MadSci Network: Earth Sciences |
Hello, Logan - Well, actually, the flow of water down drains has nothing to do with which hemisphere you are in; the Coriolis effect is much too small. It will be determined by random motions in the water (or, in the case of toilets, by the direction of the incoming water). Experiments have been done which show that the water will indeed drain in opposite directions in the northern and southern hemispheres if you are careful enough to eliminate all motion in the water first; this is very difficult to do, and will not happen by itself (it also requires perfectly symmetric containers). This is explained in the sci.physics FAQ, along with an equation that lets you calculate how still the water must be (as a function of how large the vortex is) in order for the Coriolis effect to be noticeable. Here is the reference: http://math.ucr.edu/home/baez/physics/bathtub.html Another reference which discusses the same subject, and which includes a description of the experiments which did show a preferred direction (so you can get an idea of how small the effect really is), as well as a description of an equitorial scam (watch out for this if you are ever in Kenya!) is the Bad Meteorology page: http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html Now, that being said, there is a real Coriolis effect; it is what determines the direction of the trade winds, and of the rotation of large storms such as hurricanes. There is a wide band around the equator known as the doldrums where the winds tend to be weak and variable in direction; this is the dividing line between the northern and southern hemispheres, but it is a wide line, not a thin one. Also, there would be general air circulation in the atmosphere even if the earth did not rotate, as the equator would still be hotter than the poles; warm air would rise at the equator and travel towards the poles, where it would sink, and there would still be a relatively windless zone around the equator.
Try the links in the MadSci Library for more information on Earth Sciences.