Skip to content
Know.itKnow.it
Create an animated lesson
On request

This article is free to read. Creating a lesson uses your daily or stored credits; review the language and settings before starting.

What is lightning?

ScienceLesson on requestFree to read

Quick answer

Lightning is a sudden, powerful spark of electricity that jumps between a cloud and the ground, or within a cloud. It happens when electric charge builds up inside a storm cloud until it discharges in a brilliant flash, heating the air to many times hotter than the Sun's surface.

Key things to understand

  1. Inside a storm cloud, colliding ice and water particles separate electric charge — lighter positive charge near the top, heavier negative charge near the bottom.
  2. When the charge difference grows strong enough to overcome the air's resistance, a massive spark — lightning — leaps to balance it.
  3. A lightning bolt heats the surrounding air to about 30,000°C, roughly five times hotter than the Sun's surface.
  4. That sudden heating makes the air expand explosively, which we hear as thunder.
  5. Lightning can strike cloud-to-ground, cloud-to-cloud, or within a single cloud.

People also ask

What causes lightning?
A build-up of electric charge inside a storm cloud. When the difference between positive and negative charges becomes large enough, it discharges as a giant spark — lightning — to balance out.
Why do we see lightning before hearing thunder?
Light travels far faster than sound. The flash reaches you almost instantly, while the thunder it creates takes about 3 seconds to travel each kilometre.
Is lightning hotter than the Sun?
The lightning channel itself can reach about 30,000°C — around five times hotter than the Sun's visible surface — but only for a tiny fraction of a second.