Valley Science: Doppler Weather Radar at Phoenix Mesa Gateway Airport

Dear Students,

About a mile south of the Phoenix Mesa Gateway airport near Sossaman Road looms a giant golfball on stilts. Surrounded by an expanse of hard baked dirt against the Superstition Mountains, the golf ball captured my curiosity. One more strange feature of this strange land. I went online to solve the mystery and learned that it is one of the 155 WSR-88D Doppler radar across the country sponsored by the National Weather Service.

The WSR (Weather Surveillance Radar) Doppler looks for precipitation. If you want to see an example of the weather it is tracking right now, you can see an update image here. Thanks Uncle Sam, here are my tax dollars at work.

What is so special about a Doppler Radar? I recognize the phrase but did not know what it meant. Doppler is a form of radar that can detect motions toward or away from the radar as well as the location of precipitation areas. This ability to detect motion has allows meteorologists a view inside storm systems. If they can observe rotation in the cloud, it suggests the development of tornadoes. The “Doppler effect” is the difference between the observed frequency and the emitted frequency of a wave for an observer moving relative to the source of the waves. It is commonly heard when a vehicle sounding a siren approaches, passes and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession. This variation of frequency also depends on the direction the wave source is moving with respect to the observer; it is maximum when the source is moving directly toward or away from the observer and diminishes with increasing angle between the direction of motion and the direction of the waves, until when the source is moving at right angles to the observer, there is no shift. At this point, my ability to understand the doppler effect is exhausted, to learn more about how Doppler works in this particular installation, follow this link to the National Weather Service.

In June of 2011 this outpost upgraded. It features an improvement that allows it to scan the sky vertically as well as  horizontally. This is a great place visit with your science minded kiddos. After you visit, go online to learn more about storm systems. The National Weather Service has a volunteer storm spotter and daily weather program.

How do you follow the weather?

Red Skies at Night,
Mrs. Kenney


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