A. Because that air alone contiguous to the earth is damp and full of vapour. There are no vapours in the higher regions of the air to reflect red rays; and hence the morning-light looks grey.
Q. What difference (in the state of the air) is required, to make a grey and red sunrise?
A. In a grey sunrise, only that portion of air contiguous to the earth is filled with vapour; all the rest is clear and dry. But in a red sunrise the air in the upper regions is so full of vapour that the rising sun cannot disperse it.
Q. Why is a grey sunset an indication of wet?
A. If the air on the surface of the earth be very damp at sunset, it is a proof that the air is saturated with vapour, and wet may be expected: hence the proverb—
“Evening red and morning grey
Will set the traveller on his way;
But evening grey and morning red
Will bring down rain upon his head.”
Q. The proverb says, “A rainbow in the morning is the shepherd’s warning:” why is it so?