Positive vs negative lightning: What's the difference? - WNEM TV 5

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Positive vs negative lightning: What's the difference?

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Storms that passed through the state last evening featured some incredible lightning shows. 

When tracking storms on radar, we're able to get a count of the lightning strikes occurring with the storms that are passing through. In events were there are tremendous amounts of lightning, we usually show the lightning counter on your screen.

And while it's easy to understand the total number of strikes, we often get the question: "What is the difference between positive and negative lightning strikes?".

We received that question again last evening, so we decided to break it down for you with some facts and information from the National Weather Service. 

Let's Start With The Negative

When positive and electrical charges within thunderstorm clouds start to separate, an electrical field develops with negative charges at the cloud base and positive charges at the top. Eventually, when the charge builds up enough, lightning occurs. 

Not only does an electrical field develop in the cloud, but a positive field near the ground develops too. When charges continue to build up, these positive charges near the ground start rising to taller objects. 

A negatively charged channel, a stepped leader, travels from the bottom of the cloud to the ground as the charge builds up. The positive charge at the ground creates it's own channel called a streamer, and once the channels connect, we get cloud-to-ground lightning. 

This lightning is referred to as a negative strike as the negative charge is transferred from the cloud to the ground. Negative lightning strikes carry around 300 million volts and 30,000 amps of power while also reaching 50,000 degrees Fahrenheit.

Now To The Positive

While most lightning is negatively charged, around 95%, that's not always the case. 

On occasion, lightning originates near the top of the cloud, where the positive charges are found. In this situation, the lightning follows the same process as the negatively charged strikes, but the descending stepped leader will be positive with the upward streamer channel will have a negative charge. 

With the positive transfer to the ground, these strikes are called positive lightning strikes. 

Although positive lightning strikes occur far less than negative strikes, it can be more dangerous. 

Since the strikes originate in the upper parts of the storm, they must travel a greater distance, therefore the electric fields associated with these strikes are usually much stronger. As mentioned above, negative strikes have nearly 300 million volts, but positive strikes may have as much as one billion volts, along with 300,000 amps. 

With their additional strength, positively charged strikes are believed to be responsible for a large percentage of forest fires and damage to power lines. 

Some positive strikes can also be dangerous because they can occur near the edge of the cloud or from the anvil top of the thunderstorm, which can occur from more than 25 miles away from any rain. 

That fact is a great reminder that when thunder roars, we need to go indoors. If you're close enough to hear the thunder, you're close enough to be struck by lightning. 


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