A Rainbow

After all the rain we finally got a rainbow and some sunshine. This rainbow was visible across the whole eastern sky except for some cloudy interruptions. Although the grasses look rather brown in the photo, they are actually quite green and lush. Perhaps it is the sun shining on the seed heads of the grasses that produce the look.

Lex never tires of telling me about rainbows - he used to build multiple scattering computer models for remote sensing studies of clouds. René Descartes (in 1637) was perhaps the first to give a satisfactory explanation of how rain and sunlight produce the rainbow. How the primary rainbow results from rays of direct sunlight that pass into the raindrop, are reflected once inside, and pass back out in a direction 42 degrees from the anti-sun point. Then there's Keats, who, in his poem Lamia, reacted to this kind of understanding:

   There was an awful rainbow once in heaven:
   We know her woof, her texture; she is given
   In the dull catalogue of common things.
   Philosophy will clip an Angel's wings,
   Conquer all mysteries by rule and line,
   Empty the haunted air, and gnomed mine -