how do clouds get electrically charged ?

Hi Harsh!

Water from the sea and other sources evaporates and drifts upward due to the low density of the vapor, and forms clouds. During the upward journey, they acquire electric charge due to friction. These charges are accumulated in such a manner that the positive charges are accumulated on top of the cloud and negative charges are accumulated on the bottom. The air is an insulator of electricity. When two clouds come near, or the potential difference between the cloud and the ground is too high, then the air between the clouds or between the cloud and ground undergoes dielectric breakdown and conducts electricity. This flow of electricity is known as lightning.

Cheers!!