Wind Measurements from Hot-air Balloon flights

Trajectories from commercial hot-air balloon flights can provide interesting wind information in the lower atmosphere. The displacement of a hot air balloon is closely related to the wind speed and direction and thus a potential source for wind observations in the atmospheric boundary layer. This part of the atmosphere is not frequently sampled, apart from radiosonde launches and measurements taken at atmospheric remote sensing sites and airports. In order to facilitate the collection of the data from hot-air balloons we have developed an app for smart-phones and we show the first results.

In this presentation we discuss the response time of the balloon on a step wise changing wind and we have found a response length which is proportional to the dimensions of the balloon. The hot-air balloon flights contain interesting meteorological phenomena. Baroclinic effects like the turning of wind with height due to a horizontal temperature gradient are found in the balloon tracks. Also smaller scale phenomena like low level jets and sudden wind jumps are shown. We compare the hot-air balloon data with other wind observations and NWP output.