The common phrase "Red sky at morning" is a line from an ancient rhyme

Rhyme

A rhyme is a repetition of similar sounds in two or more words and is most often used in poetry and songs. The word "rhyme" may also refer to a short poem, such as a rhyming couplet or other brief rhyming poem such as nursery rhymes.-Etymology:...

 often repeated by mariners or seamen, during the past centuries:

Red sky at night, sailor's delight.

Red sky at morning, sailor take warning;

There are other variations of the wording (see below: Other versions). The rhyme is a rule of thumb

Rule of thumb

A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...

 for weather forecasting

Weather forecasting

Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Human beings have attempted to predict the weather informally for millennia, and formally since the nineteenth century...

, dating back over 2,000 years, based on the reddish glow of the morning or evening sky, caused by haze or clouds related to storms in the region. Due to the rotation of the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, from west to east, storm systems tend to travel eastward across a local region of the globe.
A reddish sunrise

Sunrise

Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...

, caused by particles suspended in the air, often foreshadows an approaching storm

Thunderstorm

A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

, which will be arriving from the west, within the day. Conversely, a reddish sunset

Sunset

Sunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.The time of sunset is defined in astronomy as the moment the trailing edge of the Sun's disk disappears below the horizon in the west...

 often indicates that a storm system is on the east side (opposite the sunset), travelling away from the viewer. A similar movement is noted all around the world, in both the northern and southern hemisphere

Southern Hemisphere

The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

.

There are occasions where a storm system might rain itself out before reaching the observer (who had seen the morning red sky). However, for ships at sea, the wind and rough seas, from an approaching storm system, could still be a problem, even without rainfall.

History

A similar adage appears in a poem by William Shakespeare

William Shakespeare

William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

. He said something similar in his Venus and Adonis

Venus and Adonis

Venus and Adonis, a classical myth, was a common subject for art during the Renaissance and Baroque eras. Some works which have been titled Venus and Adonis are:-Literary works:...

(1593):

“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").

In the Bible (Matthew XVI: 2-3), Jesus is quoted, "When in evening, ye say, it will be fair weather: For the sky is red. And in the morning, it will be foul weather today; for the sky is red and lowering."

Other versions

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 morning, shepherds' warning.

A storm system can approach from the west, either on land or at sea.

External links

• Everyday Mysteries, Library of Congress