Red sky at morning

[2][3][4] The concept is over two thousand years old and is cited in the New Testament as established wisdom that prevailed among the Jews of the 1st century AD by Jesus in Matthew 16:2-3.

It is based on the reddish glow of the morning or evening sky, caused by trapped particles scattering the blue light from the sun in a stable air mass.

Conversely, in order to see "red sky" in the evening, high-pressure air mass from the west scatters the blue light in the atmospheric particles, leaving the orange-red glow.

There are occasions where a storm system might rain itself out before reaching the observer (who had seen the morning red sky).

The rhyme is generally correct at middle latitudes where, due to the rotation of the Earth, prevailing winds travel west to east.