Gerdien Probe
Gerdien Conductivity Probe

The Gerdien Conductivity Probe was designed to measure the atmospheric electrical conductivity. In order to determine the conductivity, a sample of air is exposed to a capacitor and the time taken to discharge is measured. The Gerdien Probe can detect both the positive and negative ion conductivity. The conductivity of ions is determined by supplying a voltage between two electrodes over a period of one minute and measuring the resulting current. The rate of change of the current with respect to voltage provides a measure of conductivity. Additionally, special considerations were taken in construction to reduce the influence of electromagnetic interference and current leakage.