clouds

How do they form?• Clouds form as warm air is forced

upward, expands, and cools.

• When warm, moist air cools, the water vapor turns into liquid

droplets or freezes into ice crystals depending on the temperature.

• These droplets and crystals come together to form…clouds!

How are they classified?• By SHAPE and HEIGHT

• The shape and height of clouds depends on: temperature,

pressure, and the amount of water vapor in the atmosphere.

• By the way…how many layers of the atmosphere are there?

What shapes do clouds come in?3 main cloud shapes:

• STRATUS form layers, or smooth even sheets in the sky

• CUMULUS puffy, white clouds with flat bottoms

• CIRRUS curly, wispy, and look like they are made of thin fibers

Stratus clouds…•Form layers, or smooth even

sheets in the sky

• Usually at low altitudes below 2,ooom

• Often cover large areas & block out sun, Can mean continuous heavy rain or steady drizzle.

•Fog is a type of stratus cloud that is very low to the ground

• Strato- is a prefix that describes low altitude clouds

cumulus clouds…•White, puffy clouds, with

flat bottoms

•Form when warm air rises

• Usually at mid-altitudes (2000-6000m), but

sometimes tower to great heights

• Usually means fair weather or thunderstorms

(cumulonimbus clouds)

• Curly, wispy, and look like they are made of thin fibers

•Form when the wind is strong, usually indicate a possible change in

weather.

• Usually at high altitudes (6,000-8,000m)

• Usually mean fair weather, but can indicate approaching storms

• Made of ice crystals

• Cirro- is a prefix that describes high altitude clouds

cirrus clouds…

Cloud prefixes…

Clouds are also classified by their height:

• Cirro- = high clouds

• Alto- = mid-elevation clouds

• Strato- = low clouds

• EXAMPLE: cirrostratus clouds are high clouds that look like flat

sheets or layers in the sky

Last, but not least…Some clouds are known as “rain

clouds”:

• Clouds associated with precipitation often have the word NIMBUS attached to

them.

• Nimbus is Latin for “dark rain cloud”

•Nimbus clouds are generally found at very low altitudes

•EXAMPLE: When a cumulus cloud grows into a thunderstorm, it is called a

cumulonimbus cloud. Nimbostratus clouds are layered rain clouds.