Instrumented Aircraft

High-performance airplanes equipped with measuring and sampling instruments are used to observe many kinds of weather and other atmospheric phenomena. "Hurricane hunter" aircraft fly into the hearts of these huge, intense weather systems. Armored research aircraft penetrate hailstorms to study the processes that produce hailstones. High-performance jets fly into plumes of smoke and ash over erupting volcanoes to sample particles that are ejected into the atmosphere, where they can affect weather and climate.

Radar

Radar-an acronym for "radio detection and ranging"-was developed to detect enemy aircraft flying under cover of clouds or darkness. The radar transmitter sends out any electronic beam that is reflected back by the metal skin of aircraft. When meteorologists discovered that water droplets in the atmosphere also reflect radar beams, radar became a valuable tool for detecting and measuring rain and other precipitation. Radar observations first identified the rainbands that spiral into the eye of a hurricane. A special kind of radar known as Doppler can measure wind speed and direction.Doppler radarhas become the best tool available for detecting tornadoes and other dangerous kinds of severe weather. It also is the key element of the new wind-shear detection and warning system that is being used at major U.S. airports. Acoustic sounders have been developed that use sound waves to measure winds in the same way that radar probes the atmosphere with an electronic beam.

Satellites

The two tools of modern meteorology that truly have revolutionized the field are satellites and computers. The first weather satellites could only provide pictures of the earth's surface and its cloud cover, not the measurements that were needed to go into computer models that were coming into widespread use in research and forecasting. Today's satellites use advanced remote-sensing techniques to measure temperature, winds, and other qualities of the atmosphere at many levels. Satellites are among the most valuable tools of meteorology because they can cover the entire surface of the earth, including vast ocean areas where no weather stations exist, and can monitor changes in global climate.

Computers

Numerical models of the atmosphere are sets of mathematical equations that represent the physical principles that govern atmospheric structure and motions. By using high-speed computers to solve the equations over and over, meteorologists can simulate days, weeks, and years of atmospheric behavior in minutes or hours, depending on the complexity of the model and the speed of the computer. The U.S. National Weather Service and most of the world's other weather services produce large-scale weather forecasts by making the weather "happen" in the computer faster than it happens in the real atmosphere. Because these simulations are so complex and use such vast quantities of data, the world' rel="nofollow"s biggest and fastest supercomputers are used in atmospheric research and large-scale weather forecasting.