Clouds Cloud Formation Condensation water vapor gathers and

Clouds

Cloud Formation § Condensation - water vapor gathers and forms water droplets or ice crystals (deposition) § 1) Warm air rises taking along vapor, cools and condenses § 2) Molecules (dust, salt, ash – condensation nuclei) combine with water vapor and form droplets

Where clouds form § Word parts indicate where clouds form and describe appearance – Strato – layered clouds, usually form below 6, 500 feet – Cumulo – fluffy clouds that grow upward – Alto - between 6, 500 and 20, 000 feet – Cirro – feathery clouds forming above 20, 000 feet – Nimbo – refer to dark rain clouds

Where clouds form

High Level Clouds § Bases above 20, 000 ft (7, 000 m) § Composed of ice crystals § Types: Cirrus, cirrocumulus, cirrostratus

High level clouds: Cirrus Clouds § Thin, wispy, and fibrous, hair-like in appearance § Indicate fair weather

High level clouds § Cirrocumulus – extremely high – Occur before snowfall, made entirely of ice § Cirrostratus – indicate snow or rain, blanket sky – Produce halos around Sun and moon

Middle level clouds § Bases between 6, 500 and 20, 000 ft § Associated with light precipitation § Contain ice crystals and/or water droplets § Types: Altocumulus and Altostratus

Middle level clouds: Altocumulus § Puffy with noticeable height piling upward § Commonly followed by thunderstorms

Middle level clouds: Altostratus § More uniform coverage, still layered § Gray or bluish in color § Indicates an approaching thunderstorm or cyclone

Low Level Clouds § Bases lie below 6, 500 ft (2, 000 m) § Mostly water droplets § Some ice crystals in cold climates § Types: Nimbostratus, Cumulonimbus, Stratocumulus, Stratus, and fog

Low level clouds § Nimbostratus – Dark gray, layered clouds – Produce steady rain § Cumulonimbus – Also low level, but produce heavy rain, thunder, lightning, or hail

Low level clouds: Stratus Clouds § Substantial, flat or layered § Appear before thunderstorms, but produce little precipitation § Usually the lowest § Appear overcast

Low level clouds: Stratocumulus § Layers of puffy clouds, flat on top § Often cover sky in winter § Can produce precipitation

Low level clouds: Fog § “Cloud” that is touching the ground § Becomes stratus when it lifts