What is the definition of the intensity of solar radiation?

The intensity of solar radiation is the amount of solar power per unit area. Power is the energy per second, so intensity describes how much energy the sun deposits in an area every second.

The intensity of solar radiation falls off as the distance from the radiating object increases. Earth is 93 million miles from the Sun, so the intensity of solar radiation is much less at the Earth's surface than on the Sun. The intensity of solar radiation on Earth is 1370 watts per square meter. The ground does not receive this much energy, however, because of atmospheric absorption and reflection.