Red sky at morning
The rhyme is a rule of thumb used for weather forecasting during the past two millennia. It is based on the reddish glow of the morning or evening sky, caused by haze or clouds related to storms in the region. If the morning skies are red, it is because clear skies over the horizon to the east permit the sun to light the undersides of moisture-bearing clouds. The saying assumes that more such clouds are coming in from the west. Conversely, in order to see red clouds in the evening, sunlight must have a clear path from the west, and therefore the prevailing westerly wind must be bringing clear skies.
There are occasions where a storm system might rain itself out before reaching the observer (who had seen the morning red sky). For ships at sea however, the wind and rough seas from an approaching storm system could still be a problem, even without rainfall.
Because of different prevailing wind patterns around the globe, the traditional rhyme is generally not correct at lower latitudes of both hemispheres, where prevailing winds are from east to west. The rhyme is generally correct at mid-latitudes where, due to the rotation of the Earth, prevailing winds travel west to east.
In the Bible at Matthew 16:2-3, Jesus is quoted as saying:
- When it is evening, you say, "It will be fair weather; for the sky is red."
- And in the morning, "It will be stormy today, for the sky is red and threatening."
- “Like a red morn that ever yet betokened,
- Wreck to the seaman, tempest to the field,
- Sorrow to the shepherds, woe unto the birds,
- Gusts and foul flaws to herdmen and to herds.”
The perils are foreshadowed using the archaic word "betokened"; some versions use the archaic term "Wrack" (for the word "Wreck").
There are other variations of the wording, including the following version using the plural word "sailors":
- Red sky at morning, sailors take warning;
- Red sky at night, sailors' delight.
Another version uses the word "shepherds":
- Red sky at night, shepherds' delight;
- Red sky in the morning, shepherds' warning.
- Kentucky Weather, by Jerry D. Hill, 2005, p.139, web: Books-Google-ikC
- "GuideLines - Buoy & Marker Messages", Paddling.net, 2009, webpage: PN-297
- "Weathervanes and Weather Wisdom. - Weather Station Channel", www.usedweatherstation.com, 2009, webpage: UsedWeath-6300
- The Complete Sea Kayaker's Handbook, Shelley Johnson, 2001, p.171, weblink: Books-Google-IC
- "Everyday Mysteries", Library of Congress, February 12, 2009, webpage: LOC-wsailor
- "Folk Lore Weather Forecasting", Cartage.org, 2008, webpage: Cartage-Lore
Media related to Sunrises at Wikimedia Commons
- This old saying actually has a scientific explanation National Oceanic & Atmospheric Administration (NOAA) Earth System Research Laboratory
- Everyday Mysteries, Library of Congress