Normally, the temperature decreases with the increase in height from the Earth’s surface, because 1. the atmosphere can be heated upwards only from the Earth’s surface 2. there is more moisture in the upper atmosphere 3. the air is less dense in the upper atmosphere Select the correct answer using the codes given below:

QUESTION

Medium

Physical Geography

Prelims 2012

Normally, the temperature decreases with the increase in height from the Earth’s surface, because

the atmosphere can be heated upwards only from the Earth’s surface
there is more moisture in the upper atmosphere
the air is less dense in the upper atmosphere

Select the correct answer using the codes given below:

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Explanation

The decrease in temperature with increasing altitude in the troposphere is known as the Normal Lapse Rate (roughly 6.5°C per 1,000 meters). This occurs because:

Statement 1 is correct: The atmosphere is largely transparent to incoming short-wave solar radiation. It is primarily heated from below by long-wave terrestrial radiation (heat radiated back from the Earth’s surface). Therefore, layers closer to the ground are warmer.

Statement 2 is incorrect: Most of the atmosphere's moisture (water vapor) and dust particles are concentrated in the lower layers. These elements are responsible for trapping terrestrial heat. The upper atmosphere is significantly drier and thinner.

Statement 3 is correct: At higher altitudes, the air pressure is lower, making the air less dense. When air from the surface rises, it expands due to the lower pressure. This expansion requires work, which consumes the internal energy of the air parcel, causing its temperature to drop. This is known as adiabatic cooling. Additionally, thinner air has a lower capacity to absorb and retain heat.

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