METEOROLOGICAL ASPECTS OF PRECIPITATION STATIC

Abstract

Precipitation static, a result of electrification of aircraft in flight, can cause loss of radio communication for long periods of time. Electrification may consist of either of two types, ?autogenous? or ?exogenous? electrification; autogenous electrification occurs when pROLE> of snow, dust or rain strike the surface of the aircraft, while exogenous electrification results from an aircraft being placed in a pre-existing atmospheric electric field. Serious autogenous electrification occurs only in snow and dust storms; the electrification due to rain pROLE> is found to be small. Autogenous electrification is proportional to the snow density and to the cube of the air speed. Temperature, humidity, aircraft surface type, and particle size and type are found to be minor factors. Exogenous electrification was found to be accompanied by indications of convection, but no correlation data are available for the relation between the strength of the convective currents and the amount of electrification. The presence of ice crystals and water droplets coexisting in regions of highest electrification indicates that the change of state of water may be a factor in the production of electric fields in the atmosphere. The meteorological and electrical analyses of three research flights are presented.