Solar Radiation Reaching the earth Surface
Solar Radiation is received at the earth surface is in an attenuated (or) reduced because it depends on the mechanisms of absorption and scattering as it passes through the earth’s atmosphere,
Shows the solar radiation reaching the earth surface.
Absorption of solar radiations in the atmosphere are mainly due to presence of Ozone (O3), water vapor (H2O) and lesser due to other gases like carbon dioxide (CO2), Carbon Monoxide (CO), Oxygen (O2), Nitrogen (N2) and Other particulate matter,
Scattering of solar radiations in the atmosphere are mainly due to Air Molecules, gas Molecules as well as dust and water droplets. The scattered radiation is redistributed in all directions some going back into space and some reaching earth surface.
The x-rays and extreme ultra-violet (UV) radiations of the sun are absorbed by the Nitrogen, Oxygen, and other atmosphere gases
The atmosphere on the earth surface is classified into two types
i) Atmosphere without clouds
ii) Atmosphere without clouds
The mechanisms of absorption and scattering are similar as described above in both types of atmosphere. But the less attenuation takes place in a cloudless sky and hence maximum solar radiation is received on the earth surface.
Direct Radiation:
Solar radiation received at the earth surface without changes of direction (i.e., in line) with the sun is called Direct radiation (or) Beam.
Diffuse Radiation:
The radiation received at the earth surface from all parts of the sky’s hemisphere (after being subjected to scattering in the atmosphere) is called diffuse radiation.
Global Radiation:
It is sum of direct and diffuse radiation at the earth surface.
Several studies have been made on the mechanisms of Absorption and scattering for determination of attenuation coefficients for various substances but it is not possible to radiation at a specified on the earth surface.
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