The difference between the absorbed solar radiation and the net infrared radiation. Experimental data show that radiation from the earth's natural surfaces is rather close to the radiation from a black body at the corresponding temperature; the ratio of the observed values of radiation to black body radiation is generally 0.90-1.0.

the Earths energy balance between the incoming solar energy and outgoing energy radiated out as longwave radiation

The resultant flux of the solar and terrestrial radiation through a horizontal surface. It is considered positive in the flux downwards exceeds that upwards. It is also termed 'net radiation'.

Algebraic sum of all the radiant heat inputs and losses at a surface (e.g., a snow surface).