Cloud Formation and Types

• Clouds are visible masses of ice or condensed liquid water droplets suspended in the atmosphere.

Cloud Formation

• Cloud formation starts with water vapor condensing into liquid droplets.
• Clouds form when air becomes saturated and water vapor condenes around condensation nuclei (dust, soot).
• Enough vapor collection forms visible cloud droplets.
• Cloud droplets that become heavy enough will fall as precipitation.

Factors Influencing Cloud Formation

• Cloud type depends on temperature, altitude in the troposphere, and air moisture content.
• Warm air holds more moisture than cold air.
• Tropospheric air temperatures decrease with altitude, causing rising humid air to cool and condense.
• All clouds form and weather occurs in the troposphere.
• Uneven heating of earth causes constant movement of air masses with varying temperatures and moisture, and creates ever changing weather and cloud formation.
• Cold air masses moving into warmer air creates large clouds due to condensation.

Cloud Altitude Classifications

• Low altitude clouds: up to ~7,000 feet.
• Mid altitude clouds: ~7,000 to 17,000 feet.
• High altitude clouds: ~17,000 to 35,000 feet.

Cloud Classification

• Meteorologists classify clouds by shape, altitude, and characteristics.
• Cumulus: puffy.
• Stratus: flat and layered.
• Cirrus: wispy.
• Nimbus: rain-bearing.
• Alto-: mid altitude.
• Cirro-: high altitude.

Basic Cloud Types

• Cumulus (Cu)
• Stratus (St)
• Stratocumulus (Sc)
• Cumulonimbus (Cb)
• Altocumulus (Ac)
• Altostratus (As)
• Nimbostratus (Ns)
• Cirrus (Ci)
• Cirrocumulus (Cc)
• Cirrostratus (Cs)

Cumulonimbus Clouds

• Also called thunderheads.
• They form vertically from low to high altitudes.
• These clouds are created as warm air rises, cools, and condenses.

Cirrus Clouds

• Located at the highest altitudes (17,000 - 35,000 feet).
• Very thin and made of ice crystals.
• Cirrocumulus clouds appear in patterns resembling fish scales.
• Cirrostratus clouds are thin, veil-like clouds covering the sky.
• Cirrus clouds can indicate upcoming weather changes.

Stratus Clouds

• Flat, sheet-like clouds covering all or part of the sky.
• Gray, low altitude clouds that can persist for days.
• Altostratus clouds are similar but in the mid-altitude range.
• Nimbostratus clouds are rain-bearing stratus or altostratus clouds.

Cumulus Clouds

• Rounded and puffy clouds.
• Low altitude clouds, white with uneven rounds at the top, darker and flattened at the bottom.
• The flat bottom indicates the level of vapor condensation.
• Shapes constantly change as they move, due to vapor condensing on rising air.
• Stratocumulus: low altitude cumulus clouds in larger patches or sheets/layers.
• Altocumulus: cumulus clouds in the mid-altitude range, appearing smaller.

Cumulonimbus Clouds (Thunderheads)

• Form when cold air moves into warm, humid air.
• Warm air rises over colder air, condensing into droplets.
• Warm updrafts carry air high into the sky.
• They begin at low altitudes and extend into very upper altitudes.
• Often associated with rain and severe weather.

Nimbus Clouds

• Nimbus clouds bring rain.
• Cumulonimbus clouds are associated with rain, thunderstorms, and severe weather.
• Nimbostratus clouds are thick, gray, layered stratus clouds that obscure the sun.
• Typically form at mid to lower altitudes.