Sailors Take Warning, Red Sky At Night, Sailor’s Delight is how the rest of the saying goes. The ancient proverb began long before humans could predict the weather with any accuracy and we relied on observation to try to decipher what kind of day we would have.
The amounts of water vapor and dust particles in the atmosphere are good indicators of weather conditions. They also determine which colors we will see in the sky. We see the longer red wavelengths of light travelling through the thickest part of the atmosphere at sunrise and sunset, when the sun is low on the horizon, denoting an atmosphere loaded with dust and moisture.
Storms and rains usually move from west to east. A reddish sky around sunrise means a lot of water vapor already present in the atmosphere. As clouds come in from the west, rainy weather is thus expected. This explains why “Red sky in the morning, sailors take warning”.
A reddish sky near dusk means that weather has improved in the upstream area to the west. Sunlight scattered by the atmosphere is reflected by clouds, making the sky red. As the clouds overhead have moved eastward, the weather is expected to improve. That explains why “Red sky at night, sailors delight”.
When I got up this morning and saw this gorgeous sky I was exstatic, knowing we should be getting some rain here by tonight ;-) See more great photos at Skywatch Friday