Clouds and Precipitation

Clouds

• Form as warm air is forced upward, expands, and cools.

• Billions of tiny droplets of water and dust form a cloud.

• 3 main types of clouds: Stratus, Cumulus, and Cirrus

Stratus

• Forms at low altitudes• Clouds of flat layers, or smooth, even sheets• Stratus clouds near the ground are called FOG• Associated with fair weather, rain or snow

Cumulus

• Clouds are large, puffy, white clouds, often flat bases and may have gray centers.

• They grow upwards and tall• Associated with fair weather, snow or

thunderstorms

Nimbo or Nimbus

• Any cloud that produces precipitation.• Cumulonimbus “thunderheads” produce

thunderstorms.

Cirrus

• Cirrus clouds are the highest clouds.• They usually mean fair weather.• They look white and feathery.

Precipitation

• Water falling from the clouds• 4 different forms: Rain, Snow, Sleet and Hail• Air temperature determines which it will be

Rain

• Rain is when liquid water falls from the clouds• Rain will fall when temperatures are above

freezing.

Snow

• Snow forms when the temperatures are so cold that water vapor turns into a solid.

Sleet

• Sleet forms when raindrops pass through a layer of freezing air near the surface.

Hail

• Hailstones are pellets of ice that form inside a cloud

• Melt once they hit Earth’s warm surface