Liz Kamerer asked:
I was swimming in the sea recently and noticed that the water had a swirling effect. Right next to where I was standing or any pillars in the water, it was really pronounced and we were trying to work out why it was happening.
Dave - You'll certainly see some swirling effects if you've got the water flowing past a column due to a tide - the wake formed can look quite swirly. You can also get whirlpools created by tides flowing round corners and water being sucked underneath, which form what used to be called maelstroms.
Chris - There's some incredible youtube footage of one off the west coast of Scotland
Dave - And there's some quite serious ones in the Strait of Messina that I sailed past once too.
Chris - Not into them I hope!
http://www.youtube.com/watch?v=8lA5az6ucG8 tommya300, Mon, 20th Sep 2010
Actually, just about any shearing movement of a fluid (air and water in our general experience) will form a vortex. For example, in water a vortex forms around ones hands and arms when swimming, and behind boat propellers. In the air there are some nifty pictures of vortices forming behind aircraft wings, but they also form around everything that sticks up into the wind, such as a house. They are everywhere, but difficult to see. SteveFish, Mon, 13th Dec 2010