Weather Radar 101

Have you ever seen the commercials for your local television station promoting their new weather radar system and wonder what that means to you? Weather reporters use these tools to show viewers where the precipitation is occurring and to show its intensity. Meteorologists can also analyze the data from the weather radar to make predictions. When you’re watching Doppler radar weather reports on television or viewing live weather radar images on the Internet, color-coded patches on the screen show you exactly where the severe weather is occurring, as it occurs.

What exactly is a Doppler radar? Weather systems such as rain or snow can be viewed using radar. The radar emits a burst of energy and then listens to see if that energy is reflected back. For example, if the energy burst hits an object such as a rain drop or even a bird, the energy scatters. Some of the scattered energy bounces back to the radar. Once the signal is received, it is analyzed for strength, travel time and phase shift. These calculations take place about 1,300 times per second.

Tips For Reading Weather Maps

Deciphering the Weather Forecast

The phase shift of energy pulses is affected by the direction that the object (such as a raindrop or bird) is moving. Weather radars that can detect this so-called “Doppler affect” are called Doppler radars. Just as you can hear the Doppler affect when a train travels past you, the Doppler radar can measure this affect on the reflected energy pulses and can compute the motion into velocity. This is useful in estimating wind speed and predicting tornados.

Reading Weather Radar Images
When viewing live weather radar images, you’ll notice that the intensity of precipitation is shown using different colors. For example, light showers show up as a light blue color with stronger rain showing up in green. Higher intensity rains show up in orange and red, progressing all the way up to hot pink for the most intense storms.

How the Weather Center Works

Radar for weather also involves complex computer systems that use algorithms to analyze the data. These algorithms are able to estimate total mass of precipitation, potential wind gusts, possibility of hail and probable size of the stones, wind shear, possibility of tornados, and wind direction and speed. Many weather radar computer programs even include the ability to animate the data.

In addition to picking up data from raindrops, hailstones and snowflakes in the sky, weather radar also picks up other objects including birds, insects, airplanes, buildings, mountains, building reflections and other types of “ground clutter.” Migrating birds are commonly seen on weather radar between February and May and August and November. These false echoes are often removed by the weather radar software to make the image less confusing to viewers.

Understanding Meteorology

Weather radar has been in use since World War II. It has evolved into a useful tool that allows meteorologists, television weather reporters and weather hobbyists to take a look at current weather conditions and view real-time precipitation. The science behind weather radar systems is complex, but viewing the images is easy thanks to computer algorithms and software that compile the final images.

A Modern Look at the Weather Almanac