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Name: ceci
Status: N/a
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993

Is it true that water in the southern hemisphere swirls the other way? Why?

Martin Gardner, in "The Ambidextrous Universe," a book I recommend to anybody, mentions some enterprising people in Kenya, which lies right on the equator. There was a line in the village where the equator was, and a few of these guys had some frying pans with a little hole in the middle. They would put water in and a twig on the water to make it easier to see, and, sure enough, on the north side of the line the water swirled out of the pan one way, and on the south side it went the other way! They apparently were quite good at this, and made quite a bit of money... Basically, nobody has ever (properly) demonstrated this effect with water in ANY size bathtub. The Coriolis effect is simply too weak to have any effect on an ordinary quantity of water. It does have a strong effect on the circulation of air in the atmosphere, however, and hurricanes in the southern hemisphere do indeed swirl in the other direction. An easy way to imagine the Coriolis effect is to think of the effect it has on missiles launched on a North-South trajectory. If the missile is launched north from the equator, it has a certain East-West speed as well due to the rotation of the earth. At higher latitudes, the rotational speed is lower because the distance to the rotational axis is lower (at the poles the rotational speed is zero), but the missile retains its initial speed in that direction, and thus appears to be bending out of its initial north-south direction relative to the ground. If launched south, the "handedness" of the bending is reversed. There has been concern expressed that the waste heat from large- scale fusion reactors could be significant. If current concerns about global warming are valid, we should give careful consideration to the potential effects of additional heating of the atmosphere.

A. Smith

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