Tuesday, June 24, 2008

Rainbow over DC...

photo Martin-Lane Cochran

Epicurus (341–270 B.C.) writes in his letter to Pythocles:
The rainbow arises when the sun shines upon humid air; or again by a certain peculiar blending of light with air, which will cause either all the distinctive qualities of these colors or else some of them belonging to a single kind, and from the reflection of this light the air all around will be colored as we see it to be, as the sun shines upon its parts. The circular shape which it assumes is due to the fact that the distance of every point is perceived by our sight to be equal; or it may be because, the atoms in the air or in the clouds and deriving from the sun having been thus united, the aggregate of them presents a sort of roundness

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