Studies of wind drift of charged particles in a quasi greenhouse setting

In some very large greenhouses, the spraying of insecticides is achieved by releasing uncharged fine aerosols in the air being circulated by fans. This paper presents some qualitative preliminary studies of the drift of charged aerosols. The downwind reach was evaluated by the amounts of deposits at various distances. The tests were carried out in the Boundary Layer Wind Tunnel Laboratory with real potted plants at wind speeds of 1.6 m/s and 2.5 m/s. Both charged and uncharged deposits up to 9 m downwind were estimated against the visual standards of high and low deposits. It was found that the undersurfaces of leaves were reached much more often and with greater intensify by the charged aerosol. The aerosols were observed to travel further downstream at the higher speed and considerably fewer particles were captured from the uncharged spray over the entire observing array. At 2.5 m/s wind speed, both the uncharged and charged aerosols showed substantial deposits on the tops of the leaves up to a 6 m distance. At larger distances, up to 9 m, only the charged aerosol droplets gave adequate deposits. A possible explanation is that the charged aerosol cloud, which is continually attracted to the ground by its image force, reaches lower heights in the air stream whereas the uncharged aerosols are convected at higher heights.