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Q70 (CDS-I/2013) Geography › World Physical Geography › Atmospheric heat balance Answer Verified

Nearly 30% of the solar radiations return back to the space without contributing anything to the earth's surface temperature. This amount of radiation is known as—

Result
Your answer: —  ·  Correct: C
Explanation

The amount of solar radiation reflected back to space without contributing to the Earth's surface temperature is known as the Earth's albedo [2]. Albedo is defined as the fraction or proportion of incoming solar radiation that a surface reflects [1]. On a global scale, this is often referred to as the planetary albedo. While specific values can vary slightly across sources, it is generally estimated that approximately 30% to 35% of incoming solar energy is reflected back to space by clouds, atmospheric particles, and reflective surfaces like snow and ice [5]. Specifically, the Earth's average planetary albedo is approximately 0.30 to 0.31, meaning about 30-31% of the sun's energy is immediately reflected. In contrast, a black body is a theoretical object that absorbs all radiation, while the tropopause and mesopause are boundaries within the Earth's atmospheric layers.

Sources

  1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > Albedo > p. 283
  2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Heat Budget of the Planet Earth > p. 69
  3. [4] https://mynasadata.larc.nasa.gov/mini-lessonactivity/what-albedo
  4. [5] https://www.nature.com/scitable/knowledge/library/the-global-climate-system-74649049/
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