1971 Volume 49 Issue 1 Pages 32-42
Two series of experiments were carried out in purpose to discriminate the effect of the thermal conductivity of the atmosphere from the effect of vapor diffusivity on the shape of growing ice crystals from the vapor phase. In a series of experiments ice crystals were formed in helium-argon gas mixtures under conditions of a constant vapor diffusivity with varying thermal conductivities. Another series of experiments were made under conditions of a constant thermal conductivity with varying vapor diffusivities.
In each experiment ice crystals were nucleated by seeding of silver iodide smoke. In order to avoid contamination of impurity vapor, the replication technique of ice crystal was not used. Ice crystals were directly photographed from outside through a glass window placed at the bottom of a cold chamber.
It has been found that skeletal structures of ice crystals grew more significantly with increasing thermal conductivity while skeletal structures faded out with increasing vapor diffusivity.