How do tornadoes form?
Exactly how tornadoes form is still not completely known. But after many years of study, meteorologists, scientists who study weather, do know some things for sure. Tornadoes can form as part of several different types of storms but they are produced inside powerful thunderstorms more than any other. Tornadoes form where warm, moist air and cold, dry air meet and begin to create updrafts that develop into massive rotating cumulonimbus clouds or supercells. Sometimes a spinning column of air called a vortex forms within these clouds. When this vortex becomes visible as a funnel cloud and reaches the ground, a tornado is created. Not all tornadoes form as part of a thunderstorms. Meteorologists have discovered that sometimes a horizontal layer of air can be set spinning. This happens when it gets caught between two other layers of air that are moving in opposite directions. This would be similar to rolling a pencil between your hands. With the help of updrafts and gravity this column can
Brittany – In order for a tornado to form, a number of different things have to happen. The first thing that has to happen is that you have to have two different patches of air moving toward each other from opposite directions, with a warm one on the bottom and a cool one on the top. (Pictures all come from ABC News.) The next thing that happens is that the warm air rises. (You may have learned about hot air rising in school.) After the warm air goes up, the cool air comes down to take its place. So now the warm and cool patches of air are moving side to side and up and down. So they make a spinning patch of air along the ground. This is probably pretty hard to imagine, so check out the picture: Usually when a tornado is starting, it happens during a storm. So there s lots of air moving around already. If a draft of air from the storm comes along close to the ground and then moves upwards (called an “up-draft”), it will pull the spinning air upwards. Now comes the part that we don t un
On average, about 800 tornadoes occur in the United States each year. They can appear and disappear in moments, and key details about their formation are unknown. These factors make the research to understand and predict tornado occurrence extremely difficult. This video segment adapted from NOVA describes the challenges of studying tornadoes and shows how computer simulations are helping researchers observe what they can’t possibly see in a real storm.
This is far from being completely understood. See my essays on tornadoes: (1) thoughts after VORTEX and (2) defining a tornado. Basically, we currently believe many tornadoes come from supercell storms but some tornadoes are produced by non-supercell storms. A supercell is a rotating storm, but not all tornadoes come from supercells and not all supercells produce tornadoes. Trying to understand more about tornadoes was a major purpose of the VORTEX project. Tornadoes develop from weaker vortices that “spin up” into tornadoes. Under the right conditions, the initial weak vortex undergoes a process called “stretching” … not unlike the way an ice skater spins up by pulling in his/her arms … in physical terms, this is known as conservation of angular momentum. Once it begins, the development of a tornado can proceed very quickly … in a matter of a few minutes. The weaker vortices that sometimes become tornadoes apparently can form in a number of different ways, so not all tornadoes h
