Chromatic Snow Sparkles

<div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: left;">Looking at this photo that I just took, you might assume that it's a view of the stars and planets in the night sky, but it's not that at all.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJL8i0Pf5YdiazZVyDUEfNMlVCvPBIk1MQH0d2Vx322QCNSLUPxPY0AzlatEJrw0H02Us4nRbFUpHYL_pFGcvWYJIb2P6LoZPDirfk6rMr9XQMzfmKnHWAoHB5AXK59flEUHxNWA3Ytp6B/s1600/Snow+sparkles.det.sm.jpg" imageanchor="1" style="clear: left; display: inline !important; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJL8i0Pf5YdiazZVyDUEfNMlVCvPBIk1MQH0d2Vx322QCNSLUPxPY0AzlatEJrw0H02Us4nRbFUpHYL_pFGcvWYJIb2P6LoZPDirfk6rMr9XQMzfmKnHWAoHB5AXK59flEUHxNWA3Ytp6B/s1600/Snow+sparkles.det.sm.jpg" width="400" /></a></div><div class="separator" style="clear: both; text-align: left;">It's a view looking down at the snow outside our breakfast window. The colored lights are sparkles of sunlight reflected and refracted internally inside snow crystals. Like a prism or a rainbow, the hexagonal crystals break the light into component wavelengths, giving the observer a variety of colors sampled from the rainbow: red, magenta, yellow, cyan, blue, and violet.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">I took the photo with a digital SLR underexposed enough for the colored sparkles to register.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZKmSJk4D5bQSOzlqirtL92rp-f2B6TI50GR_yUmNEJ0ng5Tg5CeP5EvgriTfZH6tUZQl_UFcGGF497oplQIDHxxFhKyvgj7TFyyy1rkVFDiGRSQkbNWK2Wt8vFYVJbHjJL_ZzROEHk6qk/s1600/Snow+Sparkles+wide.sm.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" height="325" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZKmSJk4D5bQSOzlqirtL92rp-f2B6TI50GR_yUmNEJ0ng5Tg5CeP5EvgriTfZH6tUZQl_UFcGGF497oplQIDHxxFhKyvgj7TFyyy1rkVFDiGRSQkbNWK2Wt8vFYVJbHjJL_ZzROEHk6qk/s1600/Snow+Sparkles+wide.sm.jpg" width="400" /></a></div><div class="separator" style="clear: both; text-align: left;">The conditions today are perfect for chromatic snow sparkles. It snowed three days ago, and has stayed below freezing since then, allowing the crystals to grow larger. This morning the temperature was five degrees Fahrenheit. </div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">It appeared to me that the colored sparkles are most pronounced about 45 degrees away from the sun. In the photo above, that band passes through the right central part of the picture, with the sun coming from the left. </div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">If you look at the sparkles on an angle farther away from the sun—or closer to the sun, the chromatic effect is much less noticeable.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">Related previous post: <a href="http://gurneyjourney.blogspot.com/2008/06/annular-highlights.html">Annular Highlights</a></div><div class="separator" style="clear: both; text-align: left;">Related topic: <a href="http://en.wikipedia.org/wiki/Sun_dog">Sun dogs</a> (rainbow effects on ice crystals in the sky near the sun)</div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZKmSJk4D5bQSOzlqirtL92rp-f2B6TI50GR_yUmNEJ0ng5Tg5CeP5EvgriTfZH6tUZQl_UFcGGF497oplQIDHxxFhKyvgj7TFyyy1rkVFDiGRSQkbNWK2Wt8vFYVJbHjJL_ZzROEHk6qk/s1600/Snow+Sparkles+wide.sm.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: center;"><br /></a>

Chromatic Snow Sparkles

Looking at this photo that I just took, you might assume that it's a view of the stars and planets in the night sky, but it's not th...

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Sun Pillar

<div class="separator" style="clear: both; text-align: left;">We saw a good sun pillar last night, though my photo didn't come out as well as this one from the web.</div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzR_EcqIaFIgBqiv92H_Y4aa-byEsErcDtzbovbs_qcIQ2JVZvlXVrE9xOxGhOTaW2Fa2dHKoR-U_bgAHSq2JltG8-QhrHL5-rzr6INCm8Pkd5t_i2unNGR8j4HkaK9gb7xqBy6A0nEZQ/s1600/Sun_pillar_and_kitesurfers.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzR_EcqIaFIgBqiv92H_Y4aa-byEsErcDtzbovbs_qcIQ2JVZvlXVrE9xOxGhOTaW2Fa2dHKoR-U_bgAHSq2JltG8-QhrHL5-rzr6INCm8Pkd5t_i2unNGR8j4HkaK9gb7xqBy6A0nEZQ/s320/Sun_pillar_and_kitesurfers.jpeg" width="318" /></a><br />A "sun pillar" or "solar pillar" is a vertical shaft of light extending upward from the sun. It appears when the sun is at or below the horizon.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYQBqmHepPDkKGTs-Uprj0bntvZ1Tpcjzdgy321kxNvRUM0FqqPudoPeJ6-rGIbPbsjSIMn0S9J0UKhiudbrd6GwtWyOujVMORlI0pdckhzjrGvfvCxBO1lmcDo7ADKU6WmZb2kfU0Nnk/s1600/iceplate.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYQBqmHepPDkKGTs-Uprj0bntvZ1Tpcjzdgy321kxNvRUM0FqqPudoPeJ6-rGIbPbsjSIMn0S9J0UKhiudbrd6GwtWyOujVMORlI0pdckhzjrGvfvCxBO1lmcDo7ADKU6WmZb2kfU0Nnk/s1600/iceplate.gif" /></a>The light in the pillar reflects off the bottom surfaces of ice crystals that are suspended in the air. Those crystals are like tiny hexagonal dinner plates, floating in a horizontal position. Their flat surfaces act like mirrors to reflect the rays of sunlight down to the viewer. (Left: photo by W. A. Bentley)<br /><br />When such a pillar appears over an artificial light at night, it's called more generally a "light pillar."<br /><div class="separator" style="clear: both; text-align: left;"><a href="http://www.islandnet.com/~see/weather/eyes/pillars.htm">Detailed explanation (with photos and diagrams) from Weather Doctor</a></div><a href="http://en.wikipedia.org/wiki/Light_pillar">Sun pillar (with more photos) from Wikipedia</a><br /><br />The best book on this sort of subject is: <a href="http://www.amazon.com/gp/product/0486201961/ref=as_li_tf_tl?ie=UTF8&tag=gurnjour-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0486201961">The Nature of Light and Colour in the Open Air (Dover Books on Earth Sciences)</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=as2&o=1&a=0486201961" style="border: none !important; margin: 0px !important;" width="1" /><br /><div><br /></div>

Sun Pillar

We saw a good sun pillar last night, though my photo didn't come out as well as this one from the web. A "sun pillar" or ...

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Slit-Scan Video

<iframe allowfullscreen="allowfullscreen" frameborder="0" height="315" src="http://www.youtube.com/embed/NSesvu_uqLo" width="420"></iframe><br />(<a href="http://www.youtube.com/watch?feature=player_embedded&v=NSesvu_uqLo">Link to YouTube video</a>) Slit-scan video transforms everyday scenes by elongating, compressing, and twisting elements into trippy dreamscapes. This one was made with <a href="https://itunes.apple.com/us/app/slit-scan-movie-maker/id493342965?mt=12">an inexpensive Mac app</a>.<br /><br />Kamil Sladek explains how it works on <a href="http://gizmodo.com/5923614/this-slit+scan-video-will-break-your-brain">Gizmodo</a>:<br /><br /><blockquote class="tr_bq">You can make your own slit camera out of any video capable digital camera with a regular sensor and a regular lens. All you need to do is the following:<br />1. record a video of your action<br />2. extract each frame as an individual image (the opposite to what you would do for a time lapse)<br />3. extract a vertical single pixel wide line from each image (for example a line from the center)<br />4. stack those lines horizontally from left to right to form an actual "slit scan" image<br />This can be automated by tools like e.g. I<a href="http://www.imagemagick.org/script/index.php">mageMagick</a> and the longer your initial video was, the wider your image will be. In fact, the width of your slit scan image will have exactly the same amount of pixels as your initial video's frame number.<br />Now, to go one step further you can proceed for all the other vertical lines of your images and create one slit scan image for each particular set of vertical lines. This will give you a set of as many slit scan images as your initial video was wide in pixels. Combining that set of slit scan images to a video (this time exactly as in a time lapse) your result can look like this.</blockquote><a href="http://boingboing.net/2013/01/02/beautifully-strange-slit-scan.html">Via BoingBoing</a>

Slit-Scan Video

( Link to YouTube video ) Slit-scan video transforms everyday scenes by elongating, compressing, and twisting elements into trippy dreamscap...

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Reality vs. Screen Illusion

<a href="http://www.imdb.com/name/nm0499215/">Rob Legato</a> creates visual effects for big-budget movies.<br /><br /><iframe allowfullscreen="allowfullscreen" frameborder="0" height="259" src="http://www.youtube.com/embed/luoKOkTxOtU" width="460"></iframe><br />(<a href="http://www.youtube.com/watch?v=luoKOkTxOtU&feature=g-vrec">Video link</a>) In this TED talk, he shares how he created effects sequences for Apollo 13, Titanic, and Hugo. In the first two cases, actual documentary film footage exists of some of the scenes he was visualizing. The real footage served as a reality check against the cinematic invention.<br /><br />One of the surprising revelations is that our sense of what looks real is greatly influenced by the emotional processes of our memories, which reorder reality into a composite fiction.<br /><br />That emotionally tinged version of reality is what moviemakers need to bring to life if they want to create convincing illusions. The same general principle applies to painting. Often it's necessary to go beyond optical or photographic realism in order to achieve psychological realism. It's the difference between mere accuracy and true believability.<br />------<br /><a href="http://www.youtube.com/watch?v=luoKOkTxOtU&feature=g-vrec">Rob Legato on TED: The Art of Creating Awe</a>

Reality vs. Screen Illusion

Rob Legato creates visual effects for big-budget movies. ( Video link ) In this TED talk, he shares how he created effects sequences for Ap...

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Scientist approaches a lake of lava

<iframe allowfullscreen="" frameborder="0" height="295" src="http://www.youtube.com/embed/egEGaBXG3Kg" width="480"></iframe><br />(<a href="http://youtu.be/egEGaBXG3Kg">Video link</a>) In this BBC video, a scientist takes a big risk to gather a sample from a lake of lava, while a colleague watches nervously from safer ground.<br />via <a href="http://boingboing.net/2012/06/08/scientists-risk-their-lives-to.html">BoingBoing </a><br />

Scientist approaches a lake of lava

( Video link ) In this BBC video, a scientist takes a big risk to gather a sample from a lake of lava, while a colleague watches nervously f...

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Mammatus Clouds

Before the big thunderstorm arrived last Tuesday night, I sat outside and sketched some strange cloud formations.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgktK3ydPiv8zdqoU5GmEtygoWt6eNJPrZwovo0MCJPUPrHFaYMy_cHVOOuB4blSZNKJWPEOGXHiuDwxDWLyTd7p6ik1BqN8INurJ0k9DQG-stQi-_cvawLErCdzT3yQNSdefCIe90eOGo/s1600/Cloud+Effect.Mammatus.sm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="247" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgktK3ydPiv8zdqoU5GmEtygoWt6eNJPrZwovo0MCJPUPrHFaYMy_cHVOOuB4blSZNKJWPEOGXHiuDwxDWLyTd7p6ik1BqN8INurJ0k9DQG-stQi-_cvawLErCdzT3yQNSdefCIe90eOGo/s400/Cloud+Effect.Mammatus.sm.jpg" width="400" /></a></div><br />They're called mammatus clouds, named so because their pendulous forms resemble an animal's udder or a woman's breasts. They are found at the base of anvil clouds, the giant cumulonimbus clouds that generate extreme thunderstorms.<br /><br />As I made this quick notation with my water brushes, the wind whipped the treetops. The clouds swirled and turned green. Big raindrops started falling around me. I folded up my sketch gear and retreated indoors. Hail pounded the deck outside. Lightning flashed, then thunder. Suddenly the electric power died and stayed out for several hours.<br /><br />I finished the sketch by the light of a kerosene lantern.<br /><br /><a href="http://en.wikipedia.org/wiki/Mammatus_cloud">Mammatus clouds on Wikipedia</a>

Mammatus Clouds

Before the big thunderstorm arrived last Tuesday night, I sat outside and sketched some strange cloud formations. They're called mammatu...

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Iceberg flipping over

<iframe allowfullscreen="" frameborder="0" height="295" src="http://www.youtube.com/embed/Sh271FAVZ0o" width="480"></iframe><br />An iceberg gets top-heavy and gracefully turns over. The berg calved from Argentina's Uppsala glacier.<br />---<br />via <a href="http://bestofyoutube.com/">Best of YouTube</a>

Iceberg flipping over

An iceberg gets top-heavy and gracefully turns over. The berg calved from Argentina's Uppsala glacier. --- via Best of YouTube

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Visual Effects on "Boardwalk Empire"

<div class="p1"><a href="http://www.brainstorm-digital.com/">Brainstorm Digital </a>created this video of visual effects breakdowns to show all the layers of elements that go into reconstructing a historical world on film. </div><div class="p2"><br /></div><div class="p2"></div><div class="p1"><iframe allowfullscreen="" frameborder="0" height="295" src="http://www.youtube.com/embed/aFHKwaW4Um8" width="450"></iframe><br />It's a good demonstration of the Emmy-award winning artistry of the people who work in <a href="http://en.wikipedia.org/wiki/Compositing">compositing</a>, an often-overlooked part of the visual effects industry that involves sophisticated judgments about edges, light, and color.</div><div class="p1"><a href="http://www.youtube.com/watch?v=aFHKwaW4Um8&feature=player_embedded">Direct link to video </a></div><div><br /></div>

Visual Effects on "Boardwalk Empire"

Brainstorm Digital created this video of visual effects breakdowns to show all the layers of elements that go into reconstructing a historic...

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Mountain Shadows

No, it's not Sauron reaching across from Mount Doom. It's just the shadow of Mount Rainier in the northwestern U.S., cast across the underside of the clouds at sunrise.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9YBl7YofIMIynmUbDHqvvBGC9V_TnDCZthzcR9hx3B3L6sH4YHWkKeaD6gv7WuDoR6gNNgU8z6bQndGELn_74092QvCYkhesTH5qVzNOQiN2WFlIbDOAQGX60RscPi85NNGMVaR9yoMo/s1600/Cast+Shadow+from+Mountain.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="335" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9YBl7YofIMIynmUbDHqvvBGC9V_TnDCZthzcR9hx3B3L6sH4YHWkKeaD6gv7WuDoR6gNNgU8z6bQndGELn_74092QvCYkhesTH5qVzNOQiN2WFlIbDOAQGX60RscPi85NNGMVaR9yoMo/s400/Cast+Shadow+from+Mountain.jpg" width="400" /></a></div>At the brief moment of sunrise and sunset, the rays of sun, peeking past the edge of the curving earth, can shine upward toward a horizontal deck of stratus or altostratus clouds, lighting them from below. If a mountain nearly bumps its head on that deck of clouds, it can cast a shadow across it. As with<a href="http://gurneyjourney.blogspot.com/2008/05/sunbeams.html"> sunbeams</a> and <a href="http://www.blogger.com/%20http://gurneyjourney.blogspot.com/2009/12/shadowbeams.html">shadowbeams</a>, the lines of the shadow converge back to the sun's position.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWxQfQ0030L_AALPax0klzZ2__iKlPg0IDZjMI4Jd5L_iwSQC8hb0HErK1sQMsSzRLHaLR12B6JZGVKauszIkmmCgS0fS6K-xb_1ZyNZFhaYFL1w4UTyhPAhYPd5Rpxi1zD9YQy3cdxB0/s1600/Mountain+Shadow.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWxQfQ0030L_AALPax0klzZ2__iKlPg0IDZjMI4Jd5L_iwSQC8hb0HErK1sQMsSzRLHaLR12B6JZGVKauszIkmmCgS0fS6K-xb_1ZyNZFhaYFL1w4UTyhPAhYPd5Rpxi1zD9YQy3cdxB0/s400/Mountain+Shadow.jpg" width="400" /></a><br />Seen from the top of Mount Rainier, facing away from the sun at sunset, the cast shadow looks triangular. That triangular shape is not the mountain profile you're seeing, but, again, it's the lines of perspective of the edges of the broad mass of shadowed air running back to infinity through lighter illuminated vapor.<br />-----<br /><i>On Halloween, Monday, October 31, from 11-12:30, <a href="http://www.ccad.edu/events-2011/va-gurney">I'll be lecturing </a>on color and light at the Canzani Center Auditorium at the Columbus College of Art and Design in Ohio. It's free and open to the public.</i><br /><br /><b>Links and Credits</b><br /><a href="http://www.geekologie.com/2011/10/sky-shadows-mt-rainier-at-sunrise-castin.php">More photos of Rainier casting shadows at Geekologie </a><br />The second photo of the mountain shadow is by<a href="http://www.drdale.com/"> Dale Ireland</a> from <a href="http://www.atoptics.co.uk/atoptics/mtshad.htm">Atmospheric Optics</a><br />Thanks, <a href="http://www.chrisvosters.be/">Chris Vosters</a><br /><br />Previously on GurneyJourney:<br /><a href="http://gurneyjourney.blogspot.com/2011/06/reflected-sunbeams.html">Reflected Sunbeams</a><br /><a href="http://gurneyjourney.blogspot.com/2009/12/shadowbeams.html">Shadowbeams</a><br /><a href="http://gurneyjourney.blogspot.com/2008/05/sunbeams.html">Sunbeams</a>

Mountain Shadows

No, it's not Sauron reaching across from Mount Doom. It's just the shadow of Mount Rainier in the northwestern U.S., cast across the...

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Mini Metropolis

Have a look at “Miniature City Shanghai,” a film of real urban life shot in time lapse and tilt-shift photography. (For feed readers here's a <a href="http://www.youtube.com/watch?v=ypb-4J24HwI">direct link to the video</a>.)<br /><br /><iframe allowfullscreen="" frameborder="0" height="290" src="http://www.youtube.com/embed/ypb-4J24HwI" width="480"></iframe> <br />For those who aren’t familiar with it, tilt-shift photography creates the impression of the shallow depth of field in actual large scale scenes. Since we’re accustomed to experience shallow depth of field and fast movement only with small scale scenes, it’s very hard to overcome the impression that we’re looking at frenetic miniatures.<br /><br />Now try watching Chris Burden’s “Metropolis II,” (<a href="http://www.youtube.com/watch?v=_UQ2vqFJvpA">direct link to video</a>) an ambitious kinetic model representing the rhythms of urban life. http://www.youtube.com/watch?v=llacDdn5yIE&feature=player_embedded<br /><iframe allowfullscreen="" frameborder="0" height="290" src="http://www.youtube.com/embed/llacDdn5yIE" width="480"></iframe><br /><br /><br />The macro and micro worlds seem to meet in the middle.<br /><br /><br /><a href="http://en.wikipedia.org/wiki/Tilt-shift_photography">Wikipedia on Tilt Shift photography</a><br /><a href="http://www.amazon.com/Elements-Photography-Understanding-Creating-Sophisticated/dp/0240809424?ie=UTF8&tag=gurnjour-20&link_code=btl&camp=213689&creative=392969" target="_blank">Book: The Elements of Photography: Understanding and Creating Sophisticated Images</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=btl&camp=213689&creative=392969&o=1&a=0240809424" style="border: medium none ! important; margin: 0px ! important; padding: 0px ! important;" width="1" />

Mini Metropolis

Have a look at “Miniature City Shanghai,” a film of real urban life shot in time lapse and tilt-shift photography. (For feed readers here...

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Moonbows in Waterfalls

Not all rainbows occur on rainy days. Rainbows can also form in the mist at the base of waterfalls, such as those  at Yosemite Park in California. They occur not only in the daytime, but also at night, with a full moon at your back. <br /><br /><iframe allowfullscreen="" frameborder="0" height="290" src="http://www.youtube.com/embed/_68ytOYnTvs" width="480"></iframe><br />Nocturnal rainbows form in the same way as daytime rainbows: by means of light reflecting and refracting in droplets of water. At night they’re sometimes called “lunar rainbows” or “moonbows.” In this time lapse video, look for the reversed secondary rainbows at 2:40 and 3:00.<br /><br /><a href="http://www.youtube.com/watch?v=_68ytOYnTvs">Direct link to “Yosemite Nature Notes’ video. </a><br /><a href="http://www.amazon.com/Nature-Light-Colour-Dover-Sciences/dp/0486201961?ie=UTF8&tag=gurnjour-20&link_code=btl&camp=213689&creative=392969" target="_blank">The Nature of Light and Colour in the Open Air (Dover Books on Earth Sciences)</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=btl&camp=213689&creative=392969&o=1&a=0486201961" style="border: medium none ! important; margin: 0px ! important; padding: 0px ! important;" width="1" /><br /><a href="http://www.amazon.com/Color-Light-Guide-Realist-Painter/dp/0740797719?ie=UTF8&tag=gurnjour-20&link_code=btl&camp=213689&creative=392969" target="_blank">Color and Light: A Guide for the Realist Painter</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=btl&camp=213689&creative=392969&o=1&a=0740797719" style="border: medium none ! important; margin: 0px ! important; padding: 0px ! important;" width="1" /><br />Thanks, David<br />

Moonbows in Waterfalls

Not all rainbows occur on rainy days. Rainbows can also form in the mist at the base of waterfalls, such as those  at Yosemite Park in Calif...

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Explaining Summer Solstice

<iframe allowfullscreen="" frameborder="0" height="290" src="http://www.youtube.com/embed/s_NN8pZxTP8" width="480"></iframe><br />Summer solstice comes to the northern hemisphere on June 21 at 1:16 P.M. Eastern time. Here's a clear explanation of the sun's behavior in relation to the tilted axis of Earth.<br /><a href="http://www.youtube.com/watch?v=s_NN8pZxTP8&feature=feedu" rel="nofollow" target="_blank"><span class="yshortcuts" id="lw_1308406530_0">Direct link to YouTube video</span></a><br /><br />Thanks, <a href="http://www.michaelking.ca/">Michael</a>

Explaining Summer Solstice

Summer solstice comes to the northern hemisphere on June 21 at 1:16 P.M. Eastern time. Here's a clear explanation of the sun's behav...

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Cloud Streets

<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNQxvtdAHVs3sWeEVcpN5TP65Zlh2_oIdWgIpZCX08ijfbD5FEq_yvel0lpfkfhdwPzAWfse28_cFWMmNXiGxO3R8PlBZ-A2gz4vAvDB1vm0bg5LyI-aqo_JbjC8hazjYcQHfp4YETYyY/s1600/Cloud+Streets.PNG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"></a>Cloud streets are parallel rows of cumulus clouds that line up in the direction of a steady wind.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgInZfcbDMiMevElb42aDQMK5vRypje6OpkSPtfjzrStaalRoklvHZNfwXxSsZIkX5TIY4KxVsM6cYt3804nDycGQ6cysarKEMog9DlBzZ3_LDaKxs3GCCuTH5UFh044HoyrPiY9ocaLHs/s1600/Cloud_streets.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgInZfcbDMiMevElb42aDQMK5vRypje6OpkSPtfjzrStaalRoklvHZNfwXxSsZIkX5TIY4KxVsM6cYt3804nDycGQ6cysarKEMog9DlBzZ3_LDaKxs3GCCuTH5UFh044HoyrPiY9ocaLHs/s400/Cloud_streets.jpg" width="400" /></a><br />The lines are typically about five miles apart, with clear sky between, and they can extend for hundreds of miles. <br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNQxvtdAHVs3sWeEVcpN5TP65Zlh2_oIdWgIpZCX08ijfbD5FEq_yvel0lpfkfhdwPzAWfse28_cFWMmNXiGxO3R8PlBZ-A2gz4vAvDB1vm0bg5LyI-aqo_JbjC8hazjYcQHfp4YETYyY/s1600/Cloud+Streets.PNG" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNQxvtdAHVs3sWeEVcpN5TP65Zlh2_oIdWgIpZCX08ijfbD5FEq_yvel0lpfkfhdwPzAWfse28_cFWMmNXiGxO3R8PlBZ-A2gz4vAvDB1vm0bg5LyI-aqo_JbjC8hazjYcQHfp4YETYyY/s1600/Cloud+Streets.PNG" /></a>Also called "horizontal convective rolls," they often form over flat country in spring or summer when the wind is blowing beneath an inversion layer. As the wind travels under that layer, it divides into a series of counterrotating cells. Where the air in two adjacent cells lifts upward, a line of clouds forms, and where they join to spin downward, clear air prevails. <br /><br />Glider pilots can stay aloft for miles by following cloud streets. <br /><br /><a href="http://en.wikipedia.org/wiki/Horizontal_convective_rolls">Wikipedia on Horizontal Convective Rolls</a><br /><a href="http://www.weather.com/blog/weather/archive/200806.html">Photo by Stu Ostro from Weather.com </a>

Cloud Streets

Cloud streets are parallel rows of cumulus clouds that line up in the direction of a steady wind. The lines are typically about five miles a...

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Reflected Sunbeams

<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2KhwWblJKjwl019UoXMISKPV5UJkvGkD_VNgingBT2TIAg3j12y756zTNFKiNAD1HH56l8Qj9ed_OtftaNRkPdft72jfiVtEaxhA75N3UktcQga25jlldD9NnlLpT97sS6Ra5QyDXJ5M/s1600/Church.Sunset.Jamaica.1865.sm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"></a>When sunbeams reflect off a smooth lake or sea, they radiate upward. The perspective lines of the parallel rays appear to vanish a point well below the horizon, but actually the sun still hasn’t set.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDb4cJlfy-arLxIGOfirvfxAmHjTVcBxKUKGzLR_Rm_HvzGApc2HgVtCxLLAJdMDBJ4onaSeOOPwG49tP9NsSnU139TgYbxCr5pHH9zxBx_H6cZStIbdOhWNr4atKxj-qBNBajJSAw7a4/s1600/Reflected_Sunbeams.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDb4cJlfy-arLxIGOfirvfxAmHjTVcBxKUKGzLR_Rm_HvzGApc2HgVtCxLLAJdMDBJ4onaSeOOPwG49tP9NsSnU139TgYbxCr5pHH9zxBx_H6cZStIbdOhWNr4atKxj-qBNBajJSAw7a4/s400/Reflected_Sunbeams.jpg" width="400" /></a><br />These reflected sunbeams, or "inverted crepuscular rays", occur often toward the end of the day, not long before sunset. The rays show up best when there’s a dark band of clouds behind them.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2KhwWblJKjwl019UoXMISKPV5UJkvGkD_VNgingBT2TIAg3j12y756zTNFKiNAD1HH56l8Qj9ed_OtftaNRkPdft72jfiVtEaxhA75N3UktcQga25jlldD9NnlLpT97sS6Ra5QyDXJ5M/s1600/Church.Sunset.Jamaica.1865.sm.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2KhwWblJKjwl019UoXMISKPV5UJkvGkD_VNgingBT2TIAg3j12y756zTNFKiNAD1HH56l8Qj9ed_OtftaNRkPdft72jfiVtEaxhA75N3UktcQga25jlldD9NnlLpT97sS6Ra5QyDXJ5M/s400/Church.Sunset.Jamaica.1865.sm.jpg" width="400" /></a><br />During his sketching sojourn to Jamaica, Frederic Church captured the effect in this plein air painting.<br /><br /><a href="http://www.antiquesandfineart.com/articles/article.cfm?request=969">More on Frederic Church in Jamaica</a><br />More on sunbeams in <a href="http://www.amazon.com/Color-Light-Guide-Realist-Painter/dp/0740797719?ie=UTF8&tag=gurnjour-20&link_code=btl&camp=213689&creative=392969" target="_blank">Color and Light: A Guide for the Realist Painter</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=btl&camp=213689&creative=392969&o=1&a=0740797719" style="border: medium none ! important; margin: 0px ! important; padding: 0px ! important;" width="1" />

Reflected Sunbeams

When sunbeams reflect off a smooth lake or sea, they radiate upward. The perspective lines of the parallel rays appear to vanish a point wel...

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Reflectivity and viewing angle

<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG69UxmxO38IEQc70HPdowysFHh-QxYWnl_61iChM2zvi7hXBgYJJYmqd5GnHkySodvl3glJKtKbNOQ51NktnhsDYa0pRlHsNeDWOPfXnpLPXwHfw0XHL1oxjvdziIA-UM3chTj_UTF7o/s1600/Reflective_Surfaces.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"></a>Smooth surfaces are more reflective when you look at them at shallow angles.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG69UxmxO38IEQc70HPdowysFHh-QxYWnl_61iChM2zvi7hXBgYJJYmqd5GnHkySodvl3glJKtKbNOQ51NktnhsDYa0pRlHsNeDWOPfXnpLPXwHfw0XHL1oxjvdziIA-UM3chTj_UTF7o/s1600/Reflective_Surfaces.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="281" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG69UxmxO38IEQc70HPdowysFHh-QxYWnl_61iChM2zvi7hXBgYJJYmqd5GnHkySodvl3glJKtKbNOQ51NktnhsDYa0pRlHsNeDWOPfXnpLPXwHfw0XHL1oxjvdziIA-UM3chTj_UTF7o/s400/Reflective_Surfaces.JPG" width="400" /></a><br />You can see this subtle phenomenon best by looking at cars in an open parking lot. Note how the foreshortened plane on the left is highly specular, or mirrorlike, reflecting the scene beyond with a wide range of values.<br /><br />The back window and tailgate do not reflect the sky or the surrounding cars as brightly.<br /><br />In previous posts, we’ve seen a related phenomenon with smooth water surfaces, which also become more reflective at grazing angles of incidence. In the case of a transparent fluid surface like water, light that is not reflected is refracted beneath the surface. <br /><br />A smooth solid surface like a painted car or a pool ball or an apple is generally a blend of specular and diffuse reflection.<br /><br />But even surfaces that we think of as diffuse reflectors, such as ordinary paper, can be remarkably specular at shallow angles. Hold up a piece of paper at an extremely shallow angle to your eye, so that you’re sighting right along the surface of the paper. If you have bold light and dark lines above that surface (such as the mullions on a window), the paper will behave almost like a mirror, reflecting a fairly clear image of the scene beyond. (Good party trick.)<br />-------<br />Thanks, <a href="http://en.wikipedia.org/wiki/Kevin_Bjorke">Kevin Bjorke</a>, for telling me about this.   <br /><br />More on such things in "<a href="http://www.amazon.com/Color-Light-Guide-Realist-Painter/dp/0740797719?ie=UTF8&tag=gurnjour-20&link_code=btl&camp=213689&creative=392969" target="_blank">Color and Light: A Guide for the Realist Painter</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=gurnjour-20&l=btl&camp=213689&creative=392969&o=1&a=0740797719" style="border: medium none ! important; margin: 0px ! important; padding: 0px ! important;" width="1" />"<br /><br />Related previous posts on GJ:<br /><a href="http://gurneyjourney.blogspot.com/2011/03/eschers-three-worlds.html">Escher’s Three Worlds </a><br /><a href="http://gurneyjourney.blogspot.com/2008/08/color-in-mountain-streams.html">Color in Mountain Streams</a><br /><a href="http://gurneyjourney.blogspot.com/2008/03/transparency-of-water.html">Transparency of Water</a><br /><a href="http://gurneyjourney.blogspot.com/2010/12/specular-and-diffuse-reflection.html">Specular and Diffuse Reflection</a>

Reflectivity and viewing angle

Smooth surfaces are more reflective when you look at them at shallow angles. You can see this subtle phenomenon best by looking at cars in a...

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