How Tornadoes Form

Every year, about a thousand tornadoes will randomly skip across America, some causing deadly destruction and leaving hundreds homeless. But what causes these writhing monsters to strike where they do? What exactly is happening inside that whirling funnel of dirt and debris as it reaks havack on the crops and homes beneath? When exactly will a tornado touch down? Sadly, meteorologists have yet to discover the answers to these puzzling questions, but what we do know about storms that produce tornadoes and about what a storm will look like when a tornado is about to touchdown, is quite helpful. Read over the following information, and learn something about the nature of a tornadic thunderstorm.

Almost all tornadoes are born from a parent thunderstorm called a supercell. A supercell is the monster of the thunderstorm family. Made up of thousands of convective cells, regular thunderstorms rapidly expand upward until their tops hit the stratosphere, causing them to flatten out and assume an anvil shape. A supercell occurs when many individual thunderstorms and clouds merge, creating an immense thunderstorm. The supercell expands vertically with updrafts and downdrafts of great force. Then, the storm begins to tilt slightly to one side and starts rotating. Before the tornado forms, a rotating cloud, called the wall cloud, emerges from the base of the supercell and lowers toward the ground. A vertically rotating column of air descends from the wall cloud while a swirl of dust and debris rises from the ground. When the column “touches down,” it becomes a tornado. Water vapor inside the tornado condenses, so a tornado is actually a cloud. Although only about 20% of supercells produce tornadoes, all supercells are capable of producing dangerous lightning, crop-stripping hail, dangerous straight-line winds, and torrential rains.