There are about a thousand tornadoes every year in the United States. While 74 percent of tornadoes are weak, they have a significant but reparable effect on humans and nature. The impact of the remaining 26 percent can be much more substantial. Tornadoes are different than other natural disasters, such as hurricanes, because they are confined to a relatively small area (typically a few hundred meters wide). Though hurricanes have more total energy, the energy density within a tornado can be much higher.

The Enhanced Fujita scale is a measure that determines the strength of a tornado. It was updated from the original Fujita scale in 2007. The storms are rated on a scale of EF0 through EF5. From the amount of damage a tornado causes, scientists are able to determine the approximate wind speed within the tornado. An EF0 has a wind speed between 65 and 85 miles per hour, which can tear branches off trees or shatter windows with debris. An EF5 has speeds greater than 200 miles per hour. EF5's have caused cars to fly through the air like missiles.

Tornadoes typically kill 60 to 80 people per year and injure more than 1,500. Most deaths come from flying or falling debris, and occur in the most violent tornadoes. Violent tornadoes (EF4 and EF5) comprise about 2 percent of all tornadoes, but they account for 70 percent of tornado deaths.

In the event of a tornado, seek the sturdiest structure available. Move away from windows, and stay as low to the ground as possible.

Another significant effect tornadoes have on humans is the property damage. Weak tornadoes can take the roofs off buildings and break windows. Stronger tornadoes have been shown to level buildings. This can have a considerable economic impact. In 1999, Oklahoma suffered about $1.1 billion in property damage and crop losses from tornadoes.

When you consider the size of Earth, tornadoes have a relatively small effect on the overall environment. However, the areas where tornadoes strike are greatly impacted. Trees and plants can be uprooted, and diseases in the soil are spread. Wildlife loses their lives or habitat.

Be that as it may, the effects of tornadoes on the environment may not be all negative. Biologists are researching the possibility that tornadoes are responsible for certain small animal and plant life being spread throughout parts of the United States.