lew (11/17/82)
The ratio of the difference in solar flux received by the northern and southern hemispheres, to the the total flux received by the earth is given by: sin( alpha ) * sin( phi ) alpha = inclination of polar axis (23.45 degrees) phi = orbital displacement of earth from vernal equinox This formula is easily derived when one realizes that the desired ratio is just the ratio of the area included by the equator's projection onto the plane of the terminator (twilight line), to the total area included by the terminator. The maximum value is about .4, meaning that at the summer solstice the northern hemisphere is receiving 70 percent of the solar flux to the southern hemisphere's 30 percent. This formula includes the effects due to the obliquity of the sun's rays and the variation of the length of the day. The path length of the sun's rays through the atmosphere shouldn't be a consideration, remembering that the air is warmed by any absorption. Of course, the reflectivity of the earth must be a function of the angle of incidence, as well as other things, so the formula only establishes a baseline. I derived this formula myself, so beware. Lew Mammel, Jr. ihuxr!lew