Clouds and Precipitation

Cumulus

A type of cloud characterized by fluffy, white, cotton-like appearance. These clouds usually indicate fair weather but can grow into larger storm clouds under the right conditions.

Nimbus

A type of cloud that produces precipitation, such as rain or snow. Nimbus clouds are dense and dark, often signaling storms.

Nimbostratus

Thick, dark clouds that produce continuous precipitation, usually rain or snow, often covering the sky.

Orographic Cloud

Clouds formed as moist air is forced to rise over a mountain range.

Lenticular Cloud

Lens-shaped clouds formed over mountain peaks due to orographic lift and wave patterns in the atmosphere.

Noctilucent Clouds

Rare, high-altitude clouds visible at twilight, made of ice crystals in the mesosphere.

Virga

Precipitation that evaporates before reaching the ground, often seen as streaks beneath clouds.

Cloud Condensation Nuclei (CCN)

Tiny particles like dust or salt that water vapor condenses onto to form cloud droplets.

Dendritic Growth Zone

The temperature range in clouds favorable for the formation of snowflakes with complex, branched shapes.

Precipitation

Any form of water—rain, snow, sleet, or hail—that falls from clouds to Earth. Precipitation is a critical component of the water cycle.

Hail

Precipitation in the form of balls or lumps of ice, formed in strong thunderstorms with intense updrafts.

Rain Shadow

A dry area on the leeward side of a mountain range caused by precipitation being blocked by the mountains.

Lake-Effect Snow

Heavy snow caused when cold air moves over warmer lake waters, picking up moisture and depositing it downwind as snow.

Snow Squall

A sudden, intense snowfall event accompanied by strong winds, leading to rapidly reduced visibility and hazardous driving.

Yield (in precipitation)

The total amount of precipitation collected over a period. Yield measurements help assess rainfall and snow accumulation.

Glaciation

The process by which supercooled water droplets freeze to form ice crystals within clouds.

Graupel

Soft, small pellets of snow coated with rime ice, formed when supercooled water droplets freeze onto snowflakes.

Hydrometeor

Any form of condensed water or ice particles in the atmosphere, including rain, snow, hail, and drizzle.

Liquid Water Content (LWC)

The amount of liquid water contained in a cloud or fog per unit volume, important for understanding cloud properties and precipitation potential.

Nucleation

The initial process by which water vapor condenses onto particles in the atmosphere to form cloud droplets or ice crystals.

Optical Depth

A measure of transparency or opacity of the atmosphere or clouds to radiation. High optical depth means less radiation passes through.

Snow Grain

Small, opaque grains of ice precipitation typically formed in cold fog or light snow.

Sublimation

The process where ice changes directly into water vapor without becoming liquid first, important in dry and cold climates.

Wet Deposition

The process by which pollutants are removed from the atmosphere by precipitation.