On the Polarity of the Electric Charges on snow Crystals of the Various Shapes

Abstract

Some observations in the field of cloud physics and atmospheric electricity were carried out when the author was a member of the wintering party of the 9th Japanese Antarctic Research Expedition at Syowa Station, Antarctica throughout the whole year from February 1968 to January 1969. Especially, a simultaneous observation of electric charges on natural falling snow crystals, the shapes of snow crystals and electric field strength were selected from a view point of importance and interest of the charge generation in clouds.As a result, a very interesting phenomenon was found in which the electric polarity of snow crystals of dendrite, sector and plate was negative and the polarity of snow crystals of column, combination of bullets and side plane was positive. Taking into account that the temperature range of the growth of dendrite, sector and plate is roughly between -10* and -20* and that of the other three shapes of snow crystals are between -20* and -35*, it would be appropriate to assume a positive polarity of a thundercloud and other electrified clouds with solid precipitation particles. In other words, it may be considered that negative and positive charge centers in the cloud volume are located around the -15* level and the -25* to -35* level, respectively.These temperature ranges coincide with Takahashi's observation (1965) using an electric charge sonde, in which he reported that positive charged particles were observed at a temperature range between -18* and -39* and negative charged particles were present at a range between 0* and -18*.

The Electrical Structure of Snow Clouds, Part II, Vertical Distribution of Precipitation Charge

“…Magono and Orikasa (1966) reported a case in which negatively charged snow crystals continued to fall for a long period under steadily positive fields on the ground. Such conditions, although they existed for a short period, were confirmed by other researchers, Nakaya (1954), Isono et al (1966) and Kikuchi (1973). The electrical structure of a stratiform snow cloud on March 1, (Fig.…”

The Electric Charge on Individual Ice Crystals (Snow Crystals in the Early Stage)

“…Shio (1968) found that the sign of frictional electrification of the basal plane of ice is different from that of the prism plane. It is, therefore, interesting that snow crystals of column type or side plane type were mostly charged positively, as found at Syowa Base, Antarctica by Kikuchi (1973). However, the result of the present measurement did not agree with that of Kikuchi in the sign of charge, although the number of measured ice crystals were not sufficiently large in the present work.…”

“…3, however it appears that the charges on columnar type ice crystals are large for their sizes, compared with that of plane type ice crystals. It is also noted that the number of negative ice crystals are larger than positive ones, against the result of Kikuchi (1973), although the number of measured ice crystals in the present work was insufficient.…”

“…And Kikuchi (1973) reported that snow crystals of column, bullet and side plane type were mostly charged positively.…”

Airborne biological particles and electric fields

“…The focus of this paper is on the observed relations between electric field measurements and the deposition of snow crystals and airborne dust. Strong electric field gradients in polar climates with high winds have been described for various regions and under various environmental conditions [e.g., Cobb, 1977;Herman, 1965;Kikuchi, 1973;Koenigsfeld and van der Schueren, 1965;Wishart and Radok, 1967]. As far as we know, attention has not been given previously to relations between electric fields and airborne particles, except in connection with the applications of electrostatic principles to dust removal or aerosol spray control.…”