Definition
An airborne or ground-based radar system that transmits radio energy and detects the reflections from precipitation particles, displaying the location, intensity, and movement of rainfall, hail, and other precipitation so pilots and controllers can identify and avoid hazardous weather, particularly thunderstorms.
Plain English
Equipment that sends out radio signals and shows where rain and storms are by picking up the signals that bounce back. The heavier the precipitation, the brighter the return on the screen.
Context Anchor
Seen in thunderstorm avoidance, instrument flying, and cockpit weather-display discussions.
Derivation
Radar comes from RAdio Detection And Ranging — a system developed in the 1930s and 40s that uses radio waves to find objects and measure how far away they are. Weather radar applies the same principle to precipitation rather than aircraft or ships.
Why Pilots Care
Allows pilots to detect and avoid hazardous thunderstorm cells that may not be visible to the eye.
Grounding Statement
If the display shows a strong area of precipitation ahead, the pilot treats that area as a warning sign and plans a safe path around it.
Intuition Check
Weather radar does not mean “radar that shows all weather.” In this context, it mainly shows precipitation, so clear-looking areas can still contain hazards such as turbulence, hail, or building clouds.
Example Sentence 1
The pilot used the onboard weather radar to pick a path around a line of building thunderstorms ahead.
Example Sentence 2
In the preflight briefing, the crew reviewed the weather radar imagery to plan a route that avoided convective activity.