Does lightning come only from clouds?
Photo: Flickr user ReutC
Where does lightning come from?
Lightning can originate in sandstorms or erupting volcanoes, but most lightning comes from rainclouds.
Clouds are turbulent mixtures of ice crystals, water droplets, and the icy seeds of hailstones. When an ice crystal hits the seed of a hailstone, the stage is set for lightning. During such collisions, the hailstone seed often ends up with a negative electrical charge, while the ice crystals get a positive charge. Positive and negative electrical forces attract, but the ice crystals make a quick getaway – they’re very light, so they tend to float up to the top of a cloud. The heavier hail seeds hover around the cloud’s middle. Later, if these icy seeds and ice crystals get close enough, they’ll reach out and try to balance each other with a flash of electricity – a lightning bolt inside the cloud.
Now consider a very tall cloud. The ground might be closer to the cloud’s mid-level hailstone seeds than the seeds are to the ice crystals in the cloudtops. Then the negative charge of the seeds attracts a positive charge from the ground – again creating lightning!
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