Sublimation in a Wilson Chamber

Abstract

As a result of some experiments on the deposition of water vapour at low temperatures, it was found that the liquid phase can frequently exist much further below the freezing-point than was expected. For example, droplets of super-cooled water can be obtained at – 50° C. without difficulty. It appeared also that the number of nuclei in atmospheric air on which water vapour could form ice crystals without the previous formation of droplets was small, and they appear to be active only below about – 40° C. Arrangements were therefore made to repeat Prof. C. T. R. Wilson's classical experiments below the freezing-point, both in thoroughly clean air and in ordinary atmospheric air. The following results were obtained: