What causes tornados?

skysmom65

A tornado is a vortex of air, swiftly rotating around a lower-pressure core. Due to the Coriolis force, air in the atmosphere will not flow directly into a low-pressure area, but will be deflected. This is the start of rotation, and the air will preserve its angular momentum, subjected to a pressure-gradient force in equilibrium with a centrifugal force. As a result, the low pressure core will remain, and the vortex will only grow in length, trying to suck air in from its two end points. As soon as any such air vortex, generated by a storm or other convective cloud, reaches ground, it is called a tornado. It consists mainly of rotating air, condensed water vapor (due to the lower pressure), and dirt and debris in its lower part near the ground. How does a tornado form? The (usually) destructive kind of tornado, occuring in the USA during the spring and summer, is produced by a special kind of severe thunderstorm called a supercell. A supercell storm distinguishes itself from othertypes of storms by the fact that the entire storm's updraft rotates, and because is has a well-organized inflow/outflow system. These storms may continue for hours, wreaking havoc on anything that they pass over. http://www.stormchasing.nl/tornado.html Mar 05 07, 7:20 AM

rockyroad8

Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation. Moments later a strong tornado develops in this area. Softball-size hail and damaging "straight-line" winds also occurred with this storm http://www.wate.com/Global/story.asp?S=367963 Mar 05 07, 8:46 AM