EPOD , 1/4/2012

The interplay and light on water is an endless source of fascination. Take a source of light (usually the Sun), add water and a little wind or in this case a tossed pebble, and viola! A unique, evolving pattern of light is formed illustrating, as always, the laws of physics.

On an irregularly wave-rippled surface, a more commonly seen glitter path would have been present. In this picture however, the laws of optics, not in any way perturbed by the imposed circular symmetry of the expanding waves, still have their way. Only those portions of the water surface that have the appropriate slope and orientation will reflect light into the observer's eyes. These are seen as glints. The star-like glints are optical artifacts of the camera, creating a pleasing symbiosis of nature and technology. Photo taken in early November 2011 at Lake Wylie, North Carolina.

Published on EPOD (http://epod.usra.edu/), 12/16/2009

Shimmer tree

What is going on here? Has the space-time continuum been distorted by a pulse of gravitational waves from a nearby supernova? Well, not quite. Gravity waves (not gravitational waves) are responsible for the shimmer effect: surface gravity waves on the surface of the pond. But why is the distortion most pronounced near the top of the picture? By now you’ll have realized that you’re seeing the distorted reflection of a deciduous hardwood tree in that pond, and as the waves spread out radially, their "curvature" decreases, so the waves at the top of the photograph were in reality nearer to me as I took the picture. By the way, it was only after I photographed this scene that I noticed a sign “Please do not throw rocks in the pond!”
Notice how the reflection of the cloudy sky is darker near the bottom than the sky itself – a consequence of the varying reflectivity of light at different angles of incidence on the pond. Photo taken in Lancaster, Pennsylvania on December 4, 2009.

Published on EPOD (http://epod.usra.edu/), 12/30/2007



The photo above was taken in the middle of June 2007 during a visit to Yellowstone National Park in Wyoming. One can view the impressive Lower Falls of the Yellowstone River from several vantage points, each offering a distinct perspective. This shot was taken near the bottom of a 328-step descent on a metal stairway. The stairway provides excellent views of the waterfall on the way down. Spray from the water as it thunders onto the rocks below drifts quite some distance from that point, resulting in attention getting spray bows, when the Sun is shining. Though I took many pictures, some exhibiting the secondary bow as well, this was my favorite. The Sun was of course behind me, and the spray droplets were of such a size and density as to reproduce typical rainbow colors and intensity, yet, unlike many rain showers, still allow the background to be clearly seen.

Published on EPOD (http://epod.usra.edu/), 11/2/2011

The photo above shows a chunk of scalloped ice, about 65 ft (20 m) in width that broke off from the Sawyer Glacier near Tracy Arm Fjord in southeastern Alaska. Note the pure blue color emanating from within the “chasm.” The mechanism responsible for producing this robin’s egg blue color, as well as the blue color in deep snow, is essentially the same as that giving deep water its blue color. The longer wavelengths (yellow and red light) present in the incident white sunlight are preferentially absorbed by ice crystals. As a result, what we see is what’s not absorbed -- reflected light that’s dominated by the green and blue portion of the spectrum. In general, the thicker the ice the greater the absorption, and thus the bluer the color. Though this color may look sky blue, Rayleigh scattering causes the colors we see in the sky on a clear day, not absorption and reflection by air molecules.

The melting patterns on this medium sized iceberg look as if someone has scooped out the ice with a scallop shell. So-called "spontaneous pattern formation" is ubiquitous in nature. The particular mechanism inducing these undulations may involve local melting of parts of the surface, which grow locally as a result of a feedback mechanism. For example, perhaps there’s an initially small and shallow depression that creates a region of shadow, outside of which more melting occurs, changing the shadow boundary, and so on. Photo taken in June 2011.



Published on EPOD (http://epod.usra.edu/),  June 1st, 2011.

A golden glitter path has its linear form furrowed by the waves emanating from a passing speedboat. As the waves expand and arc out, the reflection sites change and a previously undisturbed ‘cylinder of Sun’ is restructured and distorted. A glitter path is made up of a myriad of glints; tiny, almost point-like transient reflections of the Sun from suitably placed wavelets on the surface of the water. The shape and angular extent of a glitter path is determined by the solar elevation, the distribution and size of the waves and the position of the observer. So they can, and do, vary enormously from place to place and hour to hour. This photograph was taken in Sandbridge, Virginia on the evening of April 30, 2011.

Yosemite Sunset

Fibonacci Spirals!

Abraham Heschel quote

“Finite meaning is a thought we comprehend; infinite meaning is a thought that comprehends us; finite meaning we absorb; infinite meaning we encounter.  Finite meaning has clarity; infinite meaning has depth.  Finite meaning we comprehend with analytical reason; to infinite meaning we respond in awe.  Infinite meaning is uncomfortable, not compatible with our categories.  It is not to be grasped as though it were something in the world which appeared before us.  Rather it is that in which the world appears to us.  It is not an object – not a self-subsistent, timeless idea or value; it is a presence.”

Abraham Heschel, Who Is Man? p.78 (as quoted by Skip Moen, skip@skipmoen.com)