Q. Consider the following statements:
Statement – 1: The atmosphere is heated more by incoming solar radiation than by terrestrial radiation.
Statement – 2: Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation.
Which one of the following is correct in respect of the above statements?
Exp) option d is the correct answer.
Statement I is incorrect. Consider that the isolation received at the top of the atmosphere is 100 per cent. While passing through the atmosphere some amount of energy is reflected, scattered and absorbed. Only the remaining part reaches the earth’s surface. Roughly 35 units are reflected back to space even before reaching the earth’s surface. Of these, 27 units are reflected back from the top of the clouds and 2 units from the snow and ice-covered areas of the earth. The reflected amount of radiation is called the albedo of the earth.
The remaining 65 units are absorbed, 14 units within the atmosphere and 51 units by the earth’s surface. The earth radiates back 51 units in the form of terrestrial radiation. Of these, 17 units are radiated to space directly and the remaining 34 units are absorbed by the atmosphere. Thus, the atmosphere is heated more by terrestrial radiation than by incoming solar radiation.
Statement II is correct. The long wave radiation is absorbed by atmospheric gases particularly by carbon dioxide and the other greenhouse gases as they are good absorbers of long wave radiation.
Source: NCERT – Fundamentals of Physical Geography – Chapter: Solar Radiation, Heat Balance and Temperature
