A radiosonde (Sonde is French for probe) is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz and both types may be adjusted slightly higher or lower as required.  They measaure Pressure, Altitude, Geographical position (Latitude/Longitude), Temperature, Relative humidity, Wind (both wind speed and wind direction) and Cosmic ray readings at high altitude.

Twice daily at 0:00 and 12:00 GMT these radiosondes are deployed from Edmonton.  The SKEW-T diagram below shows a vertical look at the winds, pressures, etc above us. for More info on How to Read a Skew T click here