(WKBN) — Everyone has heard the phrase “Red sky at night, sailor’s delight. Red sky in morning, sailor’s warning.” In fact, it is probably one of the most common weather phrases that is tossed around.
One of the reasons for this is the fact that sunrises and sunsets are often beautiful and they catch the eye. The second reason is that the phrase rhymes.
However, is there any truth to the popular phrase? And, why is the sky a different color in the morning and evening? Well, time to get your sea legs as we sail through the science of red skies!
Why is the sky a different color than blue?
You probably learned at an early age that the sky is blue during the daytime, but why is there color in the sky at all? And, why does it sometimes change color? Part of the answer to this question is the human eye.
Our eyes can be referred to as “passive sensors” which means that it takes in light from the sun in order to determine the color, shape and size of objects. This is different from an “active sensor” like a weather radar which actually transmits energy to determine the location and intensity of precipitation.
The sun emits energy of many different frequencies which is called the electromagnetic spectrum. One example is ultraviolet rays. These rays are not visible to the human eye, but they are responsible for the sunburn you get during the summertime. The human eye can only see a small part of the energy that is emitted from the sun. This is called the visible spectrum.
The visible spectrum includes the colors red, orange, yellow, green, blue, indigo and violet or (ROYGBIV). The colors listed above are listed in descending order in regard to wavelength.
When light enters Earth’s atmosphere, the gases that make up the atmosphere scatter and even absorb the incoming energy. The gas ozone protects humans from harmful UV rays that would otherwise cause harmful effects on our bodies.
The atmosphere also scatters light in the visible spectrum. During the day, the light incoming to the atmosphere is scattered more at shorter wavelengths (violet, indigo and blue). Therefore, to the human eye, the sky appears blue because that is the part of the visible spectrum that is being scattered.
However, during the morning and evening hours, the incoming light has to travel through more atmosphere. This causes the shorter wavelengths to be scattered before the sunlight reaches the surfaces which leaves only the red and orange colors for the eye to visualize.
Therefore, part of the reason for red skies has to do with the Earth’s atmosphere but what about clouds?
Red sky at night sailor’s delight
The general idea for this part of the phrase is that if there is a red sky as the sun is setting, then there are generally fair weather clouds overheard. If there were thunderstorms, for example, then it would not be likely to see the red sunset.
This of course would not always be accurate, a storm system that was not on the horizon could move over the area later that night. However, a red sky can definitely mean that a period of nice weather is ahead.
Red sky in the morning sailors take warning
The idea for this part of the phrase deals with the fact that weather patterns usually move from west to east in the mid-latitudes. Therefore, if there are red skies in the morning then there are clouds drifting in from the west which could mean that a storm is on the way.
Once again, there are many exceptions to this rule. Like today, for example! Meteorologist Adam Clayton took this picture this morning of the sunrise which features pink and red colors. However, the weather today is going to be fantastic today with partly cloudy skies and highs in the low 70s.
Now, the next time someone brings the phrase up you can educate them on the science!