---
source: https://iinventedlight.com/library/notes/tornado-basics.md
title: "Tornadoes and the Enhanced Fujita (EF) scale"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA NSSL, Severe Weather 101: Tornado Basics, US government work, public domain; NOAA SPC, Storm Prediction Center Enhanced Fujita Scale (EF Scale), US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: weather"
tags: science, weather, tornado, ef-scale
sources:
  - id: S1
    title: "Severe Weather 101: Tornado Basics"
    publisher: NOAA NSSL
    url: https://www.nssl.noaa.gov/education/svrwx101/tornadoes/
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Storm Prediction Center Enhanced Fujita Scale (EF Scale)"
    publisher: NOAA SPC
    url: https://www.spc.noaa.gov/efscale/
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Tornadoes and the Enhanced Fujita (EF) scale

## 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).