Table I lists lightning and other storm-related fatalities by decade. Because other dangerous weather phenomenon such as tornadoes, hurricanes and flash floods often result in multiple fatalities and great destruction of property, they make headlines. Since lightning usually takes its victims one at a time, the threat of lightning is not given the attention, nor the respect, it deserves. In addition, injuries from lightning average more than 2.5 times the number of deaths from lightning, so the number of people affected by lightning every year is large. The United States has at least 100 million lightning flashes of both types every year.
Lightning occurs due to the separation of huge pools of electrical charges.
The separation in charges within the cloud is produced by rapidly rising air, called updrafts, interacting with precipitation moving downward within the cloud. The stronger the updrafts, the greater the electrical potential developed. Lightning flashes when the attraction between positive and negative charges becomes strong enough to overcome the air's high resistance to electrical flow. The entire process takes less than a second, and this is how it happens. These step leaders surge downward 150 feet at a time, sometimes more horizontally than vertically, attempting to complete a channel to the ground.