What are lightning storms?
Cumulonimbus clouds possess a strong electrical charge which varies as you move upwards through the cloud. Nearer the base, it is strongly negative, becoming strongly positive in the upper reaches. The Earth also normally has a negative charge, but during a thunderstorm this charge becomes positive. The simplest explanation for this can be found in a comparison to magnets. Since the lower portion of the cloud and the planet are both negatively charged, they repel each other, much like two magnets placed with their north poles together. As the clouds charge becomes more and more negative, so does the charge on the surface become more positive. These positive ions will then begin to move to the top of tall trees (and tall hikers on ridges) as they are attracted to the negative charge in the cloud. Because air is a very poor conductor, these ions cannot easily travel to one another. Lightning is the result of this electrical field building up to such an extent to overcome the poor conduct
