Short Question Answers : Solar Radiation, Heat Balance and Temperature | Geography Class 11 - Humanities/Arts PDF Download

Q. 1. What is the speed of sun’s rays ?
Ans. 3 lakh kms per second.

Q. 2. Which is the main source of heat for the earth ?
Ans. Sun.

Q. 3. What is the normal lapse rate of temperature ?
Ans. 1° C for 165 metres.

Q. 4. In which areas is daily range of temperature low ?
Ans. (i) coastal areas (ii) clouded areas.

Q. 5. In which areas is daily range of temperature low ?
Ans. ( i ) In interiors of continents (ii) In deserts.

Q. 6. Which place experiences the highest annual range of temperature ?
Ans. Verkhoyansk (Siberia).

Q. 7. In which natural region, is annual range of temperature low ?
Ans. Equatorial region.

Q. 8. What does the term isotherm mean ?
Ans. Lines of equal temperature.

Q. 9. Name three processes involved in heating the atmosphere.
Ans. Conduction, Convection and Radiation.

Q. 10. What are the two causes of global warming ?
Ans. The burning of fuels and deforestation.

Q. 11. Name the type of climate found in coastal areas.
Ans. Maritime (equable).

Q. 12. Name the type of climate found in interior regions.
Ans. Continental.

Q. 13. Which ocean current makes the climate of N.W. Europe equable ?
Ans. Gulf stream currents.

Q. 14. Which slope is warmer—North facing or South facing ?
Ans. South facing.

Q. 15. Name an effect of global warming.
Ans. Rise in sea level.

Q. 16. ‘The amount of heat received by different parts of the earth is not same’. Explain.
Ans. There is differential heating and cooling of land and water. No part remains hot for a long time.
Similarly, Cooling is not observed for a long time. So the different parts do not have the same amount of temperature.

Q. 17. Name the factors which cause variation in insolation.
Ans. The following factors cause the variation in insolation during a day or a season or in a year :
(1) Rotation of the earth
(2) The angle of inclination of sun’s rays
(3) The length of the day
(4) Transparency of the atmosphere and
(5) Relief of the land.

Q. 18. Explain the difference between insolation and terrestrial radiation.
Ans. Incoming solar radiation on to the earth is called insolation. It is received in short wave length.
The earth in turn radiates the heat back to the atmosphere in long waves. This is called terrestrial radiation.

Q. 19. ‘‘The annual insolation received by the earth on January 3rd is slightly more than the amount received on July 4th.’’ Why ?
Ans. During the revolution around the sun, the earth is farthest from the sun—152 million kms away on July 4th. This position of the earth is called aphelion.
On January 3rd, the earth is nearest to the sun— 147 million kms away. This position is called perihelion. Therefore the annual insolation received by the earth on January 3rd is slightly more than the amount received on July 4th.

Q. 20. What do you mean by Albedo ?
Ans. Insolation is reflected by clouds and the earth.

This combined reflection sends back some insolation into space. This solar radiation is called Albedo.

Q. 21. Define temperature of a place.
Ans. The temperature means degree of hotness of a body. The temperature of a place means the temperature of the air at that place. It is measured in shade of the air up to the height of atleast one metre.

Q. 22. How is atmosphere heated ?
Ans. The atmosphere is not heated directly by the sun’s rays but it is indirectly heated by the radiation of the earth below. Conduction, convection and radiation are the main processes of heating the atmosphere. The land surface is heated by the sun’s rays. The lower layers are heated through outgoing radiation from the land. When the lower layers get heated, these expand and rise upward as convection currents. These distribute the heat of the lower layers to upper layers.

Q. 23. Name the factors which affect the range of temperature of a place.
Ans. ( i ) Latitude
( ii ) Distance from the sea
(iii) Ocean currents
(iv) Prevailing winds
(v) Soils
(vi) Cloudiness.

Q. 24. What is inversion of temperature ?
Ans. Inversion of Temperature. Under normal conditions, the temperature decreases with increasing height at the rate of 1°C per 165 metres. This is known as ‘Normal lapse rate.’ But sometimes, the conditions are reverse so that the temperature increases with height locally  and temporarily. This condition in which the colder air is nearer the earth and the warmer air above is called inversion of temperature.

Q. 25. Explain the importance of insolation.
Ans. Sun is the most important source of atmospheric heat. Sun’s diameter is more than 100 times the Earth’s diameter and a surface temperature of more than 10,000°F. The heat waves radiate from the sun in all directions at a speed 1,86,000 miles per second or 3 lakh kms per second. The solar radiation received by the earth is 1/2000 millionth part of solar output. Yet, this small amount is vital for our existence on the earth. It is estimated that, on the average the earth receives about 1.9 gms. calories per minute per sq. cm. This is known as ‘solar constant’. All the physical phenomena depend upon insolation. Winds and ocean currents originate due to insolation. The earth is habitable only due to insolation.

Q. 26. Explain the Green house effect of atmosphere.
Ans. Atmosphere is heated by the radiation from the earth’s surface below. This action is compared to that of a glass house or green house in which vegetable and flowers are grown in polar areas. Glass house permits radiation to get in but does not allow radiation to escape out. Therefore, glass house is warmer from inside than outside. Atmosphere also acts like a blanket keeping the earth warm. It is known as green house effect of atmosphere. This is due to presence of carbon dioxide in atmosphere. Carbon dioxide has the ability to absorb earth radiation. The carbon dioxide layer acts as a glass roof of the green house. With the increase in carbon dioxide, the temperature of the earth is increasing. Due to this, the year 1955 was the hottest year in India during this century.