Solar Radiation, Heat Balance and Temperature Short and Long Important Question Class 11 Geography Chapter-8 Book-Fundamental of Physical Geography
0Team Eklavyaजून 11, 2025
1. What is solar radiation?
Answer:
Solar radiation is the energy that radiates from the Sun to the Earth. It is also called insolation. It reaches the Earth mainly in short wavelengths.
2. Why does the Earth not receive the entire energy of the Sun?
Answer:
The shape of the earth is not completely round but is in the form of a "geoid", due to which the sun rays fall obliquely instead of straight.
The atmosphere absorbs some of the sun's energy and reflects some back into space.
The Earth's distance from the Sun keeps changing, which affects the energy obtained.
3. What are aphelion and perihelion?
Answer:
Aphelion: When the Earth is farthest from the Sun (about 152 million km) – this occurs on July 4.
Perihelion: When the Earth is closest to the Sun (about 147 million km) – this occurs on January 3.
4. What are the factors affecting insolation on the earth?
Answer:
Angle of the sun rays: Direct rays provide more heat, while oblique rays provide less heat.
Length of day: Longer days receive more insolation.
Atmospheric transparency: Dust, water vapor, and gases can absorb or scatter insolation.
The shape of the Earth's surface: the distribution of mountains, plains and oceans affects insolation.
Axial Tilt: The tilt of 66½° changes the amount of insolation at different latitudes.
5. How does solar radiation pass through the atmosphere?
Answer:
Some of the sun's rays are absorbed by the atmosphere.
Oblique rays scatter more because they travel a greater distance.
This is why the sky appears red at sunrise and sunset and blue during the day.
6. Which place receives the highest and lowest sunlight?
Answer:
Highest in: the tropics (about 320 W/m²), especially desert regions (such as the Sahara), where cloud cover is low.
Lowest: Polar regions (about 70 W/m²), because the sun's rays are more oblique here.
7. How does the Earth's atmosphere heat up and cool down?
Answer:
Conduction: The air is heated by contact with the Earth's surface.
Convection: Warm air rises and cool air descends, causing temperature to be transferred.
Advection: The movement of temperature from one place to another due to the horizontal flow of air.
Terrestrial Radiation: The earth radiates the energy received from the sun in the form of long waves.
Radiation: The atmosphere and Earth's surface release energy into space as radiation.
8. What is the heat budget of the Earth?
Answer:
It shows how much energy the Earth receives from the Sun and how much is reflected back into space.
Out of 100 units:
35 units are reflected and returned into space.
14 units are absorbed by the atmosphere.
51 units are absorbed by the earth's surface.
Eventually 65 units return to space, maintaining the energy balance.
9. What are the main factors affecting temperature?
Answer:
Latitude: Higher temperature at the equator, lower at the poles.
Altitude: The temperature decreases as we go higher above sea level.
Distance from the sea: Temperatures remain stable near the sea, while inland temperatures fluctuate more.
Ocean Currents: Warm currents increase the temperature, cold currents decrease it.
Local effects: Vegetation, clouds, and urbanization affect temperature.
10. What is Temperature Inversion?
Answer:
Generally the temperature decreases with altitude, but in some situations the temperature starts increasing, this is called temperature inversion.
This occurs more frequently on winter nights, when the Earth's surface cools and the air above remains relatively warm.
This causes fog and smoke to get trapped near the surface, which can increase pollution.
11. What is surplus and deficit in heat budget?
Answer:
More sunlight is received between 40° north and south latitudes, due to which there is a surplus of heat here.
Polar regions receive less sunlight, which causes a heat deficit here.
Atmospheric wind and ocean currents maintain the temperature balance by transporting surplus heat to the poles.
12. What is the difference in temperature distribution in January and July?
Answer:
January: The temperature in the Northern Hemisphere shows more variation because there is more land mass. In the Southern Hemisphere, the temperature remains stable because of the oceans.
July: Temperatures are high in the Northern Hemisphere, as it is summer.
13. Where is the maximum and minimum temperature difference found on the earth?
Answer:
Maximum temperature difference: In North-Eastern Eurasia, where the temperature difference is up to 60°C.
Minimum temperature difference: In equatorial regions, where the temperature difference is only up to 3°C.
14. Why does temperature differ across oceans and continents?
Answer:
The oceans heat and cool slowly, keeping their temperature constant.
Temperatures fluctuate more in continental regions as land areas heat and cool faster.
15. What scales are used to measure temperature changes?
