Tornadoes are spawned from various thunderstorms, but more commonly the supercell. A supercell is a thunderstorm characterized by the strong updrafts, downdrafts, and windshear they contain. These are all parts of forming a tornado. Many of these things are caused by instability in the atmosphere from two airmasses colliding; one, a cold dry airmass, the other being a warm moist air mass. As the atmosphere begins to stabilize itself, this causes instability, thus resulting in the formation of wind shear and updrafts. Windshear is an upper level column of horizontally rotating air, that, when combined with an updraft, may form a tornado. Inflow, air that moves inyo or towards the base of the mesocyclone, often plays a role in the formation. This inflow feeds the storm, and brings it to intensify. A mesocyclone is a mass of rapidly rotating air, where many of natures most destructive tornadoes, such as the EF-5 are produced. This mass of rapidly rotating air can form a wall cloud, which also rotates with the rest of the storm. A wall cloud is a lowering in the clouds, and can often be identified by the rotation of this cloud, and how close to the ground it is. Sometimes, however, there are cases where the storm becomes rain wrapped, making us blind to the oncoming storm. The wall cloud is the updraft base of a storm, and where many tornadoes form.