The only significant similarity between tornadoes and hurricanes is that they both produce high-speed winds. Tornadoes form as the result of lingering strong vertical wind velocity and vertical temperature changes. Hurricanes form as the result of extended periods of weak vertical wind velocity and relatively low changes in atmospheric temperature.
Tornadoes are fast-moving storms that form quickly and last usually for only minutes. They are about 1/2 mile wide, with the largest tornado ever recorded measuring 2 1/2 miles, and generally affect only a small geographic area. By contrast, hurricanes are the slow-forming culmination of several storm fronts and are generally between 100 and 1,000 miles wide. They last for days or, in the case of strong hurricanes, weeks and can affect a geographic area that spans thousands of miles throughout their courses. Topography is another key distinction between tornadoes and hurricanes. Tornadoes typically occur on land. Although hurricanes may pass over land, they originate over water. This is due primarily to the fact that moisture powers hurricanes. This is also why hurricanes weaken when they pass over land. Hurricanes, however, do frequently produce the kind of storm conditions that spawn tornadoes once they hit land. This is why tornadoes and hurricanes sometimes occur simultaneously in areas prone to hurricanes.