Electric charge separation during the fragmentation of rime in an airflow

Abstract Experimental evidence is presented to show that when fragments of rime break off a simulated graupel particle in an airflow, significant magnitudes of electric charge are separated only under very specific conditions. Subsidiary experiments indicate that the charging is more likely to occur when the broken fragment makes contact with the graupel particle as it is swept away in the airflow and not during the breaking process itself. The relevance of this process to the interpretation of results of laboratory studies of thunderstorm electrification is discussed, and it is shown that the positive charging of graupel observed by various workers cannot be due to rime fragmentation as has been proposed.