Abstract: A system for investigating the variation of one or more wind characteristics within a volume over a given area comprises a plurality of detectors which output a data signal which is indicative of the value of a wind characteristic, the outputs of all the detectors deployed in the area are relayed to a central receiving unit which may include a recorder for recording the relayed data and may additionally provide a computer and a VDU for providing a real-time display of the data. Preferably each detector comprises a balloon or kite-like device each of which is tethered to one of a plurality of anchor points distributed around the area.