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← How much water is there on, in, and above the Earth?

Richard Dawkins's Avatar Jump to comment 1 by Richard Dawkins

This is exactly the kind of image I love to use in presenting science, because it is counter-intuitive, yet very easy to check the calculation. Just note the diameter of the 'droplet' of water (a substantial fraction of the width of North America), then remember that the volume of an object goes up with the cube of the linear dimension, then smear the volume (4/3 pi r cubed) of water out over the available surface area and it all makes sense.

It's valuably counter-intuitive in the same sort of way as those calculations that show that every time you take a breath you are inhaling at least one molecule that went through the lungs of . . . name any historical character you like.

Tue, 15 May 2012 09:45:46 UTC | #941555