Class 9 Social Science II: Chapter 01 Sun: The Ultimate Souce - Questions and Answers

Textbooks Solution for Class 9th Social Science II (English Medium) സര്‍വ്വവും സൂര്യനാല്‍  | Text Books Solution Geography (English Medium) Geography: Chapter 01 Sun: The Ultimate Souce


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Class 9 Geography Questions and Answers
Sun: The Ultimate Souce - Questions and Answers & Model Questions
1. What is insolation?
• Solar energy reaches the earth in the form of short waves. This is called Insolation.

2. What are the different processes of heat transfer in the atmosphere?
   OR
The various processes of heat transfer in the atmosphere are indicated by the diagram given below. Examine the diagram and identify each process
a) Conduction -Heat is transferred to that part of the atmosphere close to the hot surface of the earth.
b) Convection -Heated air expands and rises up
c) Advection -Horizontal transfer of heat through the wind.
d) Terrestrial Radiation- Heat is transferred from the surface of the earth to outer space in the form of long waves.

3. What is the difference between insolation and terrestrial radiation?
• Solar energy reaches the earth in the form of short waves. This is called Insolation.
• Heat is transferred from the surface of the earth to outer space in the form of long waves.

4. Why does terrestrial radiation occur mostly at night?
• During the daytime, there is a net gain in energy due to radiation from the Sun. While in the night, when sunlight is absent, there is a net loss in energy. The Earth's crust has a limit to absorb energy. Hence, Terrestrial radiation occurs mostly at night.

5. What is the heat budget?
• The balance between insolation and terrestrial radiation is called heat budget

6. What do you meant by temperature? Which is the instrument used to measure temperature?
• Temperature is the degree of hotness of the atmosphere. Thermometer.

7. Why the maximum temperatures are being recorded at 2pm?
• Maximum temperature of the atmosphere is felt at about 2 in the afternoon because it takes about two hours to heat the atmosphere by terrestrial radiation.

8. What is the difference between the diurnal range of temperature and the daily mean temperature?
• The difference between the maximum and the minimum temperatures of a day is called the diurnal range of temperature.
           Diurnal range of temperature = maximum temperature of the day – minimum temperature of the day
• The average temperature of a day is termed daily mean temperature'.
            Daily mean temperature =
Maximum temperature + Minimum temperature of the day
                                           2

9. What are isotherms?
• The imaginary lines connecting places having equal atmospheric temperature are called isotherms.

10. What are the factors influencing the distribution of temperature?
i. Latitude
 - The region receives more energy as the sun's rays are almost vertical. As latitude increases, temperature decreases
ii. Altitude
 - The temperature is comparatively lower at places situated much above sea level. As altitude increases temperature decreases
iii. Nearness of ocean
- Temperature will be higher at places away from the sea and temperature
remains moderate at places close to the sea.
iv. Wind
-  The warm winds raise the temperature and the cold winds can lower the temperature.

11. The temperature in the troposphere decreases at the rate of 1° C per 165 m of altitude. What is this process called?
• Normal lapse rate.

12. The temperature experienced in places like Idukki and Wayanad is much lower than that of the neighbouring districts Ernakulum and Kozhikode respectively. Why?
• Idukki and Wayanad are places having a higher altitude (height) than their neighbouring districts of Ernakulam and Kozhikode
13. Generally Kerala experiences moderate temperatures. Why?
• Temperature remains moderate at places close to the sea. Because of the influence of The Arabian Sea to the west  Kerala experiences moderate temperature.

14. Isotherms in the southern hemisphere are almost parallel to the Equator compared to those in the northern hemisphere. Why?
• In the southern hemisphere we have more water mass as compared to landmass and hence isotherms are regular in nature. The bending of isotherms is due to the differential heating of land and water. That is why Isotherms in the southern hemisphere are almost parallel to the Equator compared to those in the northern hemisphere.

15. In the weather maps for the summer and winter seasons, the isotherms behave differently. Why?
• The isotherms are more linear (straight across) in the Southern Hemisphere. Large landmasses in the Northern Hemisphere cause isotherms to bend toward the equator in winter and poles in summer as they change their temperature much more than the water.

16. What is humidity? Is humidity uniform in all places?
• Water content in the atmosphere is called humidity.
• No. Humidity varies with place and time.

17. Explain the following words
a) Absolute Humidity-The actual amount of water present in the atmosphere is called absolute humidity
b) The saturation level-The stage at which the atmosphere is fully saturated with water is termed as the saturation level.
c) Dew point- The critical temperature at which condensation begins is called the dew point.
d) The relative humidity- The ratio between the amount of water vapour present in the atmosphere and the total water holding capacity of the atmosphere at a given temperature is called  relative humidity
    Relative humidity =  Absolute humidity × 100
Total water holding capacity of the atmosphere at that particular temperature

18. Name the instrument used to measure relative humidity?
• wet and dry bulb thermometer.

19. What are the different forms of condensation?
a) Dew -The water droplets clinging to the blades of grass and leaves early in the morning. 
b) Frost -Places on the earth were the night temperature falls below 0°C tiny ice crystals are formed.
c) Fog or Mist -The condensed tiny droplets of water formed by the cooling of air remain suspended in the atmosphere during winter. If the range of visibility is less than one kilometre, it is termed fog. If the range of visibility is more than one kilometre, it is called mist.
d) Clouds- Formed by the condensation of water vapour around the fine dust particles in the atmosphere.

20. Clouds can be classified according to their form and height. Explain
(i) Cirrus clouds: These are feather-like clouds in the upper atmosphere in clear weather conditions.
(ii) Stratus clouds: These appear in thick layers in the lower part of the sky.
(iii) Cumulus clouds: These clouds resemble huge cotton bundles and are formed due to strong convection currents. They have a large vertical extent.
(iv) Nimbus clouds: These are dark rain clouds in the lower atmosphere. These clouds appear dark as it does not allow sunlight to pass through due to the thick concentration of water droplets.

21. Which are the four different types of clouds based on altitude?
• High clouds (20000 to 40000 ft)
• Medium clouds (7000 to 20000 ft)
• Low clouds (< 7000 ft)
• Clouds with great vertical extent(2000 to 30000 ft)

22. What is precipitation? What are the different forms of precipitation?
• Continuous condensation causes the droplets in the clouds to grow in size. Being unable to resist the gravitational force of the earth the water droplets get released from the clouds and fall on the earth in different forms. This process is called precipitation.
a) Rainfall: The common manifestation of precipitation is in the form of water drops.
b) Snowfall: When the temperature falls below 0° Celsius, the precipitation reaches the earth in the form of tiny crystals of ice.
c) Hailstones: If the water droplets released from the clouds happen to pass through colder layers of the atmosphere, they may reach the earth in the form of ice pellets.

23. Explain the different types of rainfall based on their formation?
a) Orographic rainfall or Relief rainfall: Moisture-laden wind from the sea enters the land and moves upwards along the mountain slopes where it gets cooled and condensed to form clouds. When the windward sides of the mountain receive heavy rainfall, the leeward sides do not receive rainfall due to the descending dry air.
b) Convectional rainfall: Cumulus clouds are formed by the cooling and condensation of rising warm air. Rainfall occurs with thunder and lightning. This rain, mostly occurring in the afternoon, does not last long.
c) Border rain: There is always a difference in the atmospheric temperature over land and sea. If the air over the sea comes in contact with the air over the land in the coastal regions, the warm air will be pushed upwards causing cloud formation and rainfall.

24. What do you meant by Rainshadow regions?
• The places situated at the leeward side of the mountains that do not receive any rainfall are referred to as rain shadow regions. 

Practise Questions and Answers
25. If the sea level temperature is 30ºC, what will be the temperature at 330 m altitudes?
• The temperature in the troposphere decreases at the rate of 1° C per 165 m of altitude.
For 330 m altitudes, there is a difference of 2º C
30º - 2º = 28º C

26. Why the South-West monsoon rainfall is not received in Tamil Nadu?
• Tamil Nadu is situated in the rain shadow region of Western Ghats.

27. Which of the following latitudes receive the most intense sunlight?
a. Antarctic Circle
b. Tropic of Capricorn
c. South Pole
d. The Arctic Circle
Answer: Tropic of Capricorn

28. Arrange the given latitudes in the order of a decrease in the availability of solar energy.
Equator - North Pole - Arctic Circle – Tropic of cancer
Answer: Equator - Tropic of cancer- Arctic Circle- North Pole

29. Why are the maximum and minimum temperatures measured at 2 pm and just before sunrise, respectively?
• The earth's surface is heated by insolation. The atmosphere gets heated from the earth by conduction and convection. It attains its maximum temperature by 2 pm only.
​
30. Why are the isotherms generally curved in the northern hemisphere?
• Comparatively land area is more than the ocean in the Northern Hemisphere.
• The isotherms are generally curved because of the differential heating of land and sea.

31. Explain the following concepts in relation to atmospheric humidity.
A)  Absolute humidity
B)  Saturation level
C)  Relative humidity
Answer:
A) The actual amount of water present in the atmosphere is called absolute humidity.
B) The stage at which the atmosphere is fully saturated with water is termed the saturation level.
C) The ratio between the amount of water vapour present in the atmosphere and the total water holding capacity of the atmosphere at a given temperature is called relative humidity.

32. Identify the forms of condensation from the given hints.
i) Water droplets clinging on the blades of grass and leaves early mornings.
ii) Condensation around the minute dust particles in the lower layers of the atmosphere.
Answer:
i) Dew
ii) Fog

33. Below are some hints related to clouds. Observe the hints and identify the clouds.
A) Dark clouds are seen in the lower atmosphere
B) Feather like clouds in the upper atmosphere in clear weather.
Answer:
A) Nimbus clouds
B) Cirrus clouds

34. Name the clouds situated at an altitude of 7000 to 20000 ft.
• Medium clouds

35. Examine the given map and answer the following questions.
a. What do the curved lines in the map indicate?
b. Write your inferences on the distribution of temperature.
Answer:
a. isotherms
b. From South to North, temperature increases.

36. A) Arrange Idukki, Kozhikode, Wayanad and Ernakulam as per the indicators given below.
B) B. What causes this kind of variations in temperature?
- High Temperature
- Low Temperature
Answer:
A.
High Temperature
- Kozhikode
- Ernakulam
Low Temperature
- Idukki
- Wayanad
B. Altitude from sea level

37. Which form of rainfall is common in the equatorial climate zone?
• Convectional rainfall

38. Analyse the table given below and write inferences.
• The temperature is not uniform all over India on the same day.
• Temperature at any place varies over time.

39. Why temperature remains moderate at places close to the sea?
• This is because the heating of land causes the wind to blow from sea to land and the cooling of land causes the wind to blow from land to sea. so Moderate temperatures prevail in areas close to the sea.

40. Examine the given diagram of the Heat Budget and write any three inferences.
Answer:
51 per cent absorbs the Earth's surface.
14% absorb clouds and dust.
About 17% of the terrestrial radiation directly reaches the atmosphere.

41. Analyze the given maps and write down any two conclusions related to temperature.
- Temperatures in different places on the same day are not the same.
Temperatures in one area at different times are not the same.
Local and seasonal variations in temperature (any two)

42. Examine the given news headlines and find out how the winds influence the temperature of an area.
- The warm and the cold winds can respectively raise or lower the temperature of the places through which they pass.

43. Write the difference:
(a) Dew and Frost
(b) Mist and Fog
Answer:
a) Dew: condensation of water vapour by the cooling of the atmosphere at night and the cold surfaces of the earth.
Frost: Instead of dew, tiny ice crystals are formed in areas where the surface temperature falls below zero degrees during the night.
(b) If the range of visibility is less than one kilometre, it is termed as fog and more than one kilometre, it is called mist.



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