Radar altimetry, precipitation radar, doppler radar

The fundamentals of radar altimetry, precipitation radar, and doppler radar.

Radar altimetry

Radar altimetry measures the precise distance from a satellite or aircraft to the Earth's surface (land, ice, or water) by timing how long a radar pulse takes to bounce off the surface and return.

Precipitation radar

Precipitation radar sends out radar pulses. When it hits raindrops or snowflakes, some energy reflects back. The strength of the return signal tells you how intense the precipitation is. It also gives the vertical structure of storms (like how tall or thick clouds are).

Doppler radar

Uses doppler effect to measure velocity of objects by analyzing changes in frequency of radio waves. If raindrops are moving toward the radar: return signal frequency gets higher. If moving away: frequency gets lower. This shift = velocity of the rain/clouds = wind speed + direction.

Ground-based doppler radar

Used for wide-area weather surveillance and forecasting, detecting precipitation, wind shear, and severe storm features (e.g., tornadoes).

Airborne doppler radar

Installed on aircraft, Detailed storm observations. Providing real-time weather information for pilots, helping them navigate around storms and turbulence.

Satellite-based doppler radar

Measures 3D wind profiles and precipitation from orbit, offering global-scale atmospheric measurements. Rarer and trickier (because satellites move fast).