Airborne measurements of atmospheric electricity

An experimental investigation of the variations of atmospheric electric quantities in space and time was conducted. A review of past measurements reveals several inaccuracies and inconsistencies which stimulated the investigation. The simultaneous measurement of both polar conductivities, of potential gradient, and of several meteorological quantities from a multi-engine airplane, and the derivation of other atmospheric electric variables, are described. Altitude ‘profiles’ of conductivity and potential gradient up to 6 km obtained on a representative sounding over the Chesapeake Bay show a secondary exchange layer above the more common surface exchange layer. The space-charge density profile exhibits positive charge concentrations at the tops of these layers, near the bases of the associated temperature inversions. Upward convection of positive space charge causes the computed conduction-current density within the exchange layers to be some 40 pct higher than its relatively constant value above the layers. The product of columnar resistance and current density, employed by previous workers to obtain atmospheric potential, provides erroneous values whether the conduction current near the Earth's surface or the average value over the entire altitude range is used. On the basis of a 6-km atmospheric potential of 327 kv obtained from the integrated potential gradient, the true extrapolated total potential of the high atmosphere is 341 kv at a time near the diurnal maximum.