Download Slide 1 - St. Francis Cathedral School

What are
clouds?
Clouds are big areas of very tiny droplets of water or ice crystals.
The droplets are so small and light that they can float in the air.
Let's let Tim and Moby explain...
But how are they formed?
Did you know that all air has little bits of water in it? (Usually in
the form of water vapor)
When that warm air rises up into the atmosphere it expands and starts to cool down.
Since cooler air can't hold as much water vapor as warm air, the vapor condenses (shrinks) together and
sticks to tiny pieces of dust floating the in air.
This forms a tiny droplet, and when many of these are clumped together-they make a cloud!
There are 3 main types of clouds:
Cumulus
Stratus
Cirrus
Cumulus clouds are what we usually think of when we think of clouds.
The word cumulus means "big and round"
They are big fluffy white clouds, made from tiny droplets of rain. They can be found lower in the sky, but
can grow vertically! They bring fair weather.
Stratus clouds are flatter, denser clouds that cover a large area.
The word stratus means "sheet" or "blanket"
Stratus clouds are low lying clouds.
Cirrus clouds are thin and wispy.
The word cirrus means "feather"
They are high up in the sky and are formed from ice crystals. They mean fair to pleasant weather,
but usually a weather change comes in 12-24 hours.
High
Cirrus
Middle
Low
Stratus
Cumulus
There are other types of clouds that are mixes of the 3 main types:
High Clouds: Cirrostratus, Cirrocumulus
Middle Clouds: Altostratus, Altocumulus
Low Clouds: Stratocumulus, Nimbostratus
Low-High: Cumulonimbus
Cirrostratus clouds are thin, sheetlike high clouds. They are so thin that the sun and moon can be
seen through them.
They often cover the entire sky.
Cirrostratus clouds usually come 12-24 hours before a rain or snow storm.
Cirrocumulus clouds are small, rounded white puffs that form in long rows.
Some people think they look like fish scales.
Cirrocumulus clouds are normally seen in winter, in cold but fair weather.
Altostratus clouds are gray or blue-gray and usually cover the whole sky.
They are mid level clouds (alto) made of ice crystals and water droplets.
Altostratus clouds are usually seen before storms with a lot of rain or snow.
Altocumulus clouds are gray puffy clouds. They appear in groups, and sometimes make parallel
bands across the sky.
They are mid level (alto) and are made of water droplets.
On a warm humid morning, altocumulus clouds mean a thunderstorm is coming later!
Stratocumulus clouds are low, puffy and gray.
Most form in rows with blue sky visible in between them.
Rain rarely occurs with stratocumulus clouds, however, they can turn into nimbostratus clouds.
Nimbostratus clouds are a dark gray, wet looking cloudy layer.
They are associated with continuously falling rain or snow, that falls light to moderate.
Cumulonimbus clouds are storm clouds. They are sometimes called Anvil Clouds because wind can flatten the
top of the cloud into an anvil-like shape.
Cumulonimbus clouds produce heavy rain, snow, hail, lightning, and sometimes tornadoes.
Did you know the anvil points in the direction the storm is moving?
High
Cirrostratus
Cirrus
Cirrocumulus
Cumulonimbus
Middle
Altocumulus
Altostratus
Low
Stratus
Nimbostratus
Stratocumulus
Cumulus