Consider the following statements:
- High clouds primarily reflect solar radiation and cool the surface of the Earth.
- Low clouds have a high absorption of infrared radiation emanating from the Earth’s surface and thus cause warming effect.
Which of the statements given above is/are correct?
[UPSC Civil Services Exam – 2022 Prelims]
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (d)
Explanation:
- High clouds are often thin and do not reflect very much. They let lots of the Sun’s warmth in. Low clouds are often quite thick and reflect lots of sunlight back to space. The main difference between high and low clouds is that the high clouds are colder. This means that they radiate less energy into space than the lower, warmer clouds. Therefore, high clouds work to “trap” more energy than the low clouds.
- High clouds are not good at reflecting shortwaves. But, they are very good at blocking longwaves. This also traps heat. Thus, high clouds will cause a warming of the Earth’s surface. Low clouds are excellent reflectors. But, they don’t stop the longwave energy from escaping to space. Therefore, low clouds help to cool the Earth.
Therefore, option (d) is the correct answer.
