A balloon-carried electrometer for high-resolution atmospheric electric field measurements in clouds

A disposable sensor for electric field measurements within clouds is described, which operates in conjunction with a standard meteorological radiosonde carried beneath a helium balloon. The radiosonde supplies telemetry and meteorological data. The sensor is constructed to measure electric fields of order 100 V ${\mathrm{m}}^{\text{−1}}$ and has been calibrated to 400 V ${\mathrm{m}}^{\text{−1}},$ typical of weakly electrified nonthunderstorm clouds. It measures using a regular cycle of measurement, dynamic zeroing, and marker pulses, which permits the integrity of the received data to be assessed. The electric field sensor is optically connected to the radiosonde, allowing it to remain electrically floating from the balloon system. A low-leakage electrometer switch for dynamic zeroing is an integral part of the system, and successful electric field measurements have been obtained aloft in temperatures down to $\text{−60\hspace{0.05em}°}\mathrm{C}.$