Boltek EFM-100 v.2 - Manual (Page 39)

C H A P T E R 4 - O P E R A T I O N
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Figure 30: Departing Thundercloud
Figure 31: End of Storm Oscillation
Once the cloud has passed over the field will often reverse back to positive before decaying to a
normal fair-weather electric field reading of about 0.1 kV/m. This field reversal at the end of the
storm has been referred to as the “End of Storm Oscillation” (ESO).