Diffuse and direct beam solar radiation, From: K.A. Lemke, University of Wisconsin-Stevens Point
Diffuse and direct beam solar radiation, From: K.A. Lemke, University of Wisconsin-Stevens Point

Diffuse and direct beam solar radiation

The solar radiation reaching the Earth's surface can be divided into two types of solar radiation: Direct beam solar radiation and diffuse solar radiation

 

As sunlight passes through the atmosphere, some of it enters the surface of the Earth direct and undisturbed - the so called beam solar radiation. Beam solar radiation throws sharp shadows and can be focused.

Another component of sunlight is the diffuse solar radiation. On it's way through the atmosphere it is absorbed, scattered, or reflected by:

 

    • Dust
    • Water vapor
    • Clouds
    • Pollutants

 

Diffuse solar radiation does not throw sharp shadows and cannot be focused.

The sum of the diffuse and direct beam solar radiation is called global solar radiation.

global solar radiation map worldwide 1981-2001
global solar radiation map worldwide 1981-2001 Source : Meteonorm 2008


direct beam solar radiation map worldwide average 1981-2000
direct beam solar radiation map worldwide average 1981-2000 Source : Meteonorm 2008