Snell’s Circle A knowledgeable angler understands the phenomenon called the trout’s window. Wikipedia describes… Snell's window…[as] a phenomenon by which an underwater viewer sees everything above the surface through a cone of light. This phenomenon is caused by refraction of light entering water and is governed by Snell's Law. The area outside Snell's window will either be completely dark or show a reflection of underwater objects…[glare] Since the window is cone shaped, its diameter increases as the trout’s depth increases. For fishing purposes, the diameter of the window is double the fish’s depth. A fish two feet down has a four-foot window, one inch down produces a two-inch window. The higher the fish is in the water column the closer you can get, but the more accurate your cast must be. The following clips from the Underwater World of Trout by Wendell “Ozzie” Ozefovich. (http://underwateroz.com/) illustrate the window. Here is a trout and its window. A mirror like glare surrounds the window separated by an edge. This edge magnifies organisms as they enter the window.
http://underwateroz.com/ Here is another shot of the trout with the window, edge and glare. Notice our trout can see the bottom by looking at its reflection off of the glare.
Here our trout is scrutinizing a food organism,
http://underwateroz.com/ He inhales it
http://underwateroz.com As the food goes down its throat…
…an angler enters the window; our fish returns to its sheltering lie.
This angler has no understanding of the trout's window. If he did he would stay out of it and wear earth tones. A trout’s primary protection is his vision. Anything appearing in his window that isn't normal will spook him. Point to remember When you approach the stream, take a moment to analyze it. Fish the prime lies first. Be aware of the window. Don't waste valuable fishing time in water that isn't productive while spooking fish.
For more information about Trout Lies and Snells circle click here.
To check out Qzies wonderful underwater videos click here
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