Initial balloon soundings of the electric field in winter nimbostratus clouds in the USA

Presented are the first known vertical profiles of electric field, E, in six winter nimbostratus clouds in the USA. No lightning was detected while the E profiles were collected. Deep convection was embedded in one of the clouds that had been a thunderstorm. The maximum magnitude of the vertical component of the electric field, E z , in the profiles ranged from 1 to 12 kV m −1 ; the maximum horizontal component ranged from 0.2 to 28 kV m −1 . The latter indicates that the charge in the cloud was not horizontally homogeneous. The E z versus altitude profiles have 1–3 peaks inside the clouds. From the profiles, we inferred up to four charge regions stacked vertically. Peaks in E z are found in regions of melting as evidenced by radar bright bands: Both polarities of charge are inferred in the bright bands. Three nimbostratus clouds without melting precipitation also were electrified.