A thunderstorm is formed from powerful updrafts, which are air currents that push upward. When a droplet starts to fall, it is pushed back upward by the rising air. As it rises, it gathers more ice crystals on its surface. It gets heavier, so it falls again. The cycle continues until a ball of ice is formed that is too heavy for the updrafts to pull back up.
Thunderstorms form when warm, moist air collides with cooler, drier air.
The atmosphere is unstable when cooler air is situated on top of warmer air because cold air is more dense than warm air. The warmer less dense air rises up through the cooler more dense air. The rising air causes updrafts to form, while air which is higher in the atmosphere cools and begins to sink, causing down drafts to form. History Lightning More Lightning Thunder Severe Storm Safety A Tornado is an extremely violent and destructive whirlwind. It extends down from a mass of dark clouds as a whirling funnel and moves over land in a narrow path.