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Short answer

A tornado is a narrow, violently rotating column of air reaching from a thunderstorm to the ground. Tornado strength is rated after the fact, from damage, using the Enhanced Fujita (EF) scale. [S1][S2]

Key points

• Wind is invisible, so a tornado is hard to see unless it has a condensation funnel of droplets, dust and debris. [S1]
• About 1,200 tornadoes hit the U.S. each year. [S1]
• The U.S. threat shifts with the seasons: Southeast in cooler months, Plains in May and June, northern Plains and Midwest in early summer. [S1]
• Ratings come from damage: surveyors estimate the wind speed that would cause what they see. [S2] The original Fujita Scale dates to 1971. [S2]

Claims

• id: C1 claim: A tornado is a narrow, violently rotating column of air. source: S1 evidence: "A tornado is a narrow, violently rotating column of air"
• id: C2 claim: About 1,200 tornadoes hit the U.S. yearly. source: S1 evidence: "About 1,200 tornadoes hit the U.S. yearly."
• id: C3 claim: The scale estimates wind speed from the damage a tornado caused. source: S2 evidence: "estimate a wind speed associated with the damage caused by the tornado"
• id: C4 claim: Fujita relates damage to the fastest 1/4-mile wind at the damaged structure. source: S2 evidence: "relates the damage to the fastest 1/4-mile wind"

Sources

• [S1] Severe Weather 101: Tornado Basics. NOAA NSSL. https://www.nssl.noaa.gov/education/svrwx101/tornadoes/ . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Storm Prediction Center Enhanced Fujita Scale (EF Scale). NOAA SPC. https://www.spc.noaa.gov/efscale/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_fbat0x5r,
  author = {{iinventedlight}},
  title = {{Tornadoes and the Enhanced Fujita (EF) scale}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/tornado-basics/},
  note = {Permanent ID iil:note:fbat0x5r. License: CC-BY-4.0.},
}

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