Weak Tornadoes: F0 and F1

• The vast majority of tornadoes are considered "weak" tornadoes and are designated either F0 or F1 on the Fujita Scale. They are relatively short-lived, only staying on the ground for one minute or less. Well-built structures are usually left mostly unharmed by these tornadoes, but minor damage to roofs and chimneys may occur. Smaller structures such as mobile homes and other temporary homes can be knocked over. Trees often lose branches and can be knocked down if they have shallow roots. F1 tornadoes can also push cars off the road.
  
  

Significant Tornadoes: F2 and F3

• F2 tornadoes can cause serious damage to well-built structures. Roofs can be torn away completely from buildings, and outer walls can be collapsed. Mobile homes are almost always completely destroyed. Vehicles can be lifted off the ground by F2 and F3 tornadoes. F3 tornadoes can completely strip a wooded area of its vegetation. F3 tornadoes are significantly more deadly that F0, F1, and F2 tornadoes, but inner walls of well-built structures should be reasonably safe even if the outer walls are destroyed, as they most frequently are.
  
  

Violent Tornadoes: F4 and F5

• F4 tornadoes can completely destroy even well-built structures and flip over large vehicles such as trains and airplanes and sometimes move them great distances. Large trees are uprooted, and nothing less than a storm shelter can protect a person from the tornado. F5 tornadoes are the most powerful of tornadoes. They can rip the most well-built homes off their foundations and shred them and spread the wreckage for miles. Large steel vehicles are mangled beyond recognition, and structural debris is often reduced to coarse granular particles. F5 tornadoes are incredibly rare; there have been only 52 confirmed F5 tornadoes in the US since 1950.
  
  

Economic Impacts of Tornadoes

• Tornadoes do millions of dollars' worth of damage every year. One particularly bad year for tornadoes was 1999, which produced 74 tornadoes in Oklahoma and Kansas in less than 21 hours on May 3 and 4. When the rash of tornadoes was finished, 46 people had been killed and 686 people had been injured. The tornadoes also did $1.11 billion worth of property damage and $6,000 worth of crop damage. Tornado damage can also have other effects. Businesses can be destroyed, people can be left incapable of providing for their families because of injury or death, and storm shelters must be maintained at all times. All of these can prove costly.