ASOS

Surface weather observations, both human and automated, provide “ground-truth” information to assist in interpreting satellite and radar information. Forecasters are able to monitor precipitation rates, temperature, pressure, and wind changes. Photograph of Automated Surface observing System (ASOS) equipment. (NOAA/NWS) -Upper right: Hygrometer, which measures humidity; barometer, which measures atmospheric pressure; and thermometer, which measures temperature. -Upper left: Transmissometer, which measures visibility. -Lower right: Anemometer, which measures wind speed and direction. -Lower left: Laser ceiliometer, which measures cloud heights and amounts.