Weather Whys; Radar

This is weather-wise. Radar was developed during World War II for the purpose of tracking enemy planes, but Radar operators noticed that storms also showed up on their screens. So as a side effect of Radar's development, the science of meteorology moved into a new era. Using Radar, scientists were able to peer inside clouds and storms to get new information on their inner workings and to find areas of precipitation without an eyewitness sighting. The era of remote sensing had begun. The acronym Radar is short for radio detection and ranging. A radar unit sends out or transmits pulses of microwave energy. When that energy hits an area of rainfall, some of it will be reflected toward the transmitter. The reflected energy is known as the radar return, and it's detected by a device called the receiver. The delay between the time the pulse is transmitted and the time the reflection is received determines the distance between the radar and the rain shaft.

The strength of the return shows how heavy the rain is. Computers often convert radar returns into various colors so the areas of heavy and light rain are more easily visible. Generally, the lightest rain is shown in greens, with yellows for more moderate precipitation and oranges and reds to represent the heaviest rain. But while radar energy is reflected by tiny raindrops, it's also reflected by larger things, such as buildings and mountains. In fact, there's almost always some energy reflected by nearby objects and sometimes even by the ground. That shows up on a radar screen as ground clutter, which usually appears as an irregular shaped area near the center of the screen. However, some of the newest radar units are able to use computer technology to remove those images and give scientists a better view of the rain. And for weather wise, I'm Drew Barlow.