Set aside fear and superstition, and you're still faced with one of the most awesome sights in the natural world. These twisting storm columns can reach wind speeds of 318 mph (512 kmph) and measure miles across, scarring the Earth and decimating homes and buildings in the process. Yet, in some parts of the world, these powerful storms are a regular occurrence.

The United States alone experiences more than 1,000 tornadoes a year, and the storms have been reported on every continent except Antarctica.

If you've ever watched a whirlpool form in your bathtub or sink while draining the water, then you've witnessed the fundamentals of a tornado at work.

A drain's whirlpool, also known as a vortex, forms because of the downdraft that the drain creates in the body of water. The downward flow of the water into the drain begins to rotate, and as the rotation speeds up, a vortex forms.

In a tornado, the same sort of thing happens as with our bathtub example, except with air instead of water. A great deal of the Earth's wind patterns are dictated by low-pressure centres, which draw in cooler, high-pressure air from the surrounding area.

This airflow pushes the low-pressure air up to higher altitudes, but then the air heats up and is pushed upward as well by all the air behind it.

The air pressure inside a tornado is as much as 10 percent lower than that of the surrounding air, causing the surrounding air to rush in even faster.

Tornadoes are among the most dangerous storms on Earth and, as meteorologists strive to protect vulnerable populations through early warning, it helps to classify storms by severity and potential damage. Tornadoes were originally rated on the Fujita Scale.

In February 2007, the Fujita Scale was replaced by the Enhanced Fujita Scale. The new scale rates tornadoes by 6 categories.

Tornado Facts

• The low pressure of a tornado doesn't cause buildings to explode – most damage comes from flying debris.
• Tornadoes occur most often between 3 and 9 p.m.
• Three out of four tornadoes touch down in the United States.
• The forward speed of a tornado can hit 70 mph.