ABOUT TORNADOES: A tornado begins with a thunderstorm cloud, which can build up a lot of energy. If this energy creates a particularly strong updraft of air, it will form a vortex, much like how a whirlpool forms in a draining bathtub. The air is pulled toward the center in a spiral, forming a tornado under the thundercloud. Wind speeds can reach 200 to 300 MPH, and if the dangling vortex touches ground, the combination of the whirling wind's speed, the updraft, and pressure differences can cause severe damage. The path of a tornado is determined by the path of the parent thundercloud, but it will often appear to hop (called a "jumper"). This occurs when the vortex is disturbed, causing it to collapse momentarily and reform.
GRAVITY WAVES: Atmospheric gravity waves are similar to waves on the surface of the ocean, but they are in the air instead of on water. The waves are set in motion by a disturbance in the atmosphere such as a change in the wind speed or direction, a sudden updraft from a thunderstorm, or a change in the jet stream high in the atmosphere. Atmospheric gravity waves act just like the ripples around a rock thrown into a pond. Gravity keeps the waves rolling. When an atmospheric gravity wave meets a thunderstorm, it pushes down on it, which squashes it and makes it spin faster. This spinning storm is more likely to produce a tornado.