What does a weather radar reflectivity scan primarily indicate, and how does it differ from a velocity scan?

• A. Reflectivity shows cloud altitude.
• B. Velocity shows precipitation intensity.
• C. Reflectivity shows precipitation intensity.
• D. Velocity shows cloud height.

Answer: (C)

Reflectivity measures how much radar energy is bounced back by targets in the air. The amount of returned energy increases with the size and number of hydrometeors (like raindrops, snowflakes, hail), so higher reflectivity values correspond to heavier precipitation. It doesn’t directly tell you cloud altitude; altitude is inferred from other data such as echo tops or vertical profiling.

A velocity scan, on the other hand, uses the Doppler shift of the returned signal to determine how fast targets are moving toward or away from the radar. This reveals wind speed and direction and can show motions within the storm, such as rotation or shear, rather than how much precipitation is present.

So the primary takeaway: the reflectivity scan indicates precipitation intensity, while the velocity scan indicates motion (wind), not precipitation amount.