Do different parts of the world receive different amounts of sunshine during the year? Ignore clouds, or consider only what is received either on the cloud tops or surface, whichever is available. Is it the same at the poles as at the equator? ... the northern and the southern hemispheres?
Consider two interpretations of the above: (1) number of hours per year that the sun is up, (2) the total insolation (total solar energy received per unit of area of the ground) received during the year, weaker when the sun is low near the horizon than when it is high in the sky.
(In reply to
re(2): Unscientific solution by Bryan)
I suppose I wasn't clear. Pick a spot way up North OR way down South. At that (one) spot, the length of total darkness is greater than the length of total light. My personal example is that I have my old University roommate, who lives in Innuvik, NWT, at approximately lattitude 69 degrees. In the summer, the sun stays up 24 hours per day for about 3 weeks, while in his winter, it stays dark 24 hours per day for much longer than 3 weeks.
I know that from a total perspective, half of the earth is lighted up (or very close to that) at a time, so that discrepancy must be made up somewhere. Since I've never been south of California, I guessed that the tropic area would accomodate this, because, of course, the two pole areas must be closely symmetric.
Or I may be wrong, because if I lived where it was always cold and dark, I might be depressed enough about it to exaggerate as well...
re(3): Unscientific solution
