Identify what the instrument measures
The US National Weather Service explains radar through transmitted pulses and returned energy, with products that help analyse precipitation and other targets. Its satellite guidance distinguishes visible reflected-light imagery from other channels. A satellite cloud view and radar reflectivity therefore do not measure the same thing.
Do not infer rainfall from the whiteness of a cloud image alone. Likewise, a coloured radar return needs its product legend and interpretation rather than a generic assumption that every colour is rain intensity.
Read the product, not just the colours
NWS describes radar returns that can include non-precipitation targets and clutter. Its imagery guidance also notes differences among satellite channels and their uses. A familiar colour can mean different quantities on reflectivity, velocity, infrared or other products.
If the presenter switches graphics, reread the legend. A red patch on one product cannot automatically be compared with a red patch on another. Keep the timestamp, units and geographic coverage attached to each image.
Distinguish observation from extrapolation
A programme can animate recent observations and then continue into a forecast. Follow the frame labels to identify where the evidence type changes. A moving map is not necessarily showing only measured conditions, and a forecast frame does not become an observation because it follows observed images smoothly.
Also check whether the radar map shows one site, a composite or another processed product. The coverage and limitations can differ. A blank-looking area is not enough by itself to establish that the weather there is clear.
Use the distinction responsibly
For a programme note, save the product type, source, time and the claim made by the presenter. Consult the official explanation when the graphic’s meaning is unclear. This article gives no current weather assessment or activity advice; current decisions require the relevant official service’s latest information.
When sharing a screenshot, retain the legend and time rather than sending only a dramatic coloured region. A precise description says whether the image shows cloud appearance, radar reflectivity or another measured or modelled quantity. That keeps a useful weather explanation from turning two different instruments into a misleading single picture.
Related questions
Does satellite cloud cover prove rain reaches the ground?
Not by itself. Read the relevant products and official interpretation.
Does red mean the same thing on every weather map?
No. The product’s own legend defines it.
Sources and scope
Scope notes distinguish published documentation, supplied information and editorial methods. They do not report a hands-on service test.
- NWS: radar — Primary explanation of returned energy and types of information.
- NWS: satellite imagery types — Distinguishes visible and other satellite imagery.
- NWS radar and satellite guidance — Examples of product uses and non-precipitation/clutter limitations.
