Math Mysticism: is Hurricane Shape a Fibonaci Spiral?

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Math Mysticism: is Hurricane Shape a Fibonaci Spiral?

Xah Lee, 2011-08-28

Please beware of the golden ratio math mysticism trash spreading online.

Fibonacci spiral hurrican Irene
Illustration giving the impression that hurricane Irene has a shape of so-called “Fibonacci spiral” Source

I'm seeing people sharing this image online (e.g. Reddit, Twitter, Google+). It is true that the hurricane has the general shape of a equiangular spiral (aka logarithmic spiral), which is the shape that many (but not all) natural growth takes (e.g. Seashells), but putting that golden-ratio block "spiral" there is completely baseless.

The so-called “Fibonacci spiral” you see in the pic is made up of parts of circles, stacked on blocks of rectangles who's ratio of the sides is the golden ratio. Such spiral is only a approximation of one particular equiangular spiral. (equiangular spiral is a family of spirals. See: Equiangular Spiral.)

Also, hurricane does not really have a definite shape, we can only say it's roughly that of equiangular spiral based partly on physics and appearance.

If you don't have a degree in math, you might be all confused about this Fibonacci number , the Golden ratio, and the various spirals. It is true that mathematics is mysterious, and many shapes in nature are well described by math, but if you see any online blog or math popularizing books that carelessly connect it with mysticism, about how some numbers or shapes is everything in the universe, beware, it's stretched to garbage.

For highschool-level explanation of the equiangular spiral, see: Equiangular Spiral. For other spirals, see: Archimedean Spiral, Lituus.

For debunking of the Fibonacci number and “golden” this that, see:

  • Fibonacci Flim-Flam (2008) By Donald E Simanek. @ Source
  • The Myth That Will Not Go Away (2007-05-) By Keith Devlin, Mathematics Association of America. @ Source
fibonacci spiral girl
When a attractive girl flips her hair, the water stream formed is a Fibonacci spiral. ☺

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