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RESEARCH PRODUCT

A laboratory study on the uptake of HCl, HNO3, and SO2 gas by ice crystals and the effect of these gases on the evaporation rate of the crystals

subject

description

The results of our new and earlier laboratory studies on the uptake of gases by ice crystals are summarized in terms of (1) the equilibrium phase diagram for a system gas/H2O, (2) the effect of these gases on the evaporation rate of ice crystals, and (3) in terms of the uptake of the gases by water drops. It is shown that the intrinsic quasi-liquid layer significantly affects the uptake of a gas by an ice surface in that, depending on the gas phase concentration, the layer thickness may be considerably increased by depressing the equilibrium freezing point causing additional surface melting. It is further shown that the evaporation rate of ice particles previously exposed to a gas may become significantly reduced in comparison to that of pure ice particles. Finally, it is shown that under atmospheric conditions the direct gas uptake by ice crystals may be neglected in comparison to the uptake of gases by water drops. In atmospheric clouds gases are therefore most likely taken up by ice crystals via the process of riming.