On Tue, Dec 11, 2007 at 12:06:22PM -0800, shadow at shadowgard.com wrote: > Nope. You forget that heating depends on both heating from the light > passing thru the air but also heating due to the way the surface > under the air heats up (which is mostly due to albedo) True. If there are large-scale variations in average albedo, that would do it. - Tim