> Isle Royale came to my attention through this list, otherwise I might
> never have known of it.
So, when do you want to go?
> I fly over/past it periodically on trips between Toronto and Thunder
> Bay, so I see it from FL220 or so. The island is long and thin, vaguely
> east-west, and along the shores there are parallel and much smaller
> island-lets with gaps between.
Yup. Lots of shoreline irregularities. :)
> These gaps act as irregular, natural diffraction gratings, and -
> depending on the prevailing wind - the water between the small islands
> and the main usually shows interference patterns.
I think there are several factors in play.
1. Long wave action of Lake Superior. These are mostly broken up by
the shoals surrounding the Islands, but enough gaps exist that they
flow through any openings. However, as they traverse the openings,
there is a phase shift and directional change.
2. The coves are long and narrow. A long wave coming in from Lake
Superior will effectively change direction to line up with the cove.
3. Wind direction. The wind direction and current flow are at almost
90 degrees of each other. This will cause a dual wave action on the
long coves where you have the waves travelling with the wind and other
waves going sideways.
4. Rocky shorelines. The waves bounce off of the rocks and also
refract around every imaginable point. This is happening from a
wind-direction, current-direction, and long-wave direction
perspective. So, you may end up with three distinctly different wave
patterns on the coves as well as varying forms of refraction along the
shoreline.
5. Water clarity. The water is very clear. The bottom shapeshifts and
the bottom, which is mostly very large rocks and gravel, alters the
visual stance.
6. Given the viewing distance, and the multiple beat patterns and
extremely short peak-to-peak distance, you are very likely
experiencing a prismatic effect, which gives the waves on the coves
colors. A couple years ago, even some of the Google Earth images
showed this.
> I think of the coincidence that list members have photographed there,
> uniting the photographic concepts of diffraction and interference and
> the natural effects in the water.
Coincidence? There were FOUR E-1s in our little group. I think that
must have messed something up.
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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