Electrostatic Force in Blowing Snow |
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| Authors: | D S Schmidt R A Schmidt J D Dent |
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| Institution: | (1) Department of Civil Engineering, Montana State University, Bozeman, Montana, 59717, U.S.A.;(2) USDA Forest Service, Rocky Mountain Research Station, 222 South 22nd Street, Laramie, Wyoming, 82070, U.S.A. |
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| Abstract: | Separation of electrostatic charge during the transport of particles by wind adds a force to the gravitational and fluid forces that determine trajectories of particles moving by saltation. Evaluating this electrostatic force requires the electric field strength very near the saltation surface, and charge-to-mass ratios for the moving particles. Field mill readings 4 cm above the surface in a moderate blizzard showed electric field strength as high as +30 kV m-1. Another experiment gave charge-to-mass ratios of individual saltation particles in low-level drifting that ranged between +72  C kg-1 and -208 C kg-1. From these measurements, we estimated electrostatic forces as large as the gravitational force on some saltating particles. Including forces of this magnitude in the equations of motion significantly alters predicted saltation trajectories from those for uncharged particles. Predictions appear reasonable that for some saltating particles, the electrostatic force prevents new surface impacts. These results should help improve models of energy transfer in the planetary boundary layer during blizzards and sandstorms. |
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| Keywords: | Blowing snow Charge-to-mass Drifting snow Electrostatic charge Electric field Saltation |
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