The rest of the insolation is absorbed by which components?

• A. Ozone
• B. Nitrogen
• C. Water vapour, dust, clouds
• D. Carbon dioxide

Answer: (C)

Sunlight that reaches Earth must pass through the atmosphere, where a large portion is reflected or scattered, and the remainder is absorbed by atmospheric constituents. The main absorbers of the sun’s shortwave energy are water vapor, dust, and clouds. Water vapor in the air absorbs parts of the solar spectrum and converts that energy to heat. Clouds—composed of liquid droplets or ice—both reflect some sunlight and absorb a significant amount, especially in thicker clouds, warming the air below. Dust particles also absorb and scatter sunlight, reducing the amount reaching the surface. Ozone mainly blocks ultraviolet radiation, not the bulk of the visible and near-infrared solar radiation, while nitrogen is largely transparent and carbon dioxide plays a smaller role in shortwave absorption compared with water vapor, dust, and clouds.