June 26, 2002

Chris  Doppler Makes Waves  

Lately, weather reporters on TV stations have been superimposing the name “Doppler” on the screen as they describe the weather for their viewers.  Since I do not recall ever having heard an explanation of what “Doppler” is, except that it must have something to do with weather, I felt obligated to do some research and report back to our readers.

From my high school days, I remember the Doppler Principle as causing an increase in sound as a train approached and a decrease in sound as the train disappeared from sight. We were all-familiar with that physical phenomenon and never questioned its validity because obviously it was true.

That was basic Doppler as first described 160 years ago in 1842 in relation to sound waves. Christian Doppler was born in Salzburg, Austria, in 1803.  At the University of Vienna, he studied mathematics, mechanics, magnetism, and astronomy.  This subject opened his fertile mind to the development of new and sometimes controversial ideas in these fields.

While most of his works faded into obscurity, the one and overriding successful development which has remained has been the Doppler Principle or Doppler Effect.

Starting out as a scientific observation illustrated by his depiction of the results of sound waves, the subsequent applications of his wave discovery to other important allied fields, such as radio wave technology has been extraordinary.  Weather forecasting has been a beneficiary of these new developments.

By using the Doppler Principle in radio wave technology, which is based on the speed of light, roughly 1,000 feet per microsecond, meteorologists have been given a most useful tool in predicting weather futures both immediate and days away.  They can track rainstorms, snowstorms, wind storms, hurricanes, even tornadoes. 

Doppler’s wave length description explained that sound waves were widely constructed or tightly compressed depending on distance, speed, size of object, atmospheric conditions, and other variables in order to achieve accurate results.

Other laws of physics and mathematics would also apply.  For example, since scientists know the speed of sound and of light, they can calculate the distance between the object observed and the instruments recording the event. Mountain tops and other elevated areas are preferred for better results.

With radio wave technology, or radar, rain drops, snow flakes, and wind particles can be detected and the time it takes for the radio waves to bounce or echo back gives the meteorologist information regarding the intensity of the weather pattern, including direction, elevation, and possible duration.

Local weathermen can contact the Weather Bureau office or use the computer to view constantly updated weather information and bring it to the attention of their viewers.

Some weather reporters or meteorologists; others faithfully report conditions and predictions. It is a several-times-a-day occurrence.

A newer version of weather reporting equipment and system is the Doppler Radar, which is more precise. The National Weather Service has modernized its equipment to improve the quality of its information.

By means of a cooperative effort with the Department of Defense and the Federal Aviation Administration, the Weather Service has dramatically enhanced its ability to safeguard life, property, and commerce.

Other practical uses of radar based on the Doppler Principle includes air traffic control, satellite tracking, police detection of speeding cars, military uses to locate enemy and to aim weapons, and a myriad of medical uses.

The first application many of us observed was the automatic door opener.

Even the scary sonic booms we hear from time to time are attributable to the Doppler Effect.

Hospitals and medical offices are constantly using instrumentation based on the Doppler Effect.  Many tests reveal conditions, which might otherwise go undetected.  Cardiovascular conditions are checked by Doppler tests.

It is evident that Christian Doppler could not have foreseen the tremendous benefit his sound wave discovery would have on today’s world.  I, for  one, am glad his name is flashed across the television screens as a memorial to an outstanding scientist who brought great improvement to our lives.