How Does Weather Radar Work?

Learn how to predict the weather for your area — no “weather frogs” needed.

By Ed Brotak
Published on July 9, 2024
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by Adobestock/WINDCOLORS

How does weather radar work? Learn how to predict the weather for your area with radar reflectivity imagery and learn how to spot a tornado on radar.

Meteorologists will tell you that weather radar is the best tool you can use to predict rain or snow in the next few hours – and they’re not the only ones who can use it. It’s not that hard to understand, and the web gives you access to weather radars 24/7. It can even warn you about impending thunderstorms and tornadoes.

What is Radar?

First, let’s talk basics. “Radar” is an acronym for “radio detection and ranging.” A radar set consists of a transmitter and a receiver. The transmitter sends out a pulse of energy (microwaves have replaced the original radio waves). If that pulse hits an object, a tiny fraction of that energy is reflected back. A receiver – the familiar radar dish – captures this energy. The signal is amplified and transformed into an image on a screen. By measuring the time between signal emission and return, a distance for the object can be determined.

Radar was a great asset during World War II in determining the location of enemy ships and planes, but there was one drawback: At times, the radar screen was obscured with large areas of radar returns, severely limiting its military advantage. These large areas on the radar screen were precipitation. Meteorologists immediately saw the potential for radar to be used as a weather-forecasting tool but were constrained by its military usage.

In the U.S., after a series of damaging East Coast hurricanes in 1954 and 1955, there was a greater impetus for implementing a radar network that could track these storms while they were still over the water. In 1957, the Weather Surveillance Radar (WSR-57) was developed and installed at numerous locations. In the 1970s, the more advanced WSR-74 units started to replace the older radars.

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