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 or rain or snow

Cumulus Clouds are large, puffy, white clouds, often flat bases and may have gray centers They grow upwards, tall Associated with fair weather, snow or thunderstorms

Nimbo or Nimbus Any cloud that produces precipitation. Cumulonimbus “thunderheads” produce thunderstorms. Nimbostratus are stratus clouds that have precipitation in them. Dark or Gray in color Nimbostratus Cumulonimbus

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 temperatures determine which it will be.

Rain and Snow Rain drops falling in Temps Above Freezing. Snow forms When the Temps 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.

Air Masses Large bodies of air that form over land or oceans. H and L They move, but do not mix. Fronts are the boundaries where two different air masses meet. 4 types of fronts: Cold Front, Warm Front, Stationary front, and Occluded Front.

Cold Fronts Occurs when cooler air moves toward warm air. May produce short periods of severe rain or snow. Forms cumulus type clouds Temperatures may drop, winds may change direction, barometer may begin to rise Symbol on weather map:

Cold Front: Warm air is abruptly pushed upward, cooling, condensing moisture into cumulus or cumulonimbus clouds                                                                               

Warm Front A warm front is when warm air moves over heavier, colder air. First indicator is cirrus clouds. Maybe extended periods of snow or rain falling. As is passes through temps may rise. Symbol on the weather map:

Warm Front Notice the angle of slope between the two air masses.

The weather during a WARM FRONT starts with cirrus clouds about 24-48 hours before the rain begins. Cirrus clouds are “at the front of the front”

Stationary Front A stationary front is drawn when the boundary between the two air mass is not moving. This type front usually stays around longer.