(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.
Ans: c
Explanation:
Maximum insolation is over the subtropical deserts as the cloudiness is the least here. The insolation received at the surface varies from about 320 watts/m2 in the tropics to about 70 watts/m2 in the poles. The Equator receives comparatively less insolation even than the tropics (less than 320 watts/m2). So, even if the insolation is greater at the equator than at the poles, it’s not 10 times larger.
Hence, statement 1 is incorrect.
Insolation includes a broad spectrum of electromagnetic radiation in the form of visible light, ultraviolet (UV) radiation, and other wavelengths as well. While infrared radiation is a significant component of solar radiation, it does not account for two-thirds of the insolation.
Hence, statement 2 is incorrect.
Water vapour is a potent absorber of infrared radiation, particularly in certain wavelength bands. In the lower atmosphere, where water vapour concentration is relatively higher, it absorbs a significant amount of infrared radiation emitted by the Earth’s surface. This absorption contributes to the greenhouse effect and plays a crucial role in regulating the Earth’s temperature.
Hence, statement 3 is correct.
Infrared waves and visible light waves form the different parts of the electromagnetic spectrum. The visible spectrum ranges from around 400 to 700 nanometers and includes the colours we perceive. Infrared radiation, on the other hand, has longer wavelengths than visible light and is not visible to the human eye. It lies just beyond the red end of the visible spectrum and is typically divided into near-infrared, mid-infrared, and far-infrared regions based on wavelength.
Hence, statement 4 is incorrect.
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