Green-rimmed cloud at sunrise

On June 14^th, 2014, I could observe green flamelets at the upper rim of an altocumulus cloud from Mt. Zugspitze (2963 m above sea level). The cloud was located left from the rising sun, and the phenomenon lasted from two minutes before the visible sunrise until shortly after it. At the moment of the astronomical sunrise the green flamelets at the cloud vanished. Additionally, green and blue rims appeared at the sun’s disk (see pictures  1 – 2).

I already observed a similar phenomenon a few seconds after sunset on September 24^th, 2013, from Mt. Zugspitze. However, I could only take a single photograph of it. As there were seemingly no other reports about green cloud rims I decided to let the matter rest at that time. It was only after the second occurrence that I re-visited the case of the older observation.

When doing a new search for similar reports I encountered an observation from by Robert Wagner, January 7^th, 2008, who also recorded green cloud rims during sunset on La Palma (2136 m above sea level).

No other documented observations could be found on the internet so far.

We cannot offer a complete explanation yet. It may be that the cloud edge, when illuminated from behind, acts as a separate light source and the green flamelets are then caused by the refractive dispersion of a weak mirage effect. This is consistent with the presence of blue and green rims at the sun, which indeed have been observed in all three cases. Furthermore, all observations were carried out from high mountains, from where the true geographic horizon already lies below zero elevation, and even the ordinary elevation shift due to refraction is already pretty high due to the long light path through the atmosphere.

More ideas and reports of similar observations are welcome in any case.

Author: Claudia Hinz

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Edit 21th March, 2017: 

I would like to add a video to this article, in which I was record the green rimmed clouds on the Mt. Fichtelberg/Ore Mountains on 20-12-2016.

Green flash over the North Atlantic Ocean

I am currently working as an astronomy lecturer for a German tour group sailing the Norwegian cost on the Hurtigruten vessel MS Nordnorge. On October 8, around sunset we crossed the Vestfjord a stretch of open sea between the Norwegian mainland and the Lofoten islands. Since I expected to see a green flash, I prepared everything to capture the phenomenon.

I was not disappointed. Through my 600 mm telephoto lens I could clearly see the green an blue flash. Closer inspection of the images afterwards also revealed that I also manage to capture a purple flash in the last fractions of a second before the upper limb of the Sun entirely disappeared.

I am attaching a panel which collects crops from the last 30 images in my picture series which show the development of the phenomen over the last 12.66 seconds (according the time stamps created using GPS time). I have also created a very nice gif animation of the event, which you can find (along with additional pictures) on my homepage.

Author: Benjamin Knispel, Hannover, Germany

Bayly`s Beads style sunset

When watching the sun above cold water, you sometimes can observe an unusual phenomenon. The sun does not set as a “ball”, but seems to diverge at the horizon. Sometimes it even appears as a bright horizontal line which adapts a shape reminding of Bayly´s Beads during a total solar eclipse. The last bright beads sometimes disappear only at a few minutes after sunset. This phenomenon was first documented by the British amateur astronomer John Franklin-Adams. He observed the phenomenon several times from board of a ship and attributed it to the swell near the horizon.

Bayly`s Beads style sunset over the Baltic Sea. Photo: Sven Aulenberg, 27.08.2014

Even if it may sound absurd, the conditions above a sea of clouds are similar to those above the ocean. The suface of the moving clouds is undulated, and also the surface of the clouds is cold, just like that of the sea. So the light gets reflected and the light-emitting object (in this case the sun) gets lifted optically. The bright beads then shine throug the gaps of the waves, no matter if they are made of water or of clouds (photo spread).

Bayly`s Beads style sunset over sea of clouds. Photo: Claudia Hinz, 19.02.2015

 

Author: Claudia Hinz

Etruscan Vase during Venus Transit

At sunrise during the transit of Venus on June 6, 2012, there were not only distortions of Sun and Venus visible as well as the Green Flash, but there were also several observations of the so called Etruscan Vase.

As weather forecasts for Germany´s sunniest island, Fehmarn in the Baltic Sea, were most favorable for that day, Jens Hackmann flew there from the bad weather of his home town Bad Mergentheim. Just after sunrise at 4.41 hours, he observed the mirage effects mentioned above not only on Sun and Venus, but also on a passing ship. And only a few moments later the Etruscan Vase phenomenon appeared, an upside-down mirage of the sun which appears in most cases above a water surface (more pics and film).

Thomas Stemmler photographed the transit of Venus at beach on the Baltic Sea near Dahme and could shot mirage effects and the phenomena of Etruscian vase also.

This strange effect is caused by the refraction of sunlight together with a lower mirage and appears when a layer of cold air is positioned over a warm water surface. The lowermost air layer, which is heated up by the warm water, has a lower refraction index than the air at the level of the eyes of the observer. Sunrays hitting this layer in a very sharp angle can be reflected totally. So the observer does not only see light coming directly from the sun, but also light that had been reflected by the warmer and less dense layer of air directly above the water. The rays coming directly from the sun let the sun appear totally normal. But as our brains are not programmed for totally reflected sunrays, they extrapolate them lineally. This makes us see an upside-down reflection of the sun beneath the real sun which changes due to the angle of incidence of the light and thus with the sun elevation.

This phenomenon reminded the science-fiction-author Jules Verne of a paunchy Etruscan Vase standing on a pedestal, so he coined this term for the phenomenon.

Air mirage effects during transit of Venus

On June 06, 2012, the rare constellation of the planet Venus crossing through the solar disk could be observed from the day side of the earth.

When in Germany the sun rose, the Venus transit was already in its final stage. Where the sun passed through differently dense air layers during its rise, the mirage phenomenon was visible, i.e. the sun as well as Venus appeared distorted or as a combination of multiple images. These effects are due to the different bending of the light waves at air layers of varying density. Moreover, an incident ray of light will be reflected at the interface between cool and warm air. When there are more than one of these interfaces, multiple reflection might occur.

Rico Hickmann could even observe the Green Flash during the Venus transit from Dresden: “I was incredible lucky with respect to the weather. Yesterday evening, it was still very cloudy, and after the end of the transit there were again clouds filling the sky. Before sunrise, a light pillar could be seen, that served as a pointer towards the sun. The sunrise over Dresden was spectacular, Green Flashes and disconnected segments… I’m still speechless.” Here are some more incredible pictures from this series: 1–2–3–4–5

Another spectacular image of a triple Venus was obtained by Frank Killich, who observed the Venus transit from the Wolfswarte in the Harz mountains (916 m / 0 °C). The image is a single frame from a HD video file.

Some more and equivalently wonderful observations were reported.  Alexander Haussmann made a Video showing a triple Venus, green segments and distorted Venus passing through different air layers that were responsible for the green segments some seconds before. Further examples of impressive green flashes are the pictures of Andreas Möller, taken in Zinnowitz (photo and and animation as gif or MP4 [better quality]) and Hermann Koberger from Fornach, Austria (1–2–3).

Green an blue flash at sunset behind mountain range

Almost every times when on Mt. Wendelstein the sun is setting behind the main chain of the Alps in very clear air, I can watch the green and the blue flash. These phenomena were especially impressive on February 2, 2011, when the sun sat behind 2962 meters high Mt. Zugspitze, and on March 3 at sunset behind the 1801 meters high Benediktinerwand (series 2).

Author: Claudia Hinz, Brannenburg, Germany

Omega sun

On June 26, 2011, Laslo Segi could photographically record this nice moment. “It looked like a second sun rising from the sea, although the sun was just setting.”(1)

“Some time later I learned that it was a lower mirage, that means that the sky is reflected upwards by a thin layer of warm air above the ground.”

This is caused by air layers of different temperature. At the boundary surface, light is totally reflected causing these phenomena. This phenomenon, however, is called “Omega-sun”, because the shape of the sun is similar to the Greek letter omega.

Photo taken on 26.06.2011 in Croatia/Fazana

Author: Laslo Segi / Michael Großmann, Kämpfelbach, Germany

Fascinating moonrise during an atmospheric inversion

After a bleak low stratus day, I decided to escape from the fog in the evening of the 13th of January 2009. I drove to the nearby Witthoh (Hegaualb, western Lake Constance, Southern Germany). There I wanted to record the rise of the moon – at least I hoped for a clinched moonrise, because of a prevailing atmospheric inversion.

Along the 860-metre-high Witthoh there was still a temperature of -10 degree centigrade. Two kilometers further away and 100 m higher the temperature was just 0 degree centigrade. Consequently, a very remarkable temperature layer existed in this region.
On the pre-calculated time, the moon’s upper margin pushed over the horizon.
What happened afterwards exceeded my boldest dreams. A “bubbling” of the rising moon followed as I had never seen it before.

Three times, approximately half of the rising moon completely detached from the lower half with red lightning.

The moon “boiled” on the upper half and it let vanish red and green rays upwards.

Only after circa 15 minutes, the moon calmed down completely.

Here is one more link of the moonrise as animated GIF file!

Posted by Harald Wochner

Sunset sequence

This sequence of images of the setting sun was taken on September 14th, 2008, from Beverly Beach, Oregon, on an evening when sea mist partly obscured the sun. A vague green colour appeared on the upper edge of only one or two of these images.

Author: Alan Clark, Calgary, Canada

Gree-blue Flash over the Canadian Rockies

This sequence of sunset images was taken from the Canadian prairies, looking ovcr the Rocky Mountains from a distance of about 100 km, in mid-December, 2007. The remaining solar limb shows distinct blue colour following green tints, but the sequence ends with a faint red band, which is probably caused by faint clouds on the horizon.

Author: Alan Clark, Canada