Charges imbalance in clouds causes a lightning strike.
True
The upper part of clouds, which is at a very high altitude from the surface of the earth, gets cooled to form ice. When strong winds blow, such particles exchange electrons by friction. The particles which gain electrons remain at the bottom and those which lose electrons remain at the top. In this way hundreds of coulomb charge are accumulated. Such a huge amount of charge is enough to change the air, which is an insulator, in to a conductor. Light is produced due to the flow of thousands of ampere current through air in a very short time. This is lightning. Hence the given statement is true.