If you’ve ever watched the clouds in the sky, you know how different they can look from day to day. When they’re fluffy like cotton or thin and wispy and white, it can be hard to remember that that’s actually ice and water floating above your head. How come it doesn’t fall?
Well, it eventually does. When water vapor rises from the ground, it rises as incredibly tiny droplets of water, and some form tiny ice crystals. When enough of those tiny pieces come together, they form a cloud. We’re talking about millions of droplets here, but they’re so tiny and light that they can float on the wind. If more and more droplets get pushed together, though, they eventually get so heavy that they can’t float anymore, and fall to earth as rain. Like us, clouds can’t fight gravity forever.
Wee ones (counting on fingers): If you count 2 fluffy clouds floating over your front yard and 7 clouds floating over your backyard, how many clouds do you see?
Little kids: Different kinds of clouds form at different heights above us. Cirrus clouds, the thin wispy horse-tail ones, start about 19,000 feet above the ground. Heavy cumulonimbus clouds – the ones with thunder and rain – have a base just 6,000 feet up at most. How much higher do the wispy cirrus clouds start? Bonus: Clouds travel at different wind speeds, too: those sluggish thunderclouds move around 30 miles an hour, while the cirrus clouds can be pushed at up to 100 miles an hour. At those speeds, how much faster are the cirrus clouds?
Big kids: Rain can fall anywhere from 7 to 18 miles per hour. If it’s falling just 10 miles per hour, and the rainclouds are just 1 mile up from the ground, how long does it take the rain to fall from the cloud to you? (Remember: there are 60 minutes in an hour). Bonus: What if the rain is falling at 12 miles an hour – now how fast does the rain reach you?
Wee ones: 9 clouds.
Little kids: 13,000 feet higher. Bonus: 70 miles an hour faster.
Big kids: 6 minutes. Bonus: 5 minutes.