With reference to the Earth's atmosphere, which one of the following statements is correct?
Correct Answer: Option C
The Earth receives most of its energy in short wavelengths, known as insolation.
The insolation at the equator is approximately 320 Watt/m2, while at the poles it's about 70 Watt/m2. Therefore, the equator receives roughly 5 times the insolation of the poles, not 10 times.
Statement a is incorrect.
Insolation is primarily shortwave radiation within the ultraviolet and visible portions of the electromagnetic spectrum (0.39 to 0.76 micrometres). Radiation emitted by the Earth is long-wave radiation in the infrared portion (4 to 30 micrometres). Thus, infrared rays do not constitute two-thirds of insolation.
Statement b is incorrect.
The atmosphere is largely transparent to shortwave solar radiation. Within the troposphere, water vapor, ozone, and other gases absorb much of the near-infrared radiation.
Water vapor, the most abundant greenhouse gas, strongly absorbs infrared radiation in the lower atmosphere.
Statement c is correct.
Infrared waves are not part of the visible spectrum. The visible spectrum ranges from approximately 400 to 700 nanometers, while infrared waves have wavelengths longer than 700 nanometers.
Statement d is incorrect.
Hence, only statement c is correct.
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