Clouds
How do clouds form?
As air rises and cools, it becomes more dense and can hold less
water vapor.
The water vapor molecules condense onto a solid particle and
Warm air is less dense than cold air so it can hold more water vapor.
form liquid water droplets or ice crystals
How do clouds form?
Form Clouds
Thousands of these tiny water droplets or ice crystals
together in the air…
Liquid water that condenses from the air onto
a cooler surface is called dew.
Water vapor that condenses onto a surface
that is below freezing is called frost.
There are 3 main types of clouds classified by shape
Cirrus
Cumulus Stratus
Pictures courtesy of Windows to the Universe, http://www.windows.ucar.edu
Cirrus clouds are wispy, feathery clouds that are typically made
of ice crystals and form at high altitudes. These are often
referred to as Mare’s tails.
Pictures courtesy of Windows to the Universe, http://www.windows.ucar.edu
Cumulus clouds look like fluffy rounded balls of cotton. They
are low level clouds that typically indicate fair weather.
Picture courtesy of www.wildwildweather.com
Stratus clouds form in flat layers and ‘blanket’ the sky at low altitudes.
Light mist or drizzle are typically associated with Stratus clouds.
Picture courtesy of www.wildwildweather.com
Prefixes or suffixes added to the names of the 3 main
types of clouds further classify them by weather
conditions or altitude.
Altocumulus Clouds Altostratus Clouds
Clouds that form between 2 and 6 kilometers above earth’s
surface have the prefix, ‘alto’. These are mid-level clouds.
Prefixes or suffixes added to the names of the 3 main
types of clouds further classify them by weather
conditions or altitude.
Nimbus used as a prefix or suffix indicates clouds bearing rain.
Cumulonimbus clouds are towering clouds with a flat top and grey
bottom, often formed in the shape of an anvil. These are also known
as thunderheads because they typically bring thunderstorms.
Prefixes or suffixes added to the names of the 3 main
types of clouds further classify them by weather
conditions or altitude.
Nimbus used as a prefix or suffix indicates clouds bearing rain.
Nimbostratus clouds are darker grey than regular Stratus clouds and
are a strong indicator of precipitation.
Stratus clouds that form at or near
the ground are known as fog.
Clouds Summary
Cloud classification Fair Weather Drizzly or misty Stormy
High Altitude
Cirrus
(Mare’s tail)
Medium Altitude
Altocumulus Altostratus
Low Altitude
Cumulus Stratus Nimbostratus
Tall (Bottom is low but
towers to medium / Cumulonimbus
high altitude) (Thunderhead)
Stratus clouds that form at or near the ground are known as fog.