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Why Do Lightning Bolts Branch Upward From the Ground During Some Storms?
为什么某些雷暴中闪电会从地面向上分叉？
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Most lightning appears to strike downward, but it actually begins with invisible upward 'leaders' from tall objects.
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When storm clouds build negative charge, the ground below becomes positively charged by induction.
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Sharp structures like towers or trees launch positive streamers that reach up to meet descending negative leaders.
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The first connection point determines the main lightning path, which then carries massive current downward.
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High-speed cameras show upward branching occurs when multiple streamers rise simultaneously from different points.
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Tall buildings and wind turbines frequently initiate upward lightning, especially in winter storms.
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This type is more common in mountainous regions where terrain enhances electric field concentration.
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Scientists install triggered lightning towers to study upward discharges safely and repeatedly.
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Upward flashes last longer and transfer more charge than typical cloud-to-ground strikes.
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Recognizing this behavior improves lightning protection design for critical infrastructure worldwide.