the rate at which the sun's energy is received per unit area at the top of the earth's atmosphere when the sun is at its mean distance from the earth and atmospheric absorption has been corrected for. Its value is 1367 watts per square metre
solar constant in American English
the average amount of solar radiation received normally by a unit area just outside the earth's atmosphere, equal to c. 1.37 x 106 ergs per cm2 per second