Lightning Strikes!

Lightning Strikes!

23 August, 2016
Lightning FAQs
Curious about Hong Kong’s lightning spectacle last month? We’ve got the answers to your questions.
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Last month, Hong Kong was hit by an incredible 10,000 bolts of lightning during an impressive 12-hour long thunderstorm.

The Hong Kong Observatory raised the thunderstorm warning at 6:45pm on 9 July, only hours after the city was recovering from the hottest July day in half a century.

But what was it that caused all the lightning to occur in the first place? The answer is hinted at in the paragraph above- it was because of the abnormally hot weather.

When the air is hot, it rises, and then condenses to form a cloud. As air continues to rise, the cloud grows bigger and bigger. At the top of the cloud, the temperature is below freezing, and so this water vapour turns into to ice.

As more and more ice is formed, the ice starts to bump into each other and this creates a build up of electric charge. After a while, the top of the cloud is predominantly made of lighter, positively charged particles, and the heavier, negatively charged particles sink to the bottom of the cloud.

When these positive and negative charges grow great enough, a gigantic spark is emitted between the two charges, creating lightning!

Different types of lighting
There are two main categories of lightning, cloud-to-air lightning (CA) and cloud-to-ground lightning (CG). The first type appears as ‘flashes’ in the clouds; it’s lightning that doesn’t touch the ground. On average, CA lightning occurs 5-10 times more often than CG lightning. The second type is the stereotypical type of lightning that comes to mind; it’s the forked pattern that zigzags downwards to strike the ground.

What is a dry thunderstorm?
A dry thunderstorm is one that produces thunder and lightning, but doesn’t produce any rain. This is because all the rain is evaporated before it reaches the ground. During these conditions, our country parks are at the greatest risk of a wildfire being triggered by lightning, so you should pay attention to park and HKO weather warnings!

Can lightning strike the same spot twice?
Yes! Contrary to the saying ‘lightning never strikes twice’, lightning can indeed strike the ground at the same location twice. It has a statistically lower probability that it’ll strike the same place twice however. Also, objects that are taller are more likely to be struck, as they are closer to the thundercloud.

Am I safe at home?
Yes! All buildings under Hong Kong law have a lightning rod/conductor at the top of the building. The rod attracts electric charges and leads it safely down the building via an earthing device. This protects you and your building from lightning!

Where can I get more information about lightning?
All information about thunderstorm and lightning warnings in Hong Kong can be found at the amazing HKO website: click here

Otherwise, for more FAQs on lightning, the National Severe Storms Laboratory page has fantastic educational materials on lightning: click here

By: Ecozine Staff
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