Radiant flux density
Radiation flux density refers to the radiant energy received per unit area per unit time. Also called irradiated flux density. The symbol is E. It is usually expressed in Watts. It is a basic quantity in radiation climatology and radiometry. In the meteorological literature, it is often called radiant intensity, but the radiant intensity should be strictly speaking the radiant flux emitted by the unit solid angle of the source in a unit time.