Our atmosphere is electrified at all times. During the summer the average increase of potential from the earth's surface up is about 100 volts for one meter of ascent. This potential gradient, however, diminishes with increasing altitude until at the height of one mile it is only 25 volts per meter. During the winter the atmosphere is much more in tensely electrified. The average increase of electrical potential near the earth 's surface during this season is as much as 250 volts per meter of ascent.
©1931 by Iowa State Teachers College
"About Atmospheric Electricity,"
Science Bulletin: Vol. 3:
5, Article 3.
Available at: https://scholarworks.uni.edu/science_bulletin/vol3/iss5/3