The spark explained
How Lightning Works.
To start the process, electrons being to collect at the bottom of the cloud, leaving the top part of the cloud positively charged, and the bottom negatively charged. As the negative charges collect at the bottom of the cloud, negative charges in the ground repel further into the ground. This leaves the ground positively charged. The negative bottom of the cloud becomes attracted to the positively charged ground. A stream of electrons attracted by the ground. As this stream of negative charges approaches the ground, a stream of positive charges become attracted to the negative stream, and repels the positively charged ground. When the two streams connect, a down surge of electrons jump to the surface of the earth. The down surge of electrons is the lightning.
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