With reference to the Earth's atmosphere, which one of the following statements is correct?
A
The total amount of insolation received at the equator is roughly about 10 times of that received at the poles.
B
Infrared rays constitute roughly two-thirds of insolation.
C
Infrared waves are largely absorbed by water vapour that is concentrated in the lower atmosphere.
D
Infrared waves are a part of visible spectrum of electromagnetic waves of solar radiation.
Correct Answer: Option C
Explanation
1. Statement A: The total amount of insolation received at the equator is significantly higher than that received at the poles due to the higher angle of incidence of solar rays, but it is not roughly 10 times higher. The annual average difference is closer to 2.5 times. Thus, statement (A) is incorrect.
2. Statement B: Insolation consists of about 7-8% ultraviolet radiation, 42-43% visible light, and 49-51% infrared rays. Therefore, infrared rays do not constitute roughly two-thirds (66.7%) of insolation. Thus, statement (B) is incorrect.
3. Statement C: Water vapour, a major greenhouse gas, is primarily concentrated in the lower atmosphere (troposphere). It effectively absorbs certain wavelengths of infrared waves, particularly the longwave radiation emitted by the Earth. This contributes significantly to the greenhouse effect. Thus, statement (C) is correct.
4. Statement D: Infrared waves have wavelengths longer than those of the visible spectrum. They are a distinct part of the electromagnetic waves spectrum, not a part of the visible spectrum. Thus, statement (D) is incorrect.