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| [Note Guidelines] Photographer's Note |
My posting of this aerial shot was inspired by the earlier post by jamesp of a very nice glacier photo (Medial Moraine and Deformation Crevasses). His closeup shows the detail, while this view gives some of that plus the "big picture".
I'm fascinated by the record of glacial flow in the moraines. The large medial moraine dominating the lowest part of the glacier is actually the combination of two medial moraines. One is from the major merge immediately upstream and the other is from the second tributary glacier to the right above that merge. The first and second tributary glaciers on the right branch provide an interesting contrast.
The first tributary glacier comes from a small but steep valley and is therefore both smaller and fractured. If you have ever read of Everest expeditions and the dreaded Khumbu Icefall, this is the same basic phenomenon. As the glacier reaches an area of increased slope, the back pressure decreases and the flow increases enough to cause partial breakup of the ice mass. This is a lot like a slower version of a river going over the brink of a waterfall and making the transition from a single smooth stream of water to smaller streams, then droplets and spray.
The second tributary glacier comes from a larger flatter valley and merges smoothly without the fractures. In the process it creates a large medial moraine which merges with the lower medial moraine some distance below the actual merger point in the left center of the photo.
Photo/technical notes-
1) My best estimate of location is in the Wrangell-St. Elias National Park and Preserve of SE Alaska (not the panhandle). If anyone can pinpoint the spot, be my guest- you would have my profound admiration for your geographic skills.
2) This was shot from near the tail of a 747-400 en route from Chicago to Tokyo. The bit of engine in the upper right was left there as a reminder of the photographic difficulty of the situation. I always carry my camera with me on such trips, for reasons such as this. Add the advance planning needed to get a window seat well behind the wing and you have some good photo-ops for no extra cost. Consider time of day, sun angle, planned route, and which side of the plane when picking a seat. Once flying, a small travel atlas can help track your location and identify features you might capture (not an easy task).
3) This shot was taken with my Olympus 700C-UZ, but at a fairly wide angle, so it could have been taken with any small camera. The smaller the camera, the easier it is to use in this cramped situation. The greatest technical issue with shooting from a plane is that you have no control at all of the lighting. Second is the quality of the window, both scratching/hazing and frost formation. If you are lucky, these will not prevent you from catching something interesting. Shooting through the engine exhaust can destroy the focus because of the turbulence, but it is possible to shoot between or below the streams (easiest with a long zoom lens).
4) Once you have captured the image, post-processing is virtually mandatory. This shot was darkened a fair amount and a LOT of contrast was added. Other than that, nothing was done.
Hope both picture and note prove interesting and educational. |
Jamesp has marked this note useful
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- Jamesp
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(13290) - [2007-11-23 23:03]
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Hi Bob
A good codition of a wonderful glacier system. I have no idea where it is, but from the amount of ice, Wrangel-St Elias would seem appropriate.
James
Hi Bob,
This looks like a textbook illustration. There would be no confusion about moraines after seeing this. It is a super shot... and to think you got it through those awful airliner windows. Nice work.
TFS
Evelynn : )
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