Effect of wind on surface hoar growth on snow

Field observations of surface boar formation were carried out with the measurements of water vapor condensation rate, snow surface temperature, air temperature, humidity, wind speed, and net radiation. Large surface boar crystals were observed to form under the breezy wind, 1 to 2 m s(-1) at 0.1 m high. The condensation rate increased linearly with the product of the vapor pressure gradient and the wind speed. The bulk transfer coefficient of water vapor C-e was roughly constant when the surface boar crystals were small, whereas it showed some increase as the boar crystals grew to several millimeters in height. A Possible cause of this increase in C-e is that the developed surface boar crystals modify the aerodynamic roughness and consequently increase the turbulent transfer of water vapor.