Science on the Brunt

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Meteorology is one of the most important scientific programmes at Halley, and it has been running continuously for 60 years. One of the daily Met tasks, which the Halley Atmospheric Scientist has to do, is launching a radio sonde attached to a helium filled balloon. Every weather station participating globally in the sonde programme has to launch their balloon so that the sonde reaches the altitude equivalent to 100hPa of atmospheric pressure (roughly equivalent to 15km) at exactly 12:00 UTC (noon). The average time for the balloon to reach that altitude varies between stations, and for Halley it's just over 1 hour. The balloon will reach typically anywhere between 20 to 30 km altitude, at which it will burst and the sonde will drop back down to the ground. At that stage, the balloon can be as far as 100-150 km away from the station. During the flight, the sonde sends the data every second, and the data includes it's altitude, GPS position, atmospheric pressure, temperature and humidity. Once received by the ground station, the data is encoded into a standard message and send to the Met Office, to feed into the global weather models.