Dunno if it's YART or not, but I have more info than you'll EVER need on this one!
Tornadoes and other such things (like ocean circulation) rotate one way in the NH (= oceanographer-ese for Northenr Hemisphere) and t'other way in the SH. Easy weather application: Wind blows
counterclockwsie around a low pressure system in the NH.Take any weather map showing pressure contour lines, and look at it. A good first estimate of wind velocity and direction can be made by looking at the contour lines. The wind blows ALONG the contour lines (direction determined by whether you have a high or low pressure system) and the strength can be estimated by how close the contour lines are closer together (PM me for a formula if you REALLY want to know!). If the lines are very close together, you have a strong wind - farther apart, a weaker wind. Try it - find yourself a contour map of the atmospheric pressure in your part of the US right now and figure out which way the wind "should" be blowing (remember, CCW around low pressure and thus CW around high pressure) and then check the weather report to see if you're right! (There are other factors involved, especially geographic things like hills, mountains, etc., so it doesn't always work out perfectly.)
Any SH readers should turn that around - it would be CW around a low-pressure system, and CCW around a high-pressure system. Anyway, like I said, ocean circulation follows the same sorts of rules. In oceanography (and presumably atmospheric science) we use "cyclonic" (= low-pressure in the centre) and "anticyclonic" (= high-pressure in the centre) to remove the hemispherical ambiguity. That is, if you know your physics, you can always figure out the actual direction if someone says "cyclone in the NH" for example.
I like the quote in my oceanography book "However, the observer in the southern hemisphere is upside-down relative to the observer in the norther hemisphere and he calls the motion anticlockwise...It is a matter of point of view."
