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Jessi: hmmm... An alligator? A sock. That one looks like a rat! Have you ever looked up in the sky and seen shapes in the clouds? Clouds can be big and fluffy like a castle made of cotton candy or they can be thin and wispy like little white lines drawn on the sky, but have you ever wondered what the clouds are?

We know there aren't real alligators or socks up there, but what makes a cloud a cloud? Well, they might not look like it, but clouds are just big clumps of water droplets. But how did those water droplets get up there in the first place?

Water can exist in three different forms, a solid, a liquid or a gas. Ice is just a solid form of water, and water in your drinking glass is a liquid. And you can't see water when it's a gas which is called water vapor, but have you ever heated a pot of water and noticed that as it boils, the water level goes down?

The water that's not there any more has evaporated or turned into gas. It's become water vapor and floated up into the air. And that's basically how clouds are made. When the sun shines down on water in oceans, lakes and rivers, it acts in pretty much the same way as that pot on the stove.

It warms the water enough to turn a little bit of that liquid water into water vapor. Then, the water vapor rises into the sky and as it goes higher, the air gets colder. Finally ir cools down enough that it turns back into a liquid again, but this time it sticks to tiny bits of things floating around up there like dust, dirt, and smoke.

As more water vapor floats up and bumps into those sticky wet specks, the droplets get bigger and bigger until they're big enough to see. Now, they have formed clouds.

Even though all clouds are made of the same stuff, they can look pretty different. There are actually different kinds of clouds that scientists look for based on how they look and the type of weather that they produce.

So let's play cloud spotter again, but this time with science. First, we'll check out everyone's favorite, the cumulus cloud. We love these guys because they're the big puffy fluffy clouds that can make us think of alligators or socks or robotic rats. They're usually bright white and they're thick and dense enough that when one passes in front of the sun, it can cast a shadow. These clouds usually mean nice weather, but beware. When you start to see a cumulus cloud grow tall and turn dark grey, it can produce a big storm with lots of thunder, lightning and pouring rain.

Cirrus clouds are totally different. They're the super-thin wispy clouds high in the sky. If a cirrus cloud passes in front of the sun, you'll hardly notice, they're almost see-through. When you see these kinds of clouds in the sky, you're probably in for a nice sunny day.

Now, take a look at these stratus clouds. They form something that looks kind of like a blanket across a big chunk of the sky. They might look flat and smooth, or they might have a pattern that looks bumpy or wavy. Stratus clouds tend to block out a lot of the sun's light, so these clouds usually bring a grey, drizzly day.

But Cumulus, cirrus and stratus clouds are just the beginning. There are lots of different versions of these three main types, depending on how high in the sky the clouds form, and the shapes that they make.

You can be a cloud-spotter too! You have a chance to check out coll clouds every time you step outside. So keep looking up, and pretty soon you'll be a pro at telling your cirrus from your stratus. As for Squeaks and me, we're gonna get back to these cumulus clouds. I think that one looks like the giant squid.

Thanks for joining us on SciShow Kids! If you have a question or just something you'd like to learn more about, you can let us know by leaving a comment below or emailing us at kids@thescishow.com.

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