Disclosed is a net radiometer that measures the net difference between incoming solar and outgoing terrestrial radiant flux energy in the combined short-wave and long-wave far infrared spectral range. In accordance with principles of the invention, a balanced net radiometer can be constructed where each thermal absorber is formed from two separate pieces joined together to form a single thermal mass. Within each thermal absorber, each piece is coated with a separate surface coating of different spectral sensitivity. By constructing an absorber from two separate pieces, it is possible to apply spectral coatings with different curing characteristics, to thermal absorber that acts as a single thermal mass. The pieces within each thermal absorber are sized in a proportion that thermally balances the absorber's thermal sensitivity between short-wave and long-wave far infrared radiant energy.