Lightning is caused by the buildup and discharge of electrical charges within and between clouds during thunderstorms. The movement of air currents and ice crystals within the cloud, along with collisions between these particles, separates positive and negative charges. When the electric potential between these charged regions becomes strong enough, a massive discharge occurs, resulting in the bright flash and sound of lightning.
Here’s a more detailed explanation:
1. Charge Separation:
During a thunderstorm, vigorous air currents cause ice crystals and water droplets to collide within the cloud. These collisions lead to the separation of electrical charges. Lighter, positively charged ice crystals tend to move upward, while heavier, negatively charged hail particles move downward. This movement creates a separation of charges within the cloud.
2. Charge Buildup:
As the storm develops, more and more charges separate and accumulate within the cloud. The upper part of the cloud tends to become positively charged, while the middle and lower parts become negatively charged. A positive charge also develops near the base of the cloud.
3. Electric Potential:
The separation of these charges creates a large electric potential difference between the cloud and the ground, as well as between different regions within the cloud.
4. Discharge:
When the electric potential difference becomes strong enough to overcome the resistance of the air, a massive electrical discharge occurs. This discharge, known as lightning, can happen within the cloud (intracloud lightning), between different clouds (cloud-to-cloud lightning), or between the cloud and the ground (cloud-to-ground lightning).
5. Lightning Bolt:
The discharge creates a channel of ionized air, allowing the flow of electricity. This channel is incredibly hot and bright, producing the visible flash of lightning. The rapid heating and cooling of the air surrounding the lightning channel creates a pressure wave, which we hear as thunder.