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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.
balloon-borne instrument for making atmospheric measurements, such as temperature, pressure, and humidity, and radioing the information back to a ground station. Special helium-filled meteorological balloons made of high-quality neoprene rubber are employed for elevating the radiosonde to very high altitudes of around 30,000 m (100,000 feet); maximum altitude for balloon-borne radiosondes is about 50,000 m