How much do you know about the fall equinox? WLTX Meteorologist Alex Calamia drops some weather facts about the season.
Did You Know...
Fall equinox means equal nights, so the days and the nights should be equal. However, looking at the sunrise and sunset times for September 23, 2019 in any city of your choice across the world, turns out it’s not 12 hours. 7:12 a.m. was the sunrise. 7:19 p.m. was the sunset, and that’s not a 12-hour day. That’s a 12-hour and 7-minute day. It's definitely not equal.
So, what’s going on? Well, it’s not that you don’t know about fall. What’s tricking you is what you know about sunrise and sunset times.
Let’s take a look at the meaning of a sunrise and sunset. Now, a sunrise or a sunset is actually when the top of the sun’s disk appears either over the horizon for a sunrise or under the horizon for a sunset. It’s not the center of the sun that is the exact definition of a sunrise or sunset, so that gives you a little extra daylight length as well.
Another interesting cause is the way that the sun’s rays travel in space. There is no air in space. There is no density in space, so light just moves straight. However, when it hits the Earth’s atmosphere, it actually curves a little bit. That’s called refraction. The light bends, so the sun appears higher in the sky than it actually is.
If that explanation just totally blows your mind and doesn’t make sense, here's a comparison to explain the phenomenon. You probably drink water in glass or a mug. Then, if put a spoon or straw in it, you'll notice something kind of interesting. Do you see how the spoon almost looks like its detached from itself? It's the same principle that goes on with our sun’s rays when they enter the atmosphere on the Earth. Because water is denser than air, your eyes are tricking you.
That same principle is what happens with the light bending when it hits that denser atmosphere. Our Earth’s atmosphere is like that mug of water or cup of water. It bends the light, so things aren’t as they appear, and it kind of tricks our eyes a little bit. That’s what happens when there is this longer amount of day light on the first day of fall then what you might actually expect.
Alex Calamia is a morning meteorologist at WLTX in Columbia, SC. You can watch his forecasts every weekday. Learn more about Calamia and how he got interested in weather by clicking here.