The Doppler radar eventually would allow forecasters and researchers to see inside the clouds. The concept was developed by Christian Andreas Doppler based on sound waves. Doppler noticed that a train whistle becomes higher-pitched as it nears and lower-pitched as it passes by. The nineteenth-century Doppler effect was adapted to twentieth-century radar use. A Doppler radar could determine the intensity and direction of the winds and rain. Modified for thunderstorms, it could allow forecasters to see the telltale signs of rotation from the mesocyclone.
