Wednesday, April 29, 2009

Doppler Detected Speeders!


There's some good radar refraction taking place from the Memphis radar site this evening. Meteorologist Phil Baker at the NWS pointed it out to me and I captured some images on StormTRACK Doppler 8. Look at the "blips" just north of Blytheville on I-55. That's not rain. That's traffic!

Radar does not operate like a laser beam in a straight line, but it bends vertically and horizontally and speeds up and down in response to the atmospheric conditions. (I believe the air density is the main driver to this phenomenon.) When the wavelength is slower in spots, it tends to bend toward the slower portion of the wave. This is called refraction. When it does this, you can occationally see traffic on the interstate!

The second image below shows the "velocity scope". we typically use it to detect rotation. If you notice the bright pink areas, that's the traffic. Phil says he clocked some people going 82 mph... LOL I wonder if the NWS can write tickets? :)



Pretty cool huh?
Ryan

3 comments:

Anonymous said...

Oh Oh.................speeders prob have no ideal this can be done............and No, you are not the only human that does not watch Idol!

Karen H. said...

Oh Wow, this is so neat. I wonder if the Police Departments are aware of this? Maybe they should start using it and catch some of those speeders out there. On Tuesday afternoon after the rain had finally ended we ended up with 5 inches of rain here in Caraway. Yesterday afternoon we got another 1/2 inch of rain, so that is 5.5 inches of rain here in Eastern Craighead County. Know where I can buy some cheap lumber? LOL. May have to get busy building me an ark before too long. LOL. Take care and have a great Thursday.
Karen Horton
Caraway, AR

MWN/Erik said...

Great post, Ryan. Looks like you and Phil have found the next "remote" radar gun. Speed traps could be set up anywhere! Of course, the Doppler principle itself is the basis for detecting speeders in the more traditional manner too!

--Erik, MemphisWeather.net