A weather radar sends out pulses and listens for echoes. Rain, snow and hail can send some energy back. Colours on a reflectivity image group the strength of those echoes. Read its legend: a brighter colour is not a direct reading of wind speed or proof of a tornado.
Weather and climate · Discover & try
What do weather-radar colours really show?
Reading level 1 of 5 · EarlyChange
Word help
Reflectivity
A measure related to the strength of radar energy returned by targets.
dBZ
The logarithmic unit used on many weather-radar reflectivity displays.
Backscatter
Energy scattered back toward the instrument.
Watch · Try · Explain
See how it works
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Dated NOAA historical reflectivity imagery; pulse movement is a separate schematic.
What to look for
- Read dBZ rather than wind speed.
- Keep the historical image separate from the pulse sketch.
- Compare distinct dated events without calling them a time sequence.
Explain what you noticed
A different radar image has a strong reflectivity echo. What is the justified first conclusion?
Keep this idea: Reflectivity colours represent returned radar power, not a direct map of wind speed or guaranteed rain at the ground.
Follow the sources
- NOAA — Reflectivity
- NOAA / National Weather Service — Hurricane Ida Service Assessment, Figure 2
- NOAA / National Weather Service — Anniversary of the 2020 Midwest Derecho
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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