What percentage of insolation is absorbed by the atmosphere?

• A. 23%
• B. 12%
• C. 15%
• D. 40%

Answer: (A)

The main idea is how incoming solar radiation is split among reflection, absorption by the atmosphere, and absorption by the surface. Globally, about 30% of insolation is reflected back to space (albedo). Of what’s not reflected, roughly 23% is absorbed by the atmosphere, and about 47% is absorbed by the surface. So the atmosphere’s fraction being absorbed is around 23%.

Why this fits: gases like water vapor, CO2, ozone, and clouds absorb portions of the sunlight, heating the atmospheric layer. The rest that isn’t reflected or absorbed by the atmosphere mostly reaches the surface, where it’s absorbed and warms the ground and oceans. The other numbers (12%, 15%, 40%) don’t align with the typical global energy budget breakdown, where a sizable chunk is absorbed by the surface and a substantial portion is reflected, leaving roughly a quarter to the atmosphere.