Reason of lightning strike

Lightning is a natural electrical discharge that occurs during thunderstorms when electrically charged regions in the atmosphere discharge, typically between clouds or between a cloud and the ground. The primary reason for lightning strikes is the separation of electric charge within a thundercloud, leading to the buildup of strong electric fields. Here's a more detailed explanation of the process:

Formation of Thunderclouds: Thunderclouds, or cumulonimbus clouds, form when warm, moist air rises and cools, causing water vapor to condense into droplets and ice crystals. As the droplets and ice particles collide and interact, they become electrically charged.
Charge Separation: Within a thundercloud, the upper regions become positively charged, while the lower regions become negatively charged. This charge separation occurs due to the vertical movement of air and the collision of water droplets and ice crystals, which causes the lighter, positively charged particles to rise to the top of the cloud, leaving the heavier, negatively charged particles near the bottom.
Electric Field Buildup: As the charge separation intensifies, it creates strong electric fields within the cloud and between the cloud and the ground. These electric fields can reach millions of volts per meter.
Lightning Discharge: When the electric field strength becomes sufficiently high, it can overcome the insulating properties of the air, leading to a sudden discharge of electricity in the form of lightning. Lightning can occur within the cloud (intracloud lightning), between different clouds (intercloud lightning), or between a cloud and the ground (cloud-to-ground lightning).
Return Stroke: In a cloud-to-ground lightning strike, a stepped leader, which is a channel of ionized air, extends from the cloud towards the ground in a series of steps. When the stepped leader approaches the ground, a positively charged streamer rises from tall objects on the ground, such as trees, buildings, or the Earth's surface, to meet it. When the stepped leader and streamer connect, a return stroke carries a large surge of current back up to the cloud, creating the bright flash of light that we see as lightning.
Overall, lightning strikes are a result of the buildup and discharge of electric charge within thunderclouds, driven by the convective processes and interactions of water droplets and ice crystals within the atmosphere.