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
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
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.
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