The Variation of the Electric Field of the Atmosphere caused by the Dust Storms

[摘要] In Winter the dust storms occur frequently at Honjo and they disturb the electric field of the atmosphere. At the Honjo Observatory the Bendorf's Electrometer has been set since November 1948, and we obtained many interesting records of dust storms. From November 1948 to April 1949 we observed the dust storms 7 times, and two of them caused the variation of positive potential gradient and others negative. The maximum departures of the potential gradient were 3500 V/m and -2600V/m.When the dust storms do not occur at the station and they occur at distant places or we can find them nowhere, the electrometer records the disturbance of the potential gradient in windy days. Its characteristics resemble the variation caused by the dust storms.We also observed the space charge of the atmosphere. The instrument is wire-netting cube and at the centre of this cube polonium collector is supported. The collector is connected to the leaf electrometer. When the potential gradient is positive (or negative) at the dust storms, the space charge is also positive (or negative). The value. of the space charge in the dust storms is 8 times as large as that of the calm days.We made further an experiment on the charge of the dust particles. We used three kinds of sand or soil. The result of the experiment shows that the larger particles have positive charge and smaller particles have negative charge by the friction between dust particles.

[学科分类] 大气科学