Till Today, Takahashi(1978) and Saunders et al.(1983) have studied riming electrification in cold room experiments simulating thunderstorm conditions, but the results they got were very different from each other.
Now, we succeeded in floating an ice hemisphere in the wind tunnel. We measured only the sign of the charge with induction rings in the regions where their results are very different from each other.
When both ice crystals and supercooled droplets were supplied, high electric charge occured on riming ice hemispheres. Atabout -15℃, the ice hemisphere charged positively with lower cloud water contents, while the ice hemisphere charged negatively with higher cloud water contents.And also at about -5℃ with higher cloud water contents, the ice hemisphere charged positively.
The results we could get in this exeperiment support Takahashi(1978)