With reference to the heat balance of the Earth, how is the terrestrial radiation (51 units) returned to space? 1. 17 units are radiated to space directly. 2. 48 units are absorbed by the atmosphere and then radiated back. 3. The atmosphere absorbs terrestrial radiation solely through conduction. Which of the statements given above is/are correct?

The correct option is 1 only Explanation The Earth maintains its temperature through a heat balance, where the amount of heat received from the Sun (insolation) equals the amount lost to space (terrestrial radiation). Assuming the total incoming insolation is 100 units, 35 units are reflected (albedo) and 65 units are absorbed (14 by the atmosphere and 51 by the Earth's surface). The Earth radiates these 51 units back as terrestrial radiation. Statement-wise Analysis: - Statement 1 is Correct: Out of the 51 units of terrestrial radiation emitted by the Earth's surface, 17 units pass directly through the atmosphere and are radiated into space. This occurs through specific spectral ranges known as "atmospheric windows." - Statement 2 is Incorrect: The atmosphere absorbs 34 units of the terrestrial radiation (not 48). These 34 units are absorbed via direct absorption (6 units), convection/turbulence (9 units), and latent heat of condensation (19 units). The figure of 48 units refers to the total radiation emitted by the atmosphere to space, which is the sum of the 14 units absorbed from incoming solar radiation and the 34 units absorbed from terrestrial radiation. - Statement 3 is Incorrect: The atmosphere does not absorb terrestrial radiation solely through conduction. In fact, conduction plays a very minor role, limited to the air layer in direct contact with the surface. The primary modes of heat transfer from the surface to the atmosphere are longwave radiation, convection, and the release of latent heat of condensation. Key Takeaway: The 51 units of terrestrial radiation are returned to space in two parts: 17 units directly and 34 units via the atmosphere (which eventually radiates them out along with the 14 units it absorbed from the sun).

With reference to the heat balance of… - NCERT Class 11 Geography MCQ

NCERT Class 11 Geography — Chapter 2: Solar radiation, heat balance and temperature

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With reference to the heat balance of the Earth, how is the terrestrial radiation (51 units) returned to space?

17 units are radiated to space directly.
48 units are absorbed by the atmosphere and then radiated back.
The atmosphere absorbs terrestrial radiation solely through conduction.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT Fundamentals of Physical Geography · Page 3

Options

A1 and 3 only
B1, 2 and 3
C2 only
D1 only

Did you get this right?

Solution

The correct option is

1 only

Explanation

The Earth maintains its temperature through a heat balance, where the amount of heat received from the Sun (insolation) equals the amount lost to space (terrestrial radiation). Assuming the total incoming insolation is 100 units, 35 units are reflected (albedo) and 65 units are absorbed (14 by the atmosphere and 51 by the Earth's surface). The Earth radiates these 51 units back as terrestrial radiation.

Statement-wise Analysis:

Statement 1 is Correct: Out of the 51 units of terrestrial radiation emitted by the Earth's surface, 17 units pass directly through the atmosphere and are radiated into space. This occurs through specific spectral ranges known as "atmospheric windows."
Statement 2 is Incorrect: The atmosphere absorbs 34 units of the terrestrial radiation (not 48). These 34 units are absorbed via direct absorption (6 units), convection/turbulence (9 units), and latent heat of condensation (19 units). The figure of 48 units refers to the total radiation emitted by the atmosphere to space, which is the sum of the 14 units absorbed from incoming solar radiation and the 34 units absorbed from terrestrial radiation.
Statement 3 is Incorrect: The atmosphere does not absorb terrestrial radiation solely through conduction. In fact, conduction plays a very minor role, limited to the air layer in direct contact with the surface. The primary modes of heat transfer from the surface to the atmosphere are longwave radiation, convection, and the release of latent heat of condensation.

Key Takeaway:
The 51 units of terrestrial radiation are returned to space in two parts: 17 units directly and 34 units via the atmosphere (which eventually radiates them out along with the 14 units it absorbed from the sun).

Your note

More from Chapter 2: Solar radiation, heat balance and temperature

Consider the following statements regarding the insolation received at the Earth's surface: 1. Generally, at the same latitude, insolation is more over the continent than over the oceans. 2. In winter, the middle and higher latitudes receive more radiation than in summer. 3. The subtropical deserts receive more insolation than the equator. Which of the statements given above is/are correct?

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Which of the following is a characteristic of the isotherms in the Southern Hemisphere?

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With reference to the specific heat of land and water, consider the following statements: 1. The variation in temperature over the sea is much greater compared to land. 2. Land heats up and cools down more quickly than the sea. 3. Places near the sea experience extreme temperature variations. Which of the statements given above is/are correct?

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Which of the following is defined as "the energy needed to raise the temperature of one gram of substance by one Celsius"?

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In the context of the heat budget, what percentage of incoming solar radiation is reflected back to space before reaching the earth's surface?

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