circle
Answer:
(a) near the equator

(iii) The direction of wind around a low pressure in northern hemisphere is T…………
(a) clockwise
(b) perpendicular to ispbar
(c) anti-clockwise
(d) parallel to isobars
Answer:
(a) clockwise.

(iv) Which one of the following is the source region for the formation of air masses?
(a) the Equatorial Forest
(b) the Himalayas
(c) the Siberian Plain
(d) the Deccan ‘Plateau
Answer:
(b) the Himalayas

Question 2.
Answer the following questions in about 30 words :
(i) What is the unit used in measuring pressure? Why is the pressure measured at station level reduced to the sea level in preparation of weather maps?
Answer:
The atmospheric pressure is expressed in units of mb and Pascals. The widely used unit is kilo Pascal written as hPa. Because, the pressure decreases with height. At any elevation it varies from place to place and its variation is the primary cause of air motion, i.e. wind which moves from high pressure areas to low pressure areas.

(ii) While the pressure gradient force is from north to south, Le. from the subtrophical high pressure to the equator in the northern hemisphere, why are the winds north easterlies in the tropics.
Answer:
The higher pressure gradient force, the more is the velocity of the wind and the larger is the deflection in the direction of wind. The coriolis force acts perpendicular to the pressure gradient force. As a result of these two forces operating perpendicular to each other, in the low pressure areas the wind blows around it. At the equator, the coriolis force is zero and the wind blows perpendicular to the isobars. The low pressure gets filled instead of getting intensified. That is the reason why tropical cyclones are not formed near the equator.

(iii) What are the geotrophic winds?
Answer:
When isobars are straight and when there is no friction, the pressure gradient force is balanced by the Coriolis force and the resultant wind blows parallel to the isobar. This wind is known as the geotrophic wind.

(iv) Explain the land and sea breezes.
Answer:
Pressure gradient from sea to land is created and the wind blows from the sea to the land as the sea breeze. In the night the reversal of condition takes place. The land loses heat faster and is cooler than the sea. The pressure gradient is from the land to the sea and hence land breeze results.

Question 3.
Answer the following questions in about 150 words each :
(i) Discuss the factors affecting the speed and direction of wind.
Answer:
Following three factors affect the speed and direction of the wind :
Pressure of Gradient Force – This is the driving force and wind moves from high pressure to low pressure. This force is produced by the difference in atmospheric pressure.

Frictional Force – The frictional force is present near the earth’s surface. It affects the speed of the wind. It is the greatest at the surface 208 and its influence generally extends. It may effect the direction of surface winds. Over the sea surface, the friction is minimal.

Coriolis Force – It develops due to the rotation of the earth about its axis. It affects the direction of the wind. It deflects the wind to the right in the northern hemisphere and to the left in the southern hemisphere. The deflection is more when the speed of the wind is high. It is maximum at the poles and is absent at the equator.

(ii) Draw a simplified diagram to show the general circulation of the atmosphere over the globe. What are the possible reasons for the formation of subtropical high pressure over 30°N and S latitudes?
Answer:

There are two intermediate zones of sub-tropical highs in the vicinity at 30°N and S and two sub-polar lows in the vicinity at 60°N and S.

The sub-tropical high pressure is located between the tropics on 25° to 3J° north and south latitudes. A calm conduction is erected in this region. These regions are also called horse latitudes because in early days the sailing vessels with horses found it difficult to sail under such calm conditions. These are controlled by pressure gradient and rotation of the earth. Two factors are responsible for general subsistence of air belts.

The warm air of the equatorial low pressure belt gradually gets in its ascent. On reaching upper layers, it slants, moving towards the poles. It further cools and begins to subside in a zone between 20° and 35° latitudes. Among two factors, first, cooling of the air results in increased / density, which accounts for its subsidence.

Second, owing to the rotation of the earth from west to east, poleward directed winds are deflected eastwards. Because of the subsidence of air, the areas between the tropics and 35°N and S develop into high pressure belts. The winds coming from the sub-tropic and polar areas converge in the zone between 45°N and S and the Arctic and Antarctic circles respectively.

(iii) Why does tropical cyclones originate over the seas? In which part of the tropical cyclone do torrential rains and high velocity winds blow and why?
Answer:
Tropical cyclones are notorious for their violence and for causing widespread destruction. These develop over oceans, particularly in tropical regions. Hence, their major climatic significance is in causing widespread rainfall. Most of the tropical cyclones develop in a belt of 8° to 15° north and south latitudes.

Tropical cyclones are characterised by circular and asymmetrical isobars. They have very low pressure at the centre, and the pressure gradient is very steep and winds are very strong. Their velocity ranges between 170-200 km per hour. Rainfall is torrential and is evenly distributed around the centre. They move from east to west with the trades. They are most prominent in the Pacific ocean.

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 9 Solar Radiation, Heat Balance and Temperature Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Solar Radiation, Heat Balance and Temperature NCERT Solutions for Class 11 Geography Chapter 9

Solar Radiation, Heat Balance and Temperature Questions and Answers Class 11 Geography Chapter 9

Question 1.
Multiple choice questions :

(i) The sun is directly overhead at noon on June 21 at
(a) The equator
(b) 23.5°S
(c) 23.50°S
(d) 66.5°N
Answer:
(d) 66.5°N.

(ii) In which one of the following cities are days the longest?
(a) Tiruvanantpuram
(b) Chandigarh
(c) Hyderabad
(d) Nagpur
Answer:
(d) Nagpur.

(iii) The atmosphere is mainly heated by the ………..
(a) Short wave Solar radiation
(b) Reflected solar radiation
(c) Long wave terrestrial radiation
(d) Scattered solar radiation
Answer:
(c) Long wave terrestrial radiation.

(iv) Make correct pairs from the following two columns :

Answer:
1. (c), 2. (d), 3. (b), 4. (a).

(v) The main reason that the earth experiences highest temperatures in the subtropics in the northern hemisphere rather than at the equator is :
(a) Subtropical areas tend to have less cloud cover than equatorial areas.
(b) Subtropical areas have longer day hours in the summer than the equatorial.
(c) Subtropical areas have an enhanced ‘green house effect’ compared to equatorial areas.
(d) Subtropical areas are nearer to oceanic areas than equatorial locations.
Answer:
(c) Subtropical areas have an enhanced ‘green house effect’ compared to equatorial areas.

Question 2.
Answer the following in about 30 words each :
(i) How does the unequal distribution of heat over the planet earth in space and time cause variations in weather and climate?
Answer:
The amount of heat received by different parts of the earth is not the same. This variation causes pressure differences in the atmosphere. This leads to transfer of heat from one region to the other by winds.

(ii) What are the factors that control temperature distribution on the surface of the earth?
Answer:
The factors controlling temperature distribution are :

• Latitude
• Altitude
• Land and water
• Prevailing winds
• Ocean currents

(iii) In India, why is the day temperature maximum in May and why not after summer solstice?
Answer:
Because in May, the North Pole is inclined 23’A° toward the sun. As a result, the sun’s rays are vertical at noon over Tropic of Cancer. The sun is always above the horizon throughout the day north of 66!/2°N. So the North polar region experiences six months of sunlight in the summer. The northern hemisphere has longer day hours in summer.

(iv) Why is the annual range of temperature high in the Siberian plains?
Answer:
Annual range of temperature is the difference between the mean temperature of the hottest month and the mean temperature of the coldest month.

It is much pronounced in Siberian plain. The mean January temperature along 60°E longitude is – 20°C both at 80°N and 50°N latitudes. The mean monthly January temperature is over 27°C in equatorial oceans, over 24°C in the tropics, and 2°C to 0° in middle latitudes and -18°C to -48°C in Eurasian continental interior.

Question 3.
Answer the following questions in about 150 words each :

(i) How do the latitude and the tilt in the axis of rotation of the earth affect the amount of radiation received at the surface.
Answer:
The latitude determines the angle of inclination of solar rays. At the equator, the solar rays are nearly vertical and their inclination decreases towards the poles. Between the Tropic of Cancer 23 ‘/2°N and the Tropic of Capricorn (23’/2°S), the solar rays fall vertically twice a year. On any day the inclination of solar rays decreases away from the latitude where the sun is overhead at noon.

Another factor that determines the amount of insolation received at a place is the length of the day. The variation in day length in a year is caused by the tilt of axis of rotation of earth and the revolution of the earth around the sun. The axis of rotation of earth is inclined about 66V20 from the plane of ecliptic.

On March 21st and September 23rd, the sun is overhead at noon over the equator. On these dates the days are 12 hours long all over the world.

On about June 21st, the North pole is inclined 23’A0 towards the sun. As a result, the sun’s rays are vertical at noon over the Tropic of Cancer.

On about December 21st, sun’s rays are vertical over Tropic of Capricorn. The southern hemisphere experiences longer day hours and northern hemisphere experiences shorter day duration.

(ii) Discuss the processes through which the earth atmosphere system maintains heat balance.
Answer:
There are variations in the amount of radiation received at the earth’s surface caused by variation in angle of incidence of sun’s rays, the length of the day and presence of clouds. In the net result, some part of the earth has surplus radiation balance and some other part has deficit radiation balance in the surface atmosphere.

The mean annual temperature of the earth as a whole remains the same. But balance between incoming and outgoing radiation is not uniform and varies from latitude to latitude. In the low latitudes (between 40°N and 40°S) heat gained by shortwave radiation is far more than the heat lost by long wave through the earth’s radiation. While in the higher latitudes, more heat is lost by outgoing long wave than received in short waves.

(iii) Compare the global distribution of temperature in January over the northern and the southern hemisphere of the earth.
Answer:
The global distribution of temperature is generaly shown on the map as isotherms. The deviation from this general trend is more pronounced in January than in July, especially in the northern hemisphere. In the northern hemisphere, the land surface area is much larger than in the southern hemisphere.

Hence, the effects of landmass and the ocean currents are well pronounced. In January the isotherms deviate to the north over the ocean and to south over the continent. The pressure of warm ocean currents, gulf stream and North Atlantic drift make the Northern Atlantic warmer and the isotherms bend towards the north. Temperature decreases over the land and the isotherms bend towards south in Eurasian continent.