Since tornadoes are so elusive and so violent, it's almost impossible to get accurate wind speeds from inside the funnel.
So scientists have developed a scale that allows an estimate of a tornado's wind speed by examining the damage left behind.
That scale is called the Enhanced Fujita Scale, and it classifies tornado damage from EF0 (light damage) to EF5 (total destruction).
• EF0 (65-85mph) - Light damage. Minor damage to roofs or gutters. Tree branches broken off, and some smaller trees blown over.
• EF1 (86-110mph) - Moderate damage. Roofs stripped. Mobile homes flipped over. Significant window/glass damage.
• EF2 (111-135mph) - Considerable damage. Mobile homes destroyed. Roofs blown off well-built homes. Large trees uprooted.
• EF3 (136-165mph) - Severe damage. Large buildings (shopping centers) heavily damaged. Entire stories of well-built homes blown away. Cars lifted and thrown.
• EF4 (166-200mph) - Devestating damage. Well-constructed houses reduced to rubble.
• EF5 (over 200mph) - Total destruction. Well-built homes blown away from their foundations. Cars thrown hundreds of feet. High-rise buildings suffer structural damage.
Thankfully, research shows that more than half of all tornadoes are EF-0. Fewer than 1 in 1,000 reach EF-5 strength, which approximates about 1 EF-5 tornado per year in the U.S.
