Red Sky at Night

This was the sky looking west from my front porch last night. My husband spotted the shot. For better or worse, I took it. I’m sure many of you have heard the phrase “red sky at night sailors’ delight.” Here, according to the website: Everyday Mysteries: Fun Science Facts from the Library of Congress is why.

In order to understand why “Red sky at night, sailor’s delight. Red sky in morning, sailor’s warning” can predict the weather, we must understand more about weather and the colors in the sky.

Usually, weather moves from west to east, blown by the westerly trade winds. This means storm systems generally move in from the West.

The colors we see in the sky are due to the rays of sunlight being split into colors of the spectrum as they pass through the atmosphere and ricochet off the water vapor and particles in the atmosphere. 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.

During sunrise and sunset the sun is low in the sky, and it transmits light through the thickest part of the atmosphere. A red sky suggests an atmosphere loaded with dust and moisture particles. We see the red, because red wavelengths (the longest in the color spectrum) are breaking through the atmosphere. The shorter wavelengths, such as blue, are scattered and broken up.

Red sky at night, sailors delight.
When we see a red sky at night, this means that the setting sun is sending its light through a high concentration of dust particles. This usually indicates high pressure and stable air coming in from the west. Basically good weather will follow.

Red sky in morning, sailor’s warning.
A red sunrise reflects the dust particles of a system that has just passed from the west. This indicates that a storm system may be moving to the east. If the morning sky is a deep fiery red, it means a high water content in the atmosphere. So, rain is on its way.

About that weather report. It’s sunny now with chance of storm predicted for later in the day. It’s been a recent pattern. Hot, sultry days, then big storm, which sends the dog crouching into my lap at night.