A tornado develops through a series of atmospheric conditions that come together under specific circumstances. Here’s a step-by-step breakdown of how tornadoes form:
1. Thunderstorm Development
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Tornadoes usually form from supercell thunderstorms, which are large, rotating storm systems.
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These thunderstorms form when warm, moist air near the ground meets cool, dry air aloft, creating instability in the atmosphere.
2. Wind Shear Creates Rotation
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Wind shear (a change in wind speed or direction with height) causes a horizontal spinning effect in the lower atmosphere.
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This horizontal rotation can be tilted vertically by the rising air in a thunderstorm updraft.
3. Formation of a Mesocyclone
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When the rotating air gets pulled into the updraft of the supercell, it can form a mesocyclone, a rotating column of air within the storm.
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The mesocyclone is the precursor to a tornado.
4. Tornado Formation
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Under the right conditions, the mesocyclone tightens and stretches vertically, increasing the rotation speed.
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A visible funnel cloud may form as pressure drops and moisture condenses.
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If this funnel touches the ground, it becomes a tornado.
5. Mature Tornado
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The tornado is fully formed and can cause severe damage.
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It continues as long as the storm’s structure supports it.
6. Dissipation
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The tornado weakens and eventually dissipates when the storm’s energy is no longer sufficient to maintain rotation.
Knowing the EF Scale and how they label tornadoes can help you determine if an area will have enough damage to explore.
The EF Scale, or Enhanced Fujita Scale, is used to rate the intensity of tornadoes based on the damage they cause to human-built structures and vegetation. Here’s a breakdown of the scale:
| EF Rating | Estimated Wind Speed (mph) | Damage Description |
|---|---|---|
| EF0 | 65–85 mph | Light damage (e.g., broken tree branches, minor roof damage) |
| EF1 | 86–110 mph | Moderate damage (e.g., mobile homes overturned, windows broken) |
| EF2 | 111–135 mph | Considerable damage (e.g., roofs torn off, large trees uprooted) |
| EF3 | 136–165 mph | Severe damage (e.g., entire stories of buildings destroyed) |
| EF4 | 166–200 mph | Devastating damage (e.g., houses leveled, cars thrown) |
| EF5 | Over 200 mph | Incredible damage (e.g., strong frame houses swept away, structural deformation of high-rises) |
The scale was introduced in 2007 to improve upon the original Fujita Scale, making the estimates more accurate in terms of wind speeds and damage correlations.
