FAA En‑Route Radar Controller Certification (CKT-2) Practice Test

The area of precipitation returns associated with a thunderstorm on a radar screen is typically smaller than the actual cumulonimbus cloud. This occurs due to the nature of how radar detects precipitation. The radar primarily picks up the precipitation particles, such as rain droplets, while the cloud itself can extend far beyond where the precipitation is occurring.

Cumulonimbus clouds, which are associated with thunderstorms, can have an extensive vertical development and can contain a variety of weather phenomena. The radar can show an area of intense precipitation that might not encompass the full structure of the cloud, especially in cases where the updrafts and downdrafts within the thunderstorm create variations in precipitation distribution.

Therefore, while the cumulonimbus cloud may spread out considerably in the atmosphere, the radar might only capture a portion of that cloud where precipitation is occurring, leading to radar returns that are often smaller than the actual cloud size. This concept is important for pilots and air traffic controllers as they assess the size and impact of thunderstorms based on radar data.