This edition of Science Behind the Forecast originally aired in March, 2023.
Bill Burton: It is time for us to take a look at the Science Behind the Forecast as I am joined by WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.
Tawana Andrew: Good morning. I feel like I'm about to terrify and inspire a lot of people with today's topic.
BB: I think terrify and inspire are the two best words to sum this up. And we're gonna talk about something that I'm not sure I know - I never thought of, and I don't know how many others have. The weight of clouds.
TA: Yes, so we look at them and you're, we usually think, oh, they're so light and fluffy and they can't weigh that much, right?
BB: Well, course not, they're like cotton candy.
TA: Yeah, exactly. Yeah, it is clouds can actually be pretty heavy and you have to consider first that air is not weightless. So you have air pressure or barometric pressure, and at sea level, that's around 14.5 pounds per square inch. So just even the air around us is actually pushing down on us. And then you have the clouds that are made up of these Itty bitty tiny water droplets and for a cumulus cloud, the water density has been estimated to be near about 0.5 g of water per cubic meter. So those cumulus clouds are those puffy clouds that kind of look like cotton candy on a summer day. That's what we're talking about right now. And 1 cubic kilometer cloud contains a billion cubic meters. So if we do the calculations, which, you know, it's early in the morning and I know that's difficult, but we can do it.
BB: I'm going to leave that to the professional meteorologist.
TA: We find out with those calculations that there are 500 million g of water droplets in one cubic meter cloud. So that translates to 500,000 kg or 1.1 million pounds. That is 1 cubic kilometer cumulus cloud, 1.1 million pounds.
BB: And that's hanging over our heads at any given moment.
TA: Exactly. And to put that into context for you.
BB: Yes, please.
TA: That's around 5 times as heavy as a blue whale, which is the largest animal on our planet.
BB: Wait, 5 times as heavy as a blue whale.
TA: Yes.
BB: OK, I'm going to be frightened to go outside. My umbrella is going to seem very inadequate.
TA: Sunny day, keep in mind.
BB: A sunny day...oh!
TA: We're not even talking about cumulonimbus clouds, those thunderstorm clouds. No, no, no, we're talking about a normal cumulus cloud here. So...you put that into context.
BB: I'm going to have to look up what the word is for fear of summer and summer clouds.
TA: Hopefully, no one is scared. You'll be fine. The reason that we will all be fine and the reason why all of that weight isn't just, you know, collapsing down on us is the fact that the weight isn't concentrated in one area. It's actually spread out over a large space. Also water droplets can be so small that gravity barely affects them. And clouds are less dense than dry air, so that buoyancy helps to keep them afloat. Eventually, of course, once a cloud's water density does increase to a certain point and the droplets get larger and heavier, the cloud will eventually fall as rain. But until that point, Yeah, they're gonna stay over our heads and we will be just fine, but yes, one normal cumulus cloud can be 1.1 million pounds. Let that torture you for the rest of your day.
BB: That is most definitely a lot to absorb. And Tawana, I have to apologize for this up front, but I need to say this. Tawana, that's heavy.
TA: Oh, that, that's good.
BB: But at least now we have an understanding when we look at those lovely summer clouds that there's a lot of weight up there and it's amazing how it actually stays in place, but now we have a better understanding of it thanks to Science Behind the Forecast with WAVE 3 meteorologist Tawana Andrew. Thanks for the knowledge, Tawana.
TA: Of course.
This transcript was edited for clarity.
