Lightning Development: The Positives and Negatives

Lightning filling night sky

Lightning Development: The Positives and Negatives

In thunderstorm development, the rising air called updrafts keeps various forms of frozen precipitation suspended within the cloud. Lighter ice crystals are carried upward to the top of the cloud, while heavier and denser pellets are suspended by updrafts or fall to the ground as hail.Collisions of these ice crystals and pellets become the charging mechanism needed for lightning.The ice crystals become positively charged and the pellets become negatively charged, so the top of the cloud becomes positively charged and the bottom becomes negatively charged.Meanwhile, the ground underneath the cloud becomes positively charged.

When the difference in charge gets large enough from the bottom of the cloud to the ground, asmall amount of charge (called a step leader) is sent out toward the ground. When it nears the ground, it attracts all the positive charge in the area, which start sending out small bolts of ground to air lightning (called streamers).If the streamers make contact with the step leader, a discharge occurs between the cloud and the ground and we see this as a bright flash of lightning!

thunderstorm development

Image Credit: NWS How Lightning is Created

Cloud to cloud lightning acts similar as cloud to ground, where the opposing charge builds up and requires a discharge with the negative charges in one cloud reaching out to the positive charges of another cloud (or the upper levels of the same cloud).

Updraft and Downdraft in a storm cloud

Image Credit: Weather Underground: Lightning Preparedness

April 10, 2018
Kenneth Caine
April 11, 2018
Many homes have or had lightning rods installed with the theory that the rod would hold the ground positive charge and the lightning would hit the rod and spare the house. I've also heard these never did work and perhaps actually made the house more likely to be hit. What is your thoughts on these lightning rods?
Kari Strenfel
April 11, 2018
Lightning rods are electrically bonded to the Earth via conductor and electrode, which allows electricity to pass through the building and disperse safely. They are usually mounted on the highest point of commercial buildings, skyscrapers, etc. Lightning rods aren't often added to residential homes because they aren't often the highest object in the area. If your house is on a hill, taller than nearby houses and trees, or on a large prairie or flatland AND your area is often struck by lightning, then you may consider installing lightning rods on the highest peaks/ chimneys of your house.
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