Type of clouds

Clouds are all made of the same thing: water droplets or ice crystals that form around dust particles floating in the air. But they don’t all look the same. That’s true! That’s because clouds get their shape and size from the air that surrounds them — different temperatures, humidity levels and winds cause different types of clouds to form. And different types of clouds bring different weather.

Let’s look at the four main types of clouds. See those puffy clouds, scattered throughout the sky? They look like… cauliflower! They do! These are cumulus clouds.

Cumulus clouds form when warm air containing water vapour rises from the ground, cools as it rises higher, and condenses into water droplets. Cumulus clouds form below 1,000 metres. They are low level clouds. Cumulus clouds aren’t always white like cauliflower; they can be grey, too. Thin clouds that contain fewer droplets let more sunlight through, and appear white; while thicker clouds let less sunlight through, and appear grey.

The thicker and heavier a cloud gets, the more likely it is to release its droplets... So grey cumulus clouds are a sign of rain, while the white fluffy ones come with fair weather. Look at those thin, wispy clouds high in the sky. They look as if someone took a cloud and stretched it, pulling pieces off. As if it were candy floss!

You’re right! These are cirrus clouds. Cirrus clouds are high level clouds; they form at 6,000 metres or higher. Up here, the air is very cold, so the water droplets that usually make up clouds turn to ice crystals. Those streaks you see across the sky are ice crystals falling from the clouds.

Since ice crystals fall fairly slowly, much slower than raindrops, the streaks are stretched out horizontally as well as vertically. Sometimes, these clouds take on the colours of the rising or setting sun, turning bright red, yellow... or pink, just like candy floss! A blue sky and a few cirrus clouds usually means it is going to be a clear, sunny day. Uh oh, look at that cloud moving in.

It’s like a huge, thick blanket covering the sky! That’s a stratus cloud. These clouds often bring rain if it’s warm, and snow if it’s cold. Stratus clouds form when the weather has been cold and warmer, moist air blows in. They can form up to 2,000 metres, or float very near the ground, as fog.

What do you notice about that cloud, Jenny? I notice it’s getting me soaked! This is a nimbus cloud, and nimbus clouds always have rain or snow falling from them. Sometimes you see them during a thunderstorm, too. Nimbus clouds can combine with other kinds of clouds, to form, for example, cumulonimbus.

A cumulonimbus cloud can begin at a low altitude and stretch to more than 20 000 metres, forming a huge, dark, puffy cloud with rain falling from it. Cumulus, cirrus, stratus, and nimbus: these are the four main types of clouds. And some of these can combine together to give us more cloud types. Weather experts, called meteorologists, track clouds using information from weather satellites in space. Watching different types of clouds can give clues about what is happening in the atmosphere, and what we can expect to happen in the weather.

But you don’t need to be a meteorologist to look at the clouds and predict the day’s weather. Take a look at the sky where you are. What clouds do you see?