Clouds, Precipitation & Weather Radar

These flashcards cover key terms and concepts from the lecture on clouds and precipitation.

Contrails

Bright white streamers of ice crystals formed in the exhaust of jet aircraft flying at high altitudes.

Cloud Condensation Nuclei (CCN)

Aerosols or ice crystals necessary to form cloud droplets.

Hygroscopic Nuclei

A special category of CCN that have a chemical reaction with water molecules, triggering condensation below 100% relative humidity.

Supercooled Water

Liquid water that remains in liquid form at temperatures below freezing.

Terminal Velocity

The constant speed of a particle falling through a motionless fluid caused by gravity and air resistance.

Cold Clouds

Clouds that lie completely above the 0°C isotherm.

Warm Clouds

Clouds that lie completely below the 0°C isotherm.

Precipitation

Water in solid or liquid form that falls from clouds to Earth's surface.

Acid Rain

Rain that has been made acidic by pollution, primarily sulfur dioxide and nitrogen oxides.

Doppler Effect

A shift in frequency of waves from a moving source, used in weather radar to determine wind movements.

Riming

The process where supercooled drops freeze upon contact with an ice particle.

Virga

Streaks of water or ice crystals falling from clouds that vaporize before reaching the ground.

Kelvin-Helmholtz Waves

Waves formed in a stable atmosphere along the interface between two layers of air moving at different speeds.

Fog

Suspension of tiny water droplets reducing visibility, typically to less than 1000 m.

Haze

A layer of dust and salt particles in the atmosphere, often mixed with water droplets.

Cloud Classification

The systematic categorization of clouds based on appearance, altitude, temperature, and composition.