Radar

Radar (RAdio Detection And Ranging) is an electronic detector system that measures distance or velocity by sending a signal out and receiving its return. It can pierce fog, darkness, or any atmospheric disturbance all the way to the horizon. Within its range, it can show an observer clouds, landmass, or objects such as ships, airplanes, or spacecraft. Radar can measure distance or range to a target object, and aircraft can use radar to determine altitude. Speed detection is another common application. Radar can be used to monitor atmospheric systems, to track storms, and to help predict the weather. Military applications include weapons ranging and direction, or control of guided missiles.

To understand radar, it is necessary to understand a bit about electromagnetic waves. Unlike water waves, electromagnetic waves do not require a medium to travel through. They can propagate through air, vacuum, and certain materials. Light waves, radio waves, microwaves, and radar waves are all examples of electro-magnetic waves. Just as light reflects off of some surfaces and travels through others, radar waves bounce off some objects and travel through others.