The accumulation of electric charges must be great enough to overcome the insulating properties of the air. Lightning happens when the negative charges (electrons) in the bottom of the cloud are attracted to the positive charges (protons) in the ground. This is because light travels much faster than sound. Thunder and lightning occur at roughly the same time although you see the flash of lightning before you hear the thunder. We see it as the bright flash of a lightning bolt. This electric current is known as the return stroke. When the stepped leader and the positive charge meet, a strong electric current carries positive charge up into the cloud. The positive charges at the ground are attracted to the stepped leader, so positive charge flows upward from the ground. Once the negative charge at the bottom of the cloud gets large enough, a flow of negative charge called a stepped leader rushes toward the Earth. How Is a Lightning Bolt Formed?īecause opposites attract, the negative charge at the bottom of the storm cloud wants to link up with the ground’s positive charge. The top of the cloud becomes positively charged with particles called protons, while the base of the cloud becomes negatively charged. This separates the positive (+) and negative (-) charges of the cloud. Small negatively charged particles called electrons are knocked off some ice crystals and added to other ice crystals as they crash past each other. What's Happening Within the Cloud?Īs ice crystals high within a thunderstorm flow up and down in the turbulent air, they crash into each other. The expansion creates a shock wave that turns into a booming sound wave, known as thunder. A single stroke of lightning can heat the air around it to 30,000☌ (54,000☏)! This extreme heating causes the air to expand explosively fast. But wait a minute, what does thunder have to do with lightning? Well, lightning causes thunder. In fact it is how thunderstorms got their name. Lightning is the most spectacular element of a thunderstorm. Lightning is a very strong jolt of electricity, creating glowing gas particles called plasma that light up the night sky.

Lightning strike