Clouds

What are clouds?

A cloud is a large collection of very tiny droplets of water or ice crystals. The droplets are so small and light that they can float in the air!

How are clouds formed?*All air contains water.*Water near the ground is in the form of a gas called water vapor. *Warm air rises, expands and becomes cooler air.

It is kind of like the warm steam from a cup of coffee. We have seen the warm steam rise. That will help us remember that warm air rises, but what happens when the steam gets cooler?

It holds on to anything to keep from falling!

Hmmm…but, there is nothing in the air to hold on to…or is there?

What about the dust floating in the air?

Water vapor that has cooled does exactly that!

It holds onto dust particles or pollution in the air.

Since, water vapor is made up of tiny droplets of water. It combines with the dust and becomes a

tiny droplet of water holding onto dust.

When all of these water vapor/dust droplets come together….they become a visible cloud!

Why are clouds white?• Clouds are white because they reflect the light

of the sun. Light is made up of all of the colors of the rainbow and when you put them together, you get white.

• The sun appears yellow because it sends out more yellow than any other color.

• Clouds reflect all of the colors with the exact same amount, so they look white.

Why do clouds turn gray?

• If clouds get thick or high enough, all of the light above does not make it through the cloud. It starts to look gray or dark.

• If other clouds are around, their shadow can add to the gray to make it look even darker.

Why do clouds float?• The water vapor that is rising from the ground,

rises because it is getting warm.• It gets warm from the sun!• As long as the cloud and the air that its made

of is warmer than the outside air around it, it floats!

What causes rain?• If the air inside the cloud gets cooler than the

outside air around it and becomes too heavy, due to the amount of droplets, it rains.

• The rain causes the cloud to at least partially disappear because part of the droplets that made up the cloud fell to the ground.

Would you like to be able to predict the weather by looking at the clouds?

Some weather forecasters or meteorologists do just that!

Before you can do it…you need to know the three major types of clouds.

• Cirrus

• Stratus

• Cumulus

Cirrus Clouds• High clouds• Thin, wispy clouds blown in high winds into

long streamers• Usually white and predict fair to pleasant

weather• Often cover the entire sky

Stratus Clouds• Low clouds• Look like flat sheets of clouds and usually the

same color• Covers most of the sky• Usually predict overcast or rainy weather

Cumulus Clouds• Low clouds• Look like big, fluffy balls of cotton; Usually flat on the

bottom, but have very lumpy tops• Usually mean weather will be nice, however, sometimes

they can get very tall and turn into thunderheads• Form alone and there is a lot of blue sky between the

clouds

What do you know about clouds?

• Clouds are made up of warm water vapor droplets.• When the droplets start to cool, they attached to dust particles.• As long as the sun keeps the droplets warmer than the outside

air around the cloud, it floats.• If the air inside the cloud gets cooler than the outside air

around it and becomes too heavy, due to the amount of droplets, it rains.

• The rain causes the cloud to at least partially disappear.• Clouds are white because they reflect all of the colors of light at

the same time.• Clouds turn gray if it is too thick or high that the light above it

can’t get through the cloud.

And…

• There are three major types of clouds.– Cirrus (means high in the sky & pleasant weather)– Stratus (means low in the sky & rainy/snowy

weather)– Cumulus (means low in the sky & pleasant

weather----but, it could turn vertically into a thunderhead)