Abstract:
An electrostatic field mill, operated by the University of Auckand Physics Department was installed at Vanda Station and monitored electrical fields during storms throughout the year over several seasons. A phenomenon was recorded in April 1970 and considered at the time to be caused by blowing snow. The sensitivity of the mill was such that it had a full scale chart deflection of 800 volts per
... metre. During these storms, the mill was often observed to be indicating a positive field well beyond full scale deflection. Antenna coaxial cables inside the laboratory were arcing vigorously, sometimes continuing to do so for quite some time after a lull in the wind. On one particular occasion, arcing was observed during dead calm for up to 20 seconds after the wind had dropped. This indicates the probability that large DC fields were being induced, remaining present after the removal of their cause until their eventual discharge. It was eventually realised that the phenomena was brought about by blowing dust, and not blowing snow as originally thought. A device for trapping blowing dust at various heights above ground was constructed and installed during July 1970 and the various densities of the samples were reported. Dust samples were sent to the University of Auckland. The interference due to the effects of wind borne electrified dust was investigated. An instrumentation system was set up to collect the dust and record its electrical effects during storms, a dust impactor was installed for collecting and automatically grading dust on charts, a field mill was maintained for measuring atmospheric electric fields during storms, a multichannel radio receiver for monitoring radio interference of electrified dust was installed and a ten channel data logger was installed for recording wind speed, atmospheric field and radio interference. Glass plates were also mounted facing North, South, East and West, on a rock dyke 200 yards south of the laboratory at a height of 0.5m off the ground to provide information on the abrasive effect of the windblown sand in this area. 
