The reflectivity scale uses dBZ, a logarithmic measure of returned radar signal. Larger drops and hail can make strong echoes, so echo strength alone cannot tell exactly how much rain reaches the ground. The historical image is an observation; the moving pulse beside it is a separate explanatory drawing.
Weather and climate · Discover & try
What do weather-radar colours really show?
Reading level 2 of 5 · DevelopingChange
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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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