According to the National Severe Storm Laboratory, a single lightning bolt can have 100 million to 1 billion volts, and it contains billions of watts, depending on whether it is positive lightning or negative lightning. Lightning strikes ground in the United States approximately 25 million times each year.
Positive lightning, which comprises less than 5 percent of all lightning, originates on top of the clouds, rather than the lower portion of the storm, as negative lightning. These type of lightning can travel up to 25 miles horizontally in the air before they strike the ground and are sometimes called "bolts from the blue." Because of the greater distance to the ground, they develop much higher voltages.