These are cumulus clouds — when you're outside on a bright, sunny day, you might

see hundreds of them. Like all clouds, they're formed when water vapor in our atmosphere

sticks to tiny particles of dust and salt and pollution floating around in the sky — called

aerosols. When the vapor hits an aerosol, it transforms into water droplets or ice crystals.

And when enough of those come together, they form clouds. Every cloud is packed with

information — and knowing a bit about them can help you tell the difference

between a cloud that'll disappear in a few minutes...and one that could ruin your picnic.

To really know what's going on in a cloud, you have to go right inside it.

That's what atmospheric scientists do!

I use satellite data, aircraft data, and even sometimes weather balloon data to understand

these processes associated with clouds and precipitations.

That's Dr. Mayra Oyola, she's an atmospheric scientist who works at NASA's jet propulsion

lab. She's also very good at identifying clouds — like those cumulus ones.

Cumulus means “heap” in Latin, and you can kind of see why — they look like big heaps of

cotton. I saw a bunch when I was on a bike ride in August.

These clouds are normally present when we have fair weather or good weather. So it's

a good day to go outside and play. Cumulus are one of the 10 most common cloud types,

which scientists started defining all the way back in 1802: There's also Stratus,

which means “layer.” They cover the sky like a blanket.

They vary in color. So you can see some that are whiter but they can be grayish – they

are normally associated with what we call fair weather. Our friend Anna in Michigan

saw some of those: “The weather today is nice and warm.” Cirrus, which means

curl, look like wisps of hair high in the sky. My coworker Agnes found these above Lake

Michigan in Chicago.

Cirrus clouds, because they're so high, they're very cold. They're mostly ice, very tiny particles

of ice, and they're short-lived. And there's Nimbus, which means rain.

They're normally seen during a thunderstorm, along thunder and lightning.

These four basic cloud shapes — combined with how high they are in the sky — create

the most common clouds. Like this cirrostratus clouds — which exist

above 7,000 meters.

They're kind of like thin sheets that spread across the sky. These clouds are interesting

because they tend to be useful to do weather forecasting in the sense that they can tell

you if there's precipitation or snow storm coming within 12 to 24 hours.

Altostratus and altocumulus clouds hover a bit lower, between 2,000 and 7,000 meters.

They often form a sheet — like these fluffy altocumulus ones Vox producer Laura saw in

Maine. If you see them in the morning, this is a tip for weather forecasting. What it

means is that you need to be prepared because they're normally produce ahead of thunderstorms.

Altostratus are less puffy, and more like one big blanket.

They normally thicken into being more type of rain bearing clouds like nimbostratus.

If you see a low, dark gray blanket of clouds, you're probably looking at nimbostratus

— and it's probably already raining, like it was in my backyard the other day.

Really coming down out here.

Rain often comes from cumulonimbus clouds, too — they tower from close to the ground

to really high in the sky.

They're not gonna be your classical white puffy clouds. They're probably gonna be darker

and grayish. So they're very distinct and very easy to identify.

When you look at this chart, it seems pretty simple to tell the difference between these clouds.

But in reality, it can get a little tricky. For example — look at this photo my friend

Jess took while canoeing.

These are definitely cumulus and cirrus clouds. We know that cumulus are associated with fair

weather – However, in this particular case, I can probably tell that there was a storm

before the picture was taken.

For the most part, storms tend to expand all over the atmosphere. So you have impacts of

the storm really high up in cirrus clouds, tend to be really high up in the atmosphere.

During sunrise or sunset, it's pretty common to see a colorful mix of clouds in the sky.

It's very specific in the sunset because you obviously have a very sharp change in temperature

going on at the time.

Those 10 clouds we just talked about make up nearly all the clouds in the world.

But what about the ones that don't fit on this chart?

Like here, on top of Mount Fuji in Japan.

Mountain ranges and other high obstructions disrupt the normal flow of air.

As air moves over the mountains, sinking air warms and rising air cools — which creates

these lenticular clouds. They look like fluffy UFOs.

Extreme weather can bring unusual clouds all over the world. Imagine you're sitting outside

and you start to see these bumpy, baggy clouds roll in: They're called mammatus clouds

— and they usually come along with thunder, lightning, and rain.

They're mostly composed of ice. And so basically the ice falls, and you have this pouches extending

sometimes hundreds of miles in any direction

Ice crystals help create these weird clouds too — called Fallstreak holes. Scientists

think they're created when ice crystals in a cloud form really quickly, and either

evaporate or sink to the ground.

So they leave this big hole around the center of the cloud.

Some clouds don't even come from nature:

These are called contrails — which just means “condensation trails.”

They're made of water vapor from a plane's exhaust, and mimic nature's wispy cirrus

clouds — meaning they are high up, and disappear really quickly.

Because clouds are above us we tend not to give them a second thought, but they are super

important because they not only regulate temperature on the planet, but they're also the primary

drivers of rain and precipitation, which we need to live.

For us cloud observers on the ground — it takes practice to identify clouds.

A good tip is to have a cloud chart. With a cloud chart it's very easy to at least distinguish

the clouds are at the bottom. And the clouds that you normally tend to see at the top of

the clouds are on the middle layers are probably the most tricky ones

There are lots of communities out there for cloud watchers — like the Cloud Appreciation

Society, which accepts submissions of clouds from all over the world and adds them to photo

galleries online. If you're ever stumped by a cloud, it might help to

look at it from above: The National Oceanic and Atmospheric Administration has a near-real-time

satellite view of clouds that you can access online. When you combine all these tools together, you can start making

predictions about your day, just based on the clouds above you.

I think those clouds mean that it will be nice for the next couple of hours. Those big,

white, wispy clouds up there mean that it is going to be nice.

The cloud chart we made for this video was super helpful when I was first learning to identify

clouds, especially when it came to telling the difference between the basic ones, like

cirrus, stratus, and cumulus. To download and print out your own cloud chart, like the

one we showed in this video, get permission from your guardian or parent to go to the

link below – or have them do it for you. Happy cloud hunting!