charge separation

The physical process causing cloud electrification.

On the particle scale, the process can include particle collisions with selective charge transfer and particle capture of small ions. On the cloud scale, the process can include gravity-driven differential particle motions and convective transport of charged air parcels.

1. Regular markings on an instrument used to allow the reading of the measured quantity or setting.

An aggregation of sufficiently many atoms or molecules that it can be assigned macroscopic properties such as volume, density, pressure, and temperature.