Temperature rise of electrical apparatus as affected by radiation

Radiation is generally of importance only in apparatus cooled by natural convection and radiation. If such apparatus with a smooth exterior surface is mounted in the sun and shielded from the wind, an additional rise as high as 20 degrees centigrade may occur. White or gray nonmetallic paints may decrease solar effects. Fins and corrugations increase the ratio of convected to radiated heat and thereby decrease radiant effects.