Bill Burton: It's time for us to take a look at the Science Behind the Forecast as we're joined by WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.
Tawana Andrew: Good morning. And today we're kind of answering a question that one of my coworkers had, which I thought was was pretty interesting about how we basically start our day.
BB: Yeah, in-house questions can always be great. And the question was to ask about sunrise. So that's our topic today. We're talking about sunrise. What do we need to know?
TA: Well, overall, the question was just about sunrises, and how I know when I'm on TV, just looking at something that a sunrise is going to be gorgeous well before it even happens. And things that I think about is just overall how our atmosphere works.
We have majority oxygen and nitrogen as the main components in our atmosphere, and when sunlight hits those molecules, that light is scattered all over our atmosphere depending on the wavelength of light. So overall, since you have oxygen and nitrogen, which are pretty small overall compared to the wavelengths of light, they tend to scatter more of that blue and the purple. But because of the way our eyes work, we mainly just see the blue light, and our sky is blue because of what's called Rayleigh scattering, and that is fully dependent on wavelength. So when the sun is directly overhead, that light scattering is at its maximum, and we see that bright blue color. Now at sunrise, at sunset, when you see the sun getting a little bit further down and horizon, the wavelength of visible light increases a little bit more, and that is why you see more of those oranges. You see more of the red in that situation.
Now there's an idea that pollution and even extra moisture in the air can make sunrises and sunsets look brighter, but it's actually the opposite effect. It makes it more muddy, and mutes the colors a little bit more of the sunrise, because these particles are basically absorbing more light and scattering all the wavelengths equally. So you don't see those distinct colors like you like to see in a gorgeous sunrise. And in fact, you see brighter sunsets in the eastern half of the country in fall and winter, because we don't have as much moisture in the air at that point, we don't have as much of the pollutants. So the air is cleaner, it's drier, and the sun just has a clear path straight across the sky, and that's why those fall and winter sunrises and sunsets just seem to be more crisp, if you want to put it that way.
And clouds, in my opinion, make things even better for a sunrise and sunset. The clouds tend to just grab that little first piece of light that comes over the horizon at sunrise and reflects it down towards the ground, so you end up having the more colorful, more interesting sunrises and sunsets when you have mid to upper level clouds, like altocumulus and cirrus clouds, because it's just reflecting the light in a slightly different way and making things, in my opinion, especially, a little bit more interesting.
So if you ever hear me on TV in the morning saying, "Oh, we have upper level clouds coming in, and there's low humidity," grab your phone, grab your camera, because you know it's going to be a really good sunrise on that day.
BB: Noted. And now we have a much better understanding of how a sunrise is going to look good and what we need to look for that really cool sunrise. Thanks to the latest edition of Science Behind the Forecast with WAVE 3 meteorologist Tawana Andrew. Thanks for the knowledge, Tawana.
TA: Of course.
This transcript was edited for clarity.
