the fraction of the total radiation that is reflected by any surface is called its
The fraction of the total solar radiant energy reflected back to space from clouds, scattering and reflection from the Earthâs surface is called the albedo of the Earth-atmosphere system and is roughly 0.3 for the Earth as a whole.igure 2.1: The Sun's rays incident on the Earth. I0 = irradiance on a plane perpendicular to the Sun's rays. The solar constant (I SC) is the average radiation intensity falling on an imaginary surface, perpendicular to the Sunâs rays and at the edge of the Earthâs atmosphere (figure 2.1).