Scattered thunderstorms will remain in the forecast for at least another day as a weak low pressure center slides down the Sacramento Valley, adding just enough dynamics to daytime heating to stir things up in the afternoon. The low moves away Friday which should allow clearing conditions across the area which will stick around through Saturday. A slight chance of afternoon thundershowers comes back into the region Sunday and Monday.


View of intercloud lightning at night, late Twentieth Century. (Photo by Hulton Archive/Getty Images)

So what is the difference between lightning that is cloud to cloud vs cloud to ground? What occurs in both cases is the vertical motion of the strong updrafts creates a separation of electrical charges…. Positive on the tops of the clouds, and negative on the bottom. Envision a giant Duracell Battery and you’ll get the general idea. On a cloud to ground strike, the negative charge on the bottom of the cloud induces a positive charge on the ground, and since nature abhors big imbalances like that, there is a discharge to neutralize the electrical potential. The cloud to cloud does essentially the same thing, but the negative bottom of one cloud discharges into the positive top of another.

lightning diagram