There is much we do not know about tornadoes. Tornadoes are most common during the Spring when greatly contrasting air masses collide to produce severe storm systems. Wind shear within the severe thunderstorm causes rotation of air about a horizontal axis. The rotating circulation is tilted into the vertical by the updrafts in the thunderstorm. As the rotating air increases in height and shrinks in size a mesocyclone is formed. For whatever reason, a tornado funnel is spawned within the mesocyclone. Group of answer choices True False