This parameter is of special interest in agricultural meteorology. - The duration of sunshine (units hr per day) allows for estimates of the energy available for physical and bio- logical processes For accurate investigations, measurements of the different radiation (solar and terrestrial) fluxes are required. In meteorology, the following radiation fluxes are measured - Solar radiation fluxes (shortwave length 0.29 - u) . Direct solar radiation is measured at normal incidence. . Global solar radiation downward direct and diffuse solar radiation received on a horizontal surface from a solid angle of 2 PI. . Sky radiation downward diffuse solar radiation received on a horizontal surface. . Reflected global radiation Solar and diffuse radiation reflected by the surface (bare or covered by vegetation)
