The Woodsman's Journal Online: Weather for Woodsmen...Red Sky at Night©

Wild weather at Sunset looking east, did you notice the faint red color? Photograph by the Author.

The first in a series of articles on weather for woodsmen and on weather proverbs and if they are true or false – Author’s Note

“...Red sunrise means a wet day...”

An example of weather-lore, attributed to E. B. Dunn, weather forecaster for the United Weather Bureau, New York City, 1902¹.

Centuries of weather watching have produced countless bits of weather-lore and weather proverbs, many of which rhyme as an aide to your memory, and these have been passed down through the centuries and even over millennia, in some cases! Now, some of these weather proverbs are nonsense and some even contradict themselves, but others can be of use in forecasting the weather over the next 24 hours, when you are beyond the reach of the TV weather forecasters. We are lucky, in this modern age, because we have meteorological science and research to tell us which of these proverbs are fake or true, and more importantly why they are true.

Using just one weather proverb to forecast the weather over the next 24 hours might lead to a false forecast, but as the Greek poet Aratus² wrote almost 2,300 years ago, “...make light of none of the [weather] warnings. It is a good rule to look for sign confirming sign. When two point in the same way, forecast with hope. When three point in the same way, forecast with confidence”.

Red sky at night,

Sailor’s delight.

Red sky at morning,

Sailors take warning.

“Red sky at night...”, is an old, old weather proverb that was known even during biblical times, since in the Bible, in Matthew 16:2, it says, “When evening comes, you say, ‘It will be fair weather, for the sky is red,’ and in the morning, ‘Today it will be stormy, for the sky is red and overcast”.

“But is this proverb true or false”, you ask? That’s a good question!

From “How Good Is Your Weather Eye?”, by Eric Sloane; in Popular Science, October 1944, pages 141 and 216.

It is true, but before we can tell you why it is true, we must talk a little about atmospheric convection currents, high- and low-pressure zones, the Coriolis effect, and prevailing winds³.

From and Introduction to Oceanography, by Paul Webb, HERE.

Prevailing winds are, according to the Oxford dictionary, “a wind from the direction that is predominant at a particular place or season”. It is always important when you travel or camp in the wilderness to know the prevailing wind direction, when canoeing it can help you stay in the calm water on the sheltered, lee side of the shore or if you put your camp on the windward shore, it can help blow the bugs away from your camp. It is also important to remember that prevailing winds are not constant all day long, as Alan Innes-Taylor noted on page 53, when he wrote of prevailing winds in the Arctic Survival Guide: “Fair weather winds usually decrease at night”.

The prevailing surface winds are created by atmospheric convection cells, powered by high- and low-pressure air. High pressure air is descending air that is cold and dry and generally brings clear skies. Low pressure air is raising warm air that is moisture laden, saturated and generally brings precipitation. The Coriolis Effect also plays a part in creating the prevailing winds because, in the Northern Hemisphere it deflects the winds to the right and in the Southern Hemisphere to the left.

Prevailing winds are named for the direction that they are blowing from, not from where they are blowing to. And since there are three convection cells in each hemisphere, there are six sets of prevailing winds. So, between the poles and 60^o latitude, in both the North and South Hemispheres, the prevailing winds blow from the east and are called the “polar easterlies”. In the belt between 60^o and 30^o latitude in both hemispheres, the “westerlies” are the prevailing winds and blow from the west. And between 30^o latitude and the equator, in the Northern Hemisphere, the prevailing winds blow from the northeast and are called the “northeast trade winds”; while in the Southern Hemisphere the prevailing winds blow from the southeast and are called the “southeast trades winds”.

So, why is it true?

An excerpt from “Red Sky At Night...”, by Donald Johnson and Jean Smith, in Cruising World, July 1995.

The weather proverb, “Red sky at night...”, was developed in Europe and it will hold true throughout the temperate latitudes of both the Southern and Northern Hemisphere, which includes all of Europe, Central Asia, and North America below the arctic.

The best explanation I have ever found for why this proverb is true, is from “Red Sky At Night...”, by Donald Johnson and Jean Smith, in Cruising World, July 1995⁴. They explained that because the prevailing winds, within the temperate latitudes between 30^o and 60^o north or south latitudes, blow from west to east, by looking at a sunset you are getting a preview of tomorrow’s weather.

If you see a red sky at night, then that means that the setting Sun is reflecting off the backs of clouds to the east of you and the dust in the atmosphere is scattering all but the red light in the Sun’s rays, painting the sky red. Since the clouds are to the east of you and the air is clear to the west of you then tomorrow should dawn fair and clear, with no rain. However, if you see a pale, gray sunset at night, then that means that the Sun’s rays are shining through water droplets in the air that will reach you by tomorrow and you will have rain!

If you see a red sky at morning, then that means that the Sun’s rays are bouncing off the front of approaching cirrus clouds which are to the west of you, and all but the red light is being scattered, leaving a red sky as a warning of oncoming bad weather!

An excerpt from Almanac and Weather Forecaster, by Eric Sloane, page 98.

Additionally, rainbows can help you forecast the weather just as a sunset can. If you wake up in the morning, as the sun rises in the east, and you look west and see a rainbow, it means a storm is approaching you from the west. However, at night, as the sun sets in the west, if you see a rainbow to the east, it means that the storms are moving away from you to the east.

From “How Good Is Your Weather Eye?”, by Eric Sloane; in Popular Science, October 1944, pages 141.

So, now that you know the reason why the “Red sky at night...” weather proverb is true you will be able to answer the questions above correctly. To check yourself, see the answers below.

From “How Good Is Your Weather Eye?”, by Eric Sloane; in Popular Science, October 1944, pages 216.

So next time you see that beautiful red sky at sunset, don’t think romantic thoughts, think high-and low-pressure systems, prevailing winds, and tomorrow’s weather forecast!

Don’t forget to come back next week and read “Maple Syrup Making ©”, where we will talk about sap, trees running and how to make maple syrup.

I hope that you continue to enjoy The Woodsman’s Journal Online and look for me on YouTube at BandanaMan Productions for other related videos, HERE. Don’t forget to follow me on both The Woodsman’s Journal Online, HERE, and subscribe to BandanaMan Productions on YouTube. If you have questions, as always, feel free to leave a comment on either site. I announce new articles on Facebook at Eric Reynolds, on Instagram at bandanamanaproductions, and on VK at Eric Reynolds, so watch for me.

That is all for now, and as always, until next time, Happy Trails!

Notes

¹ From American Boys’ Book Of Signs, Signals and Symbols, by Dan Beard, page 183.

² Aratus was a Greek poet who lived circa 215 to 345 BCE.

³ Once about eight years ago, while watching the Sun setting over a lake in Canada, I tried to explain the “Red sky at night” proverb to another wilderness guide and I made a complete hash of it, because I didn’t fully understand and obviously couldn't explain atmospheric convection currents, the Coriolis effect, prevailing winds, and high- and low-pressure zones. Lesson learned!

⁴ The entire excerpt of “Red Sky At Night...”, by Donald Johnson and Jean Smith, talking about why this proverb is true is below for your convenience