April 8, 2008
Texas

Wind farms can befuddle radar

Q. Why does the Doppler radar on KTXS always pick up the wind farm?

— Abilene

A. Let’s ask the weather guy. Damon Lane, KTXS-TV’s chief meteorologist, explained it to me.

“Radar is actually an acronym that means ‘radio detection and ranging.’ A radar impulse leaves KTXS and begins to travel through the atmosphere at a constant angle. When the beam leaves the radar, it begins to ‘listen’ for things to bump into.

“If it does ‘bump’ or ‘bounce’ off something, it sends back some noise to the radar. The louder the noise, the brighter the color on the radar map.

“If it barely hears something, then it comes back as a low noise and will usually get a green shading, which is what we get with some light rain. When it bounces off hail or heavy rain, it comes back as a bright red or yellow.

“One windmill will not put out much noise, but when you put a cluster of them together and get the blades all spinning at the same rate, then it begins to emit noise – enough that our radar can ‘hear’ the noise.”

You could tell the radar to ignore that frequency, but if there’s a thunderstorm with the same frequency, it also would be ignored.

“The use of wind energy has become a big problem not only in the meteorological world, but also to the military community as airplanes could fly low under a wind farm and one would never know the difference as to whether they are looking at false returns from the wind farm or an enemy plane.”

That’s the same answer I would have given.

By Doug “Ask Doug” Williamson