Doppler Radar - Nov 30, 2007

Last Update: 12/28/2007 11:55 pm

     The name came from the person who first noted then documented the effect
of the frequency change of objects moving towards and then away from
a person.   His name was Johann Christian Andreas Doppler.

     In 1842, the Austrian physicist and mathematician authored an article on the
change in frequency and wavelength of an object moving towards an observer.
The original work focused more on light frequency of stars, but the “Doppler
effect” was of this change and was verified and confirmed by other scientists

later.

We’ve all experienced the Doppler effect. Next time you are parked in
your car waiting on a train, note how the sound of a train’s blaring horn
changes pitches as it approaches the intersection as to how it sounds as it moves
away. Turns out the same principle can be used in radars to note if particles are
moving towards or away from the radar. There is also a change in the
electromagnetic radiation that radar sends out. Doppler radars process this

change to detect the speed and direction of the winds in storms.

In the late 70s research meteorologists began to experiment with frequency change inside thunderstorms. At the University of Oklahoma, they did some of
the preliminary research on Doppler radar by constructing then testing a small hand
held parabolic dish, about the size of a very large salad bowl. Meteorologists
wore headphones and pointed the listening device towards mesocyclone and noted

the sound change as the air was moving towards and away from them.

It all sounds pretty primitive now, but then it was cutting edge technology. Today
Doppler radar evaluates the change in the electromagnetical signal that is returned to
the radar, and gives us an idea of not only where a storm is located, but which
way the winds inside the storm are moving. This allowed us to give earlier

warnings of tornadoes and destructive winds.

I once read a biography on Doppler, as I recall it said his father was a stone
mason, but young Doppler was too weak to follow in his father profession, so he
became a math wiz at a very early age. He studied very hard and as a result of his

work helped us better understand science. What a good lesson for young folks, follow your heart, find out what you are good at, work very hard to educate yourself, and the things you do may just benefit other people for years to come. He was no stone mason, but I’ll bet his daddy was very proud of him.

If you have a weather question send it to askdan@kjrh.com.

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