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Fun folklore...fact or fiction?

Science with Stevie: An old weather saying...

WMAR

By: Stevie Daniels

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I'm sure most of you have heard that old saying, "Red sky at night, sailors delight" and "Red sky at morning, sailors take warning". This concept was used by sailors to forecast the weather in order to navigate ships. This saying is cited in the Old Testament and is over 2,000 years old! In Matthew 16:2-3, Jesus says, “When it is evening you say, ‘It will be fair weather, for the sky is red’; 3 and in the morning, ‘It will be foul weather today, for the sky is red and threatening.’"

Some of you may wonder if this folklore concept is accurate.. I am here to say that it is mostly true in the mid-latitudes as weather systems normally move from west to east. Let me explain...

Here is the science behind why we see beautiful bright red, orange, and yellow colors in the sky during sunrises and sunsets:
There are molecules and small particles suspended in the atmosphere. When the light from the sun hits these atoms, light waves scatter in all directions. Sunlight produces a spectrum of colors: red, orange, yellow, blue, and violet hues...and they travel at different paths. Blue light waves travel on a short route (short waves), whereas red, orange, and even yellow light waves take a longer route (long waves). During sunrise and sunset, the sun is at a lower angle in the sky. Therefore, the sunlight has a longer route to travel through the atmosphere to reach our eyes! The short blue wavelengths get kicked out, due to the atmosphere favoring longer wavelengths, like red, orange, and yellow. This is why red, orange, and yellow light become more visible to us...creating spectacular views at dawn and dusk.

"Red sky at morning, sailors take warning" can mean high pressure has already passed to the east, allowing for a low pressure system to move in from the west. High water content in the atmosphere off to the west will make the sky appear red as the sun rises in the east. This signifies that rain and high winds are on the way.

"Red sky at night, sailors delight" indicates high pressure (fair weather) is heading eastward. When the sun sets in the west, it transports light through a large cluster of particles and aerosols eastward. This means that a low pressure storm system is likely moving away from the area and a high pressure system is approaching. This means stable/sinking air is arriving from the west—meaning good weather is on the way!