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Looking for NCERT Class 11 Geography Chapter 8 Solar Radiation, Heat Balance and Temperature Solutions? This guide provides clear, concise answers to all exercise questions from Chapter 8 of the Fundamentals of Physical Geography textbook. These solutions are designed to help you understand key concepts, prepare for exams, and excel in class discussions. Download the free PDF to revise anytime.
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NCERT Solutions Class 11 Geography Fundamentals of Geography Chapter 8: Solar Radiation, Heat Balance and Temperature
These NCERT solutions for Class 11 Geography Chapter 8 will help you master the concepts of solar radiation, heat balance, and temperature distribution. Regular revision of these answers will boost your exam performance.
1. Multiple Choice Questions
(i) The sun is directly overhead at noon on 21st June at:
(a) The equator
(b) 23.5° S
(c) 23.5° N
(d) 66.5° N
(ii) In which one of the following cities, are the days the longest?
(a) Thiruvananthapuram
(b) Chandigarh
(c) Hyderabad
(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
(iv) Make Correct Pairs from the Following Two Columns:
| Column A | Column B |
| (i) Insolation | (a) The difference between the mean temperature of the warmest and the coldest months |
| (ii) Albedo | (b) The lines joining the places of equal temperature |
| (iii) Isotherm | (c) The incoming solar radiation |
| (iv) Annual range | (d) The percentage of visible light reflected by an object |
(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 “greenhouse effect” compared to equatorial areas.
(d) Subtropical areas are nearer to the oceanic areas than the equatorial locations.
Solutions:
(i) (c) 23.5° N
On June 21, the summer solstice, the sun is directly overhead at the Tropic of Cancer (23.5° N) due to the Earth’s axial tilt.
(ii) (b) Chandigarh
Chandigarh, located farther north, experiences longer daylight hours during summer compared to cities closer to the equator like Thiruvananthapuram, Hyderabad, or Nagpur.
(iii) (c) Long wave terrestrial radiation
The atmosphere is primarily heated by long wave terrestrial radiation emitted from the Earth’s surface, which is absorbed by greenhouse gases.
(iv) Correct Pairs are
(i) Insolation – (c) The incoming solar radiation
(ii) Albedo – (d) The percentage of visible light reflected by an object
(iii) Isotherm – (b) The lines joining the places of equal temperature
(iv) Annual range – (a) The difference between the mean temperature of the warmest and the coldest months
(v) (a) Subtropical areas tend to have less cloud cover than equatorial areas.
Subtropical regions often have clearer skies, allowing more solar radiation to reach the surface, leading to higher temperatures compared to cloudy equatorial areas.
Also Read:
- NCERT Class 6 Geography Chapter 5 ‘Major Domains of the Earth’: Notes and Solutions (Free PDF)
- NCERT Class 7 Geography Chapter 3 ‘Our Changing Earth’: Notes and Solutions (Free PDF)
2. Answer the Following Questions in About 30 Words
(i) How does the unequal distribution of heat over the planet Earth in space and time cause variations in weather and climate?
Solutions: The unequal distribution of heat due to varying insolation, latitude, and seasons creates temperature differences. These drive atmospheric circulation, pressure systems, and precipitation patterns, causing diverse weather and climate.
(ii) What are the factors that control temperature distribution on the surface of the Earth?
Solutions: Factors include latitude, altitude, distance from the sea, ocean currents, prevailing winds, cloud cover, and surface albedo. These influence the amount of insolation received and heat retention.
(iii) In India, why is the day temperature maximum in May and why not after the summer solstice?
Solutions: In May, India experiences maximum insolation and clear skies before the monsoon. After the summer solstice, monsoon clouds reduce insolation, lowering temperatures despite longer days.
(iv) Why is the annual range of temperature high in the Siberian plains?
Solutions: The Siberian plains, far from oceans, experience extreme continental climate. Summers are warm due to high insolation, while winters are severely cold due to low insolation, causing a high annual temperature range.
3. Answer the Following Questions in About 150 Words
(i) How do the latitude and the tilt in the axis of rotation of the Earth affect the amount of radiation received at the Earth’s surface?
Solutions: Latitude and the Earth’s axial tilt (23.5°) significantly influence the amount of solar radiation received. At lower latitudes (near the equator), the sun’s rays are more direct, concentrating energy over a smaller area, resulting in higher insolation. At higher latitudes, rays strike at oblique angles, spreading energy over a larger area, reducing insolation. The axial tilt causes seasonal variations. During the summer solstice (June 21), the Northern Hemisphere is tilted toward the sun, receiving more direct rays and longer daylight, increasing insolation. In winter, the tilt away from the sun results in oblique rays and shorter days, reducing insolation. This tilt also causes the sun to be overhead at the Tropics (23.5° N/S) during solstices, not the equator, affecting regional radiation patterns. Thus, latitude and tilt determine the spatial and temporal distribution of solar energy, shaping climate zones.
(ii) Discuss the processes through which the Earth-atmosphere system maintains heat balance.
Solutions: The Earth-atmosphere system maintains heat balance through three key processes: radiation, conduction, and convection. The Earth receives short wave solar radiation (insolation), of which about 30% is reflected (albedo), 20% is absorbed by the atmosphere, and 50% reaches the surface. The surface absorbs this energy and emits long wave terrestrial radiation. Greenhouse gases (e.g., CO₂, water vapor) absorb some of this radiation, trapping heat and warming the atmosphere. Conduction transfers heat from the Earth’s surface to the lower atmosphere through direct contact. Convection circulates heat via air movement, with warm air rising and cool air sinking, distributing heat vertically and horizontally. Oceans also play a role by storing and transferring heat through currents. This balance ensures the Earth neither excessively heats nor cools, maintaining a stable average temperature despite regional and seasonal variations, supporting life and climate stability.
(iii) Compare the global distribution of temperature in January over the Northern and Southern Hemispheres of the Earth.
Solutions: In January, the Northern Hemisphere experiences winter due to the Earth’s tilt, with the sun’s rays striking at oblique angles, leading to lower temperatures. High latitudes (e.g., Arctic) have temperatures below -30°C, while mid-latitudes (e.g., Europe, North America) range from -10°C to 10°C. Continental interiors like Siberia are colder due to distance from moderating oceans. Conversely, the Southern Hemisphere is in summer, receiving more direct insolation. Temperatures in mid-latitudes (e.g., Australia, South America) range from 20°C to 30°C, while Antarctica remains cold (below -20°C) due to high albedo and elevation. The Southern Hemisphere has more ocean coverage, moderating temperatures, so extremes are less pronounced than in the Northern Hemisphere’s continental regions. Isotherms in the Northern Hemisphere bend southward over land, while in the Southern Hemisphere, they are more uniform due to oceanic influence, highlighting contrasting temperature patterns.
Also Read:
- NCERT Class 6 Geography: Chapter 2 Latitudes and Longitudes
- NCERT Class 7 Geography Chapter 3 ‘Our Changing Earth’: Notes and Solutions (Free PDF)
Download NCERT Solutions Class 11 Geography Fundamentals of Physical Geography Chapter 8: Solar Radiation, Heat Balance and Temperature
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