The Water: Wind Effects
Wind Driven Water: Langmuir Streaks and Kelvin Waves
Windrows, wind slicks, wind streaks, whatever you may call them, you've probably seen them. Long rows of foam, debris, and flat or 'slick' water arranged parallel to the current and at a slight angle to the wind. On the Finger Lakes, such a streak is often seen downwind of a major point, too, and the effect is the same though the forcing mechanism is different. These "windrows" are actually areas of upwelling and downwelling. The foam, debris, and dirtiest water collect at the downwelling zones and the slicks form where water is upwelling. This is important! See a slick on a windy day? Stay away, chances are it's void of life. Fish the debris lines, not only are leaves and sticks collecting there but also phytoplankton, mysis shrimp, baitfish, and game fish!
Long helical currents form these windrows. The water blown downwind begins moving in a spiral, and where two opposing spirals meet a slick or windrow is formed. When both spirals rotate down, the windrow is formed. (Where the center and left-hand currents meet in the pic at right. Each of the three "logs" represents one of these spiral currents.) A line of foam, leaves, sticks or other debris gathers at the intersection of these downward moving spirals. This downward motion collects all sorts of organic matter, including the trout and salmon!
A Kelvin Wave is a shorebound wave that follows the perimeter of a body of water. Generally unimportant to fishermen, it is nonetheless an interesting phenomenon. (If you like hydrodynamics and are a physics geek, that is!) Just a few notes, I don't want to bore anyone too much. Think of a Kelvin wave as a mound of water that hugs the shore, tallest at the shoreline and becoming smaller out into the lake. These waves are caused by an interaction between wind, the Coriolis Effect, and a boundary such as a shoreline. This boundary can also be the equator, though outside the scope of this page: please google "equatorial Kelvin Wave" for more information.
In the Great Lakes and larger Finger Lakes, (and throughout the Northern Hemisphere) shoreline Kelvin waves always move with the shoreline on the right, that is, they propagate in a counter-clockwise direction. The reverse is true in the southern Hemisphere- Kelvin waves travel in a clockwise direction. At the equator, they meet each other travel to the East. And no, it's not responsible for the direction the water in your sink, tub, or loo swirls when it drains! It's a different mechanism, long-scale waves in much larger bodies of water.