Measuring the static electric field generated by thunderclouds the Boltek EFM-100 not only detects nearby lightning but can detect the atmospheric conditions which precede lightning. Electric field data is displayed and graphed on your desktop computer using the included software.
For complete electrical isolation from the field mill outside, the EFM-100 connects to your computer using a fiber optic cable. The EFM-100 features aluminum and stainless steel construction for corrosion resistance, gold plated connectors throughout, and the highest quality ball-bearing brushless dc motor for excellent reliability.
The electric charge contained in a thundercloud also generates an electric field. This field can be measured on the ground.
Electric fields develop wherever there is a difference in electric potential. If the electric field gets high enough you can feel your hair stand on end (if this happens outdoors during a thunderstorm crouch down with your feet together as you are about to be struck by lightning.) An electric field is what attracts your hair to a charged comb or a charged balloon.
Electric field is measured in Volts per meter (3.3 feet) The electric fields which accompany thunderstorms normally measure in the thousands of Volts per meter, usually abbreviated to kV/m.
Lightning is detected as a sudden change in the static electric field.