Rainbow: Caused by the reflection and refraction of the rays of the sun shining
on falling rain. It was appointed as a witness of the divine
faithfulness
(Genesis 9:12-17) It existed indeed before, but it was then
constituted as a sign of the covenant. Others, however (as Delitzsch,
Commentary on Pentateuch), think that it "appeared then for the first
time in the vault and clouds of heaven." It is argued by those
holding this opinion that the atmosphere was differently constituted
before the Flood. It is referred to three other times in Scripture
(Ezekiel 1:27,28; Revelation 4:1-3; 10:1)