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THE SAFFIR-SIMPSON SCALE

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THE SAFFIR-SIMPSON SCALE

five categories of hurricane wind — and how much more damage each next one does

Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.

Three sizes in one archive — from a sheet on the fridge to a poster on the wall.

Standard$1.50

Payment and email are handled by Paddle. The download link arrives by email — no account, no password.

Formats
A4 · A3 · A2
What you get
Print-ready PDFs, one per size, with every letterform converted to outlines — nothing to install, nothing to shift.
Subject
science · reference · comparison · everyone · study

Above, the area of each square is the damage relative to Category 1. Below, the limits of each category in knots, miles per hour and kilometres per hour; the speed is the 1-minute sustained wind at 10 m.

CATEGORY FOUR WAS WIDENED BY ONE MILE PER HOUR

The NHC assigns hurricane intensity in 5-knot steps and rounds the conversions to mph and km/h to the nearest 5, so as not to suggest a precision the measurement does not have.

At the Category 4 boundary this broke down. 115 kt is a Category 4, but 115 kt is 132.3 mph, which rounds to 130 — and the old Category 4 began at 131. To keep the storm a Category 4 in mph as well, the NHC had to print a figure other than the one the conversion gives.

In 2012 the range was widened by one mph at each end, to 130–156 mph (113–136 kt, 209–251 km/h). The same thing happened in km/h: 135 kt gave 250, and the old range ended at 249. Not one hurricane changed category, in the record or since: the arithmetic was fixed, not the scale.

On the sheet

  • Above, the area of each square is the damage relative to Category 1. Below, the limits of each category in knots, miles per hour and kilometres per hour; the speed is the 1-minute sustained wind at 10 m.
  • Colour carries meaning, but meaning never rests on colour alone — the sheet reads in black and white.
  • Nothing about how it was made: the sheet carries only what the reader needs.

Printing

  • Three sizes in the archive: A4 — 210×297 mm, A3 — 297×420 mm, A2 — 420×594 mm.
  • All text is converted to outlines. No fonts to install, and nothing shifts on another machine.
  • White background and sparing fills — it prints on a home printer without draining the cartridge.
  • Margins of at least 10 mm: a home printer cannot print to the edge.
  • No stroke thinner than 0.3 mm, so nothing disappears in print.

Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 5 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.

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