Estimation of the electrostatic charge of individual blowing-snow particles by wind tunnel experiment

Abstract

There are some reports on the measurement of the charge-to-mass ratio of blowing-snow particles, but there are few studies concerned with individual snow-particle charge. We measured the charge-to-mass ratios using snow particles selected according to size, and discussed individual charges. Experiments were conducted in a cryogenic wind tunnel. Charge-to-mass ratios measured in our experiment were all negative and their absolute values tended to increase with a decrease in particle diameter. Individual snow-particle charges were calculated from the average of particle diameter distributions. The charges were all approximated by the power function of diameter at each temperature. Assuming that the coefficient of these approximations is a function of air temperature, we could easily predict the individual snow-particle charge.

Idealized Study of a Static Electrical Field on Charged Saltating Snow Particles

“…negatively and positively charged particles. Note that we expect from measurements that particles are on average negatively charged (Omiya et al, 2011).…”

“…Based on the facts that the charge carried by particles tends to be saturated during the process of particle-particle and particle-surface collisions (Yu et al, 2017) and the mid-air collision between snow particles is at low probability (Schmidt, 1972;Sommerfeld and Zivkovic, 1992). We therefore assume saturated charges for our particles, and with the values estimated in the wind tunnel experiments (Omiya et al, 2011) which are relatively small limited by the total length of system. E(z) is the electric field at the height of z, which can be calculated as the following empirical formula for moderate drifting snow electric field from Schmidt and Dent (1994):…”

“…The polarity of charges obtained on a snow particle surface is either positive or negative (Kikuchi, 1981;Maeno et al, 1985), and the value of its charge is between −208 μC/kg to +72 μC/kg (Schmidt et al, 1999). Most of the snow particles in the air have a negative charge, and the bed has a positive charge (Omiya et al, 2011). This distribution pattern of charged particles leads to a positive upward electric field in the reverse direction of the atmospheric electric field.…”

“…For example, it blocks the radio signals of airplanes passing through a snowstorm (Simpson, 1919;Currie and Pearce, 1949;Yair et al, 2019). Besides, some studies suggest that the snow cornices formation mechanism may be related to the strong electric field at the mountain ridge (Latham and Montagne, 1970;Omiya et al, 2011).…”