Can a red sky warn you of impending weather?

Published: Oct. 20, 2011 at 3:29 PM EDT
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By Andrew Freiden - email 

RICHMOND, VA (WWBT) - We've all heard "red sky at morning, sailor's warning — red sky at night, sailor's delight," but is there any truth to it? In a word, "yes!"

In order to make a red sky, you need to have clear skies. If there are no clouds, the sun is able to shine through a lot of the atmosphere before it gets to your eyes.

If the sun shines through a lot of dust or pollution, you'll see red.

So, how do you get a lot of dust and pollution in the atmosphere? A strong area of high pressure will do this — trapping those particles close to the ground.

When the morning sun rises in the east, producing a red sky, it means the stable high pressure system is moving to your east. It'll likely be replaced by clouds, rain, and maybe storms from the west. Thus: red skies at morning, take warning.

When the sun sets in the west, and red skies occur, it means that high pressure is approaching from the west. That typically means a day or two of pleasant weather. "Red skies at night, sailor's delight."

This rule doesn't always work — but it's way better than those sayings and superstitions about long term forecasts.  The groundhog for example? You'd do better guessing.