The Story of Lightning
When water evaporates from the surface of earth from lakes, land, river, streams, ocean, ponds and from trees by transpiration, this rises into the atmosphere in the form of a gas by convection. As this warm air rises, cold air moves in and meets the warm moist air which causes the warm air to rise rapidly forming large, dense thunderstorm clouds. Formed at a height between 15,000 to 25,000 feet above sea level, the water droplets are carried upward to a much cooler region until some of them are converted into ice (snow) particles.
During the thunderstorm, precipitation particles (water droplets and ice crystals) in the higher region of the clouds will then collide with each other as they rub against each other in strong currents of air. This strong air current here is due to the ascending (rising) and descending air in the updrafts and downdrafts of the storm. As a result, this colliding and rubbing of many water droplets and ice crystals creates a static electrical charge.
Thus, causing areas of negative and positive charge to develop within the thunderstorm. Some of the ice (snow) crystals and water droplets will therefore become positively charged (+ plus sign), while others become negatively charged (- minus sign). The positive and negative electrical charges in the cloud then separate from each other where the positively charged snow crystals moves to the upward top section of the storm cloud while the heavier negative charge ice crystal and water droplets drops to the lower section of the cloud.
When the difference in the charges at the lower section of the cloud becomes large enough, whereby reaching a certain strength, a giant "spark" occurs causing the flow of electricity (electrical energy ) to be released through the air to another point that has an opposite charge. This release of electrical energy is called a leader stroke which may be from one cloud to another (Cloud-to-Cloud Lightning) or from one section of the cloud to another (In-Cloud Lightning) or from cloud to the ground (Cloud-to-Ground Lightning). Once a connection is made and the path is complete, a surge of electrical current moves in the opposite direction back to the cloud and produce a flash of light which we call lightning. This process is called the main stroke.