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📘 How radar works

Radar does not take a photograph of a storm; it times tiny radio echoes. From each return, it estimates a target’s range and direction, then leaves the interpretation to a computer.

3
lessons
~15 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. Radar Measures Range and MotionExplain how radar uses radio pulses, echo timing, antenna direction, and beam geometry to estimate where targets are.Radar estimates range, direction, and radial motion from returned radio energy, but its beam samples volumes with finite width and timing limits.
  2. Weather Radar Builds ProductsExplain how weather radar turns returned strength, radial motion, and repeated elevation scans into products.Reflectivity describes scatterers, Doppler describes radial motion, and volume scans sample those measurements at several heights.
  3. Radar Has Limits and UsesConnect police speed radar to Doppler measurement and identify limits and artifacts that complicate radar interpretation.A speed gun measures motion along its beam, while radar products can be distorted by angle, clutter, blockage, folding, and aliasing.

Questions this course answers

What does the delay between a radar pulse and its echo estimate?

The pulse travels to the target and back, so its round-trip time can be converted into distance after accounting for the two-way path.

What does a single fixed Doppler radar measure directly?

Doppler velocity is radial: it describes motion along the radar beam, not the whole velocity vector.

Why can an angled police-radar reading be lower than a vehicle’s full speed in stationary mode?

The cosine effect reduces the measured radial component when the vehicle’s path is not directly toward or away from the antenna.

Grounded in trusted sources

  • NOAA JetStream, How radar works: https://www.noaa.gov/jetstream/doppler/how-radar-works
  • NOAA NCEI, Next Generation Weather Radar (NEXRAD): https://www.ncei.noaa.gov/products/radar/next-generation-weather-radar
  • National Weather Service, How Does the Radar Work?: https://www.weather.gov/bmx/radar_aboutnwsradar_howdoesitwork
  • NOAA National Severe Storms Laboratory, A Guide for Interpreting Doppler Velocity Patterns: https://www.nssl.noaa.gov/publications/dopplerguide/chapter1.php
  • NHTSA, Speed-Measuring Device Operator Training: https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/radar_instructor_manual-smd-2018.pdf
  • NHTSA, Glossary: Speed Measuring Device Resources: https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/glossary_speed_measuring_device_resources-2018.pdf

Every Wunder lesson is built from real, reputable sources — never invented.

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