how the how the doppler effect could be used to warn aginst an oncoming tornado?

Question

tornadoes can develope in only an hour and they can cause much demages in only a fewminutes describe how the doppler effect could be used to warn aginst an oncoming tornado

Answer 1

Doppler radar (commonly used by TV weather guessers) is able to pick up things in motion. Tornadoes and other weather phenomena (like rain squalls) are certainly in motion.

The Doppler effect is that apparent raising of a frequency from a body approaching the observer and the apparent lowering of a frequency from a body leaving the observer. If we have a base frequency (f0) transmitted from a radar, the echo frequency from a moving object would be fa > f0 for an approaching target (e.g., tornado) and fd < f0 for a leaving target.

Doppler radars are designed to display these differences in base frequency and the echo frequency. Needless to say, but I'll say it anyway, the greater the frequency differences, the easier it is for the Doppler radars to display the moving targets. In fact, if the frequency differences are color coded, which they usually are on TV, we can see levels of severity (e.g., green for not much up to red for real severe weather).

Points of clarification...Doppler radars do not pick up winds; what they pick up are the stuff in the winds, like water droplets. So called clear air shears, for example, do not show up on Doppler radars, which is why they are so dangerous to commerical airlines. Radar does not bounce off gases (plasma excepted), solids (like water) are needed.

Second, a rain squall or tornado does not need to be moving laterally across the ground to be detected by Doppler radar. It suffices to have rain falling or debris blowing to create the frequency differences needed for detection.

Answer 2

how the how?? What does that mean? Doppler radar measures the wind speed differential from both sides of an approaching storm. The speed and pressure differences can then be analysed to determine if a tornado has formed.