Radar was NOT invented to detect weather. Among its' first uses was during World War II. Radar units in England (United Kingdom / Great Britian) were able to get advance warning of Nazi air strikes during the Battle of Britain. They noticed that when it rained the radar screens were covered in a gray haze...and planes could not be detected! While scientists tried to get around the problem, weather forecasters quickly saw the advantages of the new invention! Weather radar was born!

Radar works by sending out a radio wave at a very high frequency. When the radio signal hits raindrops part of the signal bounces back to the radar. The signal travels at the speed of light (over 350,000 kilometers per second!).

Knowing exactly how fast the signal is traveling, means that we can tell how far away the rain is by timing how long it takes for the signal to travel to the rain and then bounce back to the radar. This happens so fast that most radars send out about 1000 signals (called pulses) each second!!

Doppler Radar:

Doppler radar is now being used by Meteorologists to learn even more about weather. Especially, dangerous weather like tornadoes. Doppler radar can not only see rain and other forms of precipitation. It can see the winds inside storms. In some cases it can even track bugs and dust particles and tell a forecaster what the winds are doing in areas where there is no rain. When tornadoes develop they blow rain drops around in a circle. Doppler radar can see the raindrops going in different directions and tell a forecaster precisely where the tornado is in some cases.

HOW DOPPLER RADAR WORKS:

Have you ever listened to a train whistle as it was coming toward you? Did you notice that the pitch of the whistle changes as it passes you and starts moving away? This change in the frequency of the sound is called the Doppler Effect. Doppler radar measures the very small changes in the frequency of the signals it receives to see determine winds. The radar can only see wind coming toward it or moving away from it, though.

NEXRAD

The National Weather Service has installed a new type of Doppler Radar called NEXRAD around the country. NEXRAD stands for NEXt Generation RADar. This radar produces many different views of storms and rain. We use Nexrad and our own Doppler radar at WHNT TV to track storms and keep or viewers alerted. Some of the images from these radar are now available on the internet in real time. I have links to some of them below!

Overview of the Doppler Radar System

Radar Tutorial

Learning Activities
	WSR-88D (NEXRAD)Terms & Acronyms (NEXRAD = Next Generation Radar)
	RADAR-ology
	Radar Meteorology - online guide

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