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Environment

Image of the Day: Lee Wave Lenticular Cloud at Sunset

ImaGeoBy Tom YulsmanNovember 11, 2013 3:40 AM
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A lee-wave lenticular cloud at sunset, shot from Sawhill Ponds west of Boulder, Colorado, Nov. 9, 2013. (Photo: © Tom Yulsman. All rights reserved.) Date night with my wife started out in spectacular fashion over the weekend with a walk at sunset. I noted that a beautiful cloud formation had set up over the Front Range Mountains near Boulder, Colorado. So we positioned ourselves at the edge of this pond to watch the fireworks. The photo above is a fairly accurate representation of what we saw. More about the photographic details in a minute. But first, this is what's known as a lee-wave lenticular cloud. I wrote about this once before, in my second post at ImaGeo. You can find it here. Suffice it to say that winds blowing across a chain of mountains can cause standing waves in the atmosphere. These are not all that dissimilar from waves downstream of rocks in a stretch of river rapids. If conditions are right, a cloud can form at the apex of one of the waves in the lee of the mountains, and persist. The result: a lee-wave lenticular cloud. Sometimes, lenticular clouds look like flying saucers. But when the wind passes over an elongated range of mountains, the lenticular clouds can be elongated as well. Here's an animation of satellite images from the Cooperative Institute for Meteorological Satellite Studies showing the formation of these kinds of clouds over Nevada:

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Lenticular clouds forming downwind of the Spring Mountains to the northwest of Las Vegas, Nevada on Sept. 14, 2007, as seen in animation of GOES satellite images. (Source: CIMSS) Lastly, what about the photo itself? If you're interested in the gory details, here's a bit of photographic geekery (otherwise known as EXIF data):

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I imported the photo into Aperture on my laptop. The original, RAW image was a bit darker than what you see here, with detail lost in both the shadows and the highlights. I used the curves control to adjust the tonal values of the shadows, midtones, and highlights to better approximate the way the eye perceives light in nature.

I think my wife would agree that the photo is now closer to what we saw on the shore of the pond at the start of our night out.

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