NCERT Class 11 Geography Fundamental of Physical Geography: Chapter 8 — C H A P T E R
This chapter from NCERT's Fundamental of Physical Geography for Class 11 delves into Solar Radiation, Heat Balance, and Temperature. It explains how the Earth receives energy from the sun, the variations in this insolation due to factors like Earth's revolution, axial tilt, and atmospheric transparency. The text details the processes of heating and cooling the atmosphere through conduction, convection, and advection, and the role of terrestrial radiation. It also touches upon the spatial distribution of insolation across the Earth's surface, influenced by latitude, cloudiness, and land-sea distribution. Understanding these concepts is crucial for comprehending atmospheric phenomena and climate patterns, aiding students in their CBSE Geography studies.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Geography |
| Book | Fundamental of Physical Geography |
| Chapter | Chapter 8 — C H A P T E R |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 6 minutes |
| Word count | 1075 |
Learning outcomes
- Explain the variation in insolation received at the Earth's surface.
- Describe the processes of heating and cooling of the atmosphere.
- Understand the role of solar and terrestrial radiation in Earth's energy balance.
- Analyze the spatial distribution of insolation across different latitudes.
- Identify factors influencing temperature distribution on Earth.
Vocabulary
| Word | Meaning |
|---|---|
| Insolation | Incoming solar radiation received at the top of the atmosphere or at the Earth's surface. |
| Aphelion | The position of the Earth farthest from the Sun during its revolution (around July 4th). |
| Perihelion | The position of the Earth nearest to the Sun during its revolution (around January 3rd). |
| Conduction | Transfer of heat through direct contact between particles of unequal temperature. |
| Convection | Transfer of heat through the vertical movement of heated air currents. |
| Advection | Transfer of heat through the horizontal movement of air. |
| Terrestrial Radiation | The long-wave radiation emitted by the Earth's surface after being heated by insolation. |
| Scattering | The process by which small particles in the atmosphere disperse solar radiation in different directions. |
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Practice questions
- What is insolation? Answer: Insolation is the incoming solar radiation received by the Earth.
- What are aphelion and perihelion? Answer: Aphelion is when Earth is farthest from the Sun, and perihelion is when it is nearest.
- Name the three main processes of heating and cooling of the atmosphere. Answer: The three main processes are conduction, convection, and advection.
- How does latitude affect the amount of insolation received? Answer: Higher latitudes receive less insolation because the sun's rays are more slanted and pass through a greater depth of the atmosphere.
Practice MCQs
Q1. On which date is the Earth farthest from the Sun?
Explanation: The Earth is farthest from the Sun on July 4th, a position known as aphelion.
Q2. Which process involves the transfer of heat through the vertical movement of air?
Explanation: Convection is the process where heat is transferred through the vertical movement of heated air currents.
Q3. The Earth receives most of its energy in which wavelength form?
Explanation: The Earth's surface receives most of its energy from the sun in the form of short wavelengths.
Q4. What causes the blue color of the sky?
Explanation: The blue color of the sky is a result of the scattering of sunlight by small particles in the atmosphere.
Q5. Which position of the Earth is nearest to the Sun?
Explanation: Perihelion is the term used when the Earth is at its closest point to the Sun in its orbit.
Frequently asked questions
What is the difference between aphelion and perihelion?
Aphelion is the point in Earth's orbit where it is farthest from the Sun (around July 4th), while perihelion is the point where it is closest (around January 3rd).
Does the distance variation between Earth and Sun significantly affect daily weather?
No, the effect of the variation in distance between Earth and Sun is masked by other factors like land-sea distribution and atmospheric circulation, so it doesn't greatly affect daily weather changes.
What is insolation and how is it measured?
Insolation is the incoming solar radiation. On average, the Earth receives about 1.94 calories per sq. cm per minute at the top of its atmosphere.
How does latitude influence the amount of insolation received?
Higher latitudes receive less insolation because the sun's rays are more slanted, covering a larger area and passing through more atmosphere, leading to greater absorption and scattering.
Explain the process of conduction in heating the atmosphere.
Conduction occurs when the air in contact with the heated Earth's surface absorbs heat directly. This heat is then transferred to the upper atmospheric layers through contact.
What is advection and where is it most important?
Advection is the transfer of heat through the horizontal movement of air. It is particularly important in causing diurnal variations in daily weather in middle latitudes.
What causes the red color of the rising and setting sun?
The red color of the rising and setting sun is caused by the scattering of light within the atmosphere, where shorter wavelengths (like blue) are scattered away more effectively, leaving longer wavelengths (like red) visible.
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NCERT Class 11 Geography — Fundamental of Physical Geography — Chapter 8 — C H A P T E R. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.