Most people think that lightning strikes when a stream of electrically charged particles from a storm cloud hits something on the ground. Actually that stream of charged particles shooting earthward are invisible spurts of negatively charged electricity called step leaders that travel towards the ground in search of a stream of positively charged electric particles coming up from objects on the Earth. It is only when a positively charged streamer from the Earth connects with the negative charged particles from the cloud that we see the well-known flash of light and roar of thunder as the charged particles from the Earth shoot skyward up the pathway prepared by the invisible leaders from the storm cloud. The electric current formed by the "strike" makes the air expand so rapidly that it becomes hot enough to explode and sends out shock waves that create the sound that we call thunder. One summer day as I sat in the living room of our summer house, lightning flashed and thunder roared every few seconds as a huge storm created chaos outside. Suddenly a streamer of lightning flashed past my chair, divided into two branches and then forked into several smaller branches of light before disappearing. I wonder what would have happened if one of those branches of light had hit me. Leaders known as side flashes can travel above ground from the actual lightning strike to cause injury or death, and upward leaders that do not connect with downward leaders to form a lightning strike can also carry hundreds of amps. Scary.
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