Mr. Hartwell -- F-M Meteorology

Cloud Types &Properties

Clouds• Formed when moist air is cooled

enough to allow saturation & condensation to take place.

• Saturation: air is completely filled with water vapor

• Condensation: phase change from gas to liquid

Clouds cont.

• Different types form based on:• Amount of moisture in the air• Vertical air temperature through troposphere• Character of rising air (speed & location)• Approaching weather systems

• Identified by:• Shape• Height• Composition• Character (puffy vs. layered)

Classification—Type #1• Cirrus —feathery, wispy, thin

Classification—Type #2

• Cumuliform —puffy, round, pretty

Classification—Type #3

• Stratiform —layered, sheet-like, strata=layers (like

rocks)

Classification—Type #4

• Nimbus —produces precipitation

Heights (HIGH): CIRRUS (Ci)

• Cirrus — made of ice crystals

• Align with upper level winds

• Indicate fair weather conditions

Aka: Mare’s Tails (look like horse’s tails)

Heights (HIGH): Cirrocumulus (Cc)

• Cirrocumulus — ice crystals

• Occur in moist & unstable air (aloft)

• Appear with precip.-causing weather (warm fronts)Aka: “Mackerel sky, not three days dry”

Heights (HIGH): Cirrostratus (Cs)

• Cirrostratus — ice crystals

• Common in winter with precip.-causing weather

• Produce sun dogs & halos

Sun Dog Halos

Heights (Middle) : Altocumulus (Ac)

• Occur in moist air that is lifting

• Fist-thumb-pinkeytip rule

• Altocumulus = thumb size

• Signals approaching storm system

Heights (Middle) : Altostratus (As)

• Layered; liquid water

• Gray to pale blue

• Occurs where moist air is rising slowly

• Just ahead of rainy weather

Heights (Low) : Cumulus (Cu)

• Puffy, white, pretty

• Indicates fair weather

• Well-defined bases

• Caused by humid air rising in bubbles

Heights (Low) : Cumulus Congestus

• Aka: towering cumulus

• Atmosphere is very unstable

• Indicates stormy conditions later in the day

Heights (Low) : Status (St)

• Sheet cloud; layers

• Hovers just above the ground (was fog?)

• No precip., but may be misty

Precipitating Clouds: Nimbostratus (Ns)

• Same as stratus, just precipitating

• Precedes warmth (occur before warm fronts)

Precipitating Clouds: Cumulonimbus (Cb)

• Thunderstorm!• Can poke into

stratosphere• Associated

with severe weather

• Anvil shape tops with mammatus clouds

Precipitating Clouds: Cumulonimbus (Cb)

Precipitating Clouds: Cumulonimbus (Cb)

Mammatus cloud (below)

Anvil shape (above)

Miscellaneous: Contrails

Miscellaneous: Fallstreaks

Formation: Sublimation of falling ice crystals carried by winds aloft