By Tom Brown
A real rainbow, one in the sky, comes together with rain after an afternoon shower. Usually fragments only pieces between patches cloud can be seen going into open and then behind the clouds. You don't see them very often.
After a storm the rain mist and suspended water droplets reflect sunlight so that the sun must always be from behind. Such the rainbow is seen in the east in the late afternoon and before sunset. The rain is in the east of course and sunlight comes through below cloud from the west.
These observations may be easily explained with a basic understanding of relevant principles of the optics and geometry involved.
Theoretically I would say that a rainbow might also be seen in the west with sunrise and rain under the right conditions because you have a symmetric situation. Although I can't remember ever seeing one like this I can imagine it would be especially beautiful since the sky would be fresh and clean.
Very rarely too I have seen what I call a dirty red rainbow it looks ominous, terrible. I do not know what it is but the sky looks dirty, the air dark with smoke and dust the sky filthy brown reddish.
Occasionally a rainbow has company. A secondary rainbow which is not so often seen it is above and fainter, the bands are vague and broader with the colours less intense. In this second one the order now is inverted, the sequence of colours is reversed.
Even from the very earliest times and still today the appearing and the beauty of a rainbow has been a symbol of hope and happiness, believed to be a sign of God's great mercy and vow of forgiveness, a promise of peace and blessing of the earth and life.