Radiation Balance Or Net Radiation
The net radiation is the difference between the total downward and upward radiation fluxes and is a measure of the energy available at the ground surface. The balance of energy after gain and loss of both short wave and long wave radiation fluxes is known as net radiation.
Net radiation represents the amount of energy, which is used for various kinds of activities. It is dispensed as sensible heat, latent heat and also in physiological processes such as photosynthesis and respiration.
The importance of this parameter is that it is the fundamental quantity of energy available at the earth’s surface to drive he processes of evaporation, air and soil heat fluxes as well as other smaller energy consuming processes like photosynthesis etc.
If we consider the extra terrestrial radiation reaching annually (338wm-2)as 100%; Then out of this-
The net radiation reaching (SW) =100-28+25)-47% the earth surface. =114%
Long wave radiation reaching at earth surface =+96%
Therefore, Net long wave radiation =-114+96 = -18%
Net all wave radiation at earth surface =+47-18 = 29%
This surplus energy is used at the earth surface for
a) Sensible heat (QH) =4%
b) Latent heat (Eva)(QE)=25%