Insolation is defined as the solar radiation received in which locations?

• A. In space
• B. In the Earth's core
• C. In the Earth's atmosphere or at its surface
• D. On the Moon

Answer: (C)

Insolation is the solar energy that actually reaches the Earth, either in the atmosphere or at its surface. It’s the amount of sunlight that makes it through space and the atmospheric layers to interact with the planet, driving warming and weather patterns. This energy varies with the sun’s angle, time of day, season, cloud cover, and atmospheric conditions, which is why insolation is higher at midday in sunny locations and lower when the sun is low or obscured.

That’s why the correct phrase describes the energy located in the Earth’s atmosphere or at the surface. Radiation measured in space, or on the Moon, or deep inside the Earth’s core, isn’t described as insolation for Earth-related climate studies.