Observations on the directions of current from earth to air have shown that up to July 1 there was little or no loss of negative charge. The weather from July 1 to September 15 was generally fair and during most of this period there was a very small loss of negative charge. At no time between September 15 and March 28 has there been any indication that the earth was losing negative charge, although there have been many days which would be classed as fair weather.
Proceedings of the Iowa Academy of Science
©1932 Iowa Academy of Science, Inc.
Butler, L. W. and Dorchester, C. S.
"A Note on Atmospheric Electricity and the Effect of Electricity on the Growth of Plants,"
Proceedings of the Iowa Academy of Science, 39(1), 218-218.
Available at: https://scholarworks.uni.edu/pias/vol39/iss1/58