|radiosonde (rā'dē-ō-sŏnd') Pronunciation Key
An instrument that is carried into the atmosphere by a balloon, makes measurements of temperature, air pressure, humidity, and wind speed and direction, and transmits the measurements back to the ground. A radiosonde is typically sent to altitudes of approximately 30 km (18.6 mi). There are approximately 70 radiosonde stations across the continental United States. Each station launches two radiosondes daily.