Doppler Radar

http://www.stuffintheair.com/Doppler-radar-weather.html

The above illustration is an example of the Doppler radar system which we use today and is typically used by weather forecasters to show the location and velocity of different storms, clouds, and precipitation that form across the globe.  Doppler is used to show different phenomenon across the globe at a distance and allows us to prepare for them ahead of time and hopefully before they hit land.  Above shows the velocity of a windstorm over Canada and the different colors are used to help understand the magnitude/speed of the winds.