Weather and Storm Detection

Doppler radar tower

Source: Doppler-Radar-Tower, Intersofia, Wikimedia Commons

Doppler radar image

Source: Hurricane Katrina Doppler, National Oceanic and Atmospheric Administration, Wikimedia Commons

You may have heard the weather reporter refer to her radar as a Doppler radar.

Meteorologists use the Doppler radar to make very precise measurements of the magnitude and direction of a storm's velocity. Therefore, they can make better predictions of where a storm is heading and when it will get there.

Video segment. Assistance may be required. Watch this quick video to see how it works.

Source: How does a weather radar work?, JoCoEmergencyMgmt, YouTube


Waves can also be Doppler shifted when they reflect off of a moving object. The motion of the object from which they echo shifts the frequency of the reflected wave. Bats and dolphins use this principle to locate and hunt for food. They use a process called echolocation, which involves the emission of a sound wave to locate prey by listening for its echo. A bat's ears are so sensitive that they can tell the size, location, direction, and speed of an insect as small as a gnat from the Doppler shift.

bat locating an insect by listening to reflected sound wave

Source: Bat echolocation, Shung, Wikimedia commons

Traffic Applications

The Doppler shifting of reflected radar waves is an accurate method for determining the speed of objects. Police officers use a radar gun to determine a driver's speed and decide whether a ticket is warranted. The gun does a quick calculation of your speed by determining the frequency shift of a radar pulse.

radar gun commonly used to catch speeders

Source: USSR Radar gun 65, Sergeev Pavel Wikimedia Commons

In summary, you investigated the Doppler effect and saw how it connects you to motorcycle police, bats, and the weather reporter.