Category Archives: air mirages

Green-rimmed cloud at sunrise

Greenrim01

On June 14th, 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 24th, 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.

Greenrim2

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

green_cloud_dips

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

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

Distorted Solar Disk by Smokestack Exhausts

Kovacs1k

The Hungarian observers Attila Kovács and György Répás witnessed an unusual kind of refraction. The temperatures in the exhausts of smokestacks differ widely within a small space, which causes very bizarre distortions of the sun.

Attila reports that such strangely distorted solar disks can be seen almost every day in the exhausts of smokestacks. So it is worth while trying it by yourself to get a live impressions of physics.

Photographs:
   Attila Kovács at the hospital of Eger, November 11, 2014:
   György Répás, smokestack in Budapest, March 29, 2014:

Mirages in front of solar disk

On June 7, 2014, there was an especially interesting sunrise on Mt. Zugspitze. There was not the green flash I expected, but the miraged mountains of the Bavarian Forest showed up in front of the rising solar disk (image series). According to calculations of the position of the rising sun and Ulrich Deuschle´s panorama program the mountains visible in the mirage were probably Mt. Hoher Filzberg (1279 metres) and Mt. Sulzriegel (1260 metres), which are 252 kilometres away. The mirages were only visible in front of the solar disk, apart from that visibility was only at 60 kilometres, which is not enough by far for seeing the Bavarian Forest from here.

Author: Claudia Hinz

Air mirage over Munich

In clear air, the Alps are visible from Munich. In the morning of October 18, 2012, Frank Sievers observed this superior mirage of the Alps from the roof of a house behind the Perlach heat and power station. It was probably caused by layers of air of different temperature generated by the power station, which refract the light at different angles to the observer´s eye.


One day later, in the morning of October 19, 2012, the unusual mirage was visible again. This photo taken Stefan Rubach from the same Rooftop.

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: 12345

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 (123).

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

Mountain Mirage in Germany

In December 2006, some very prominent inversions formed in Germany. On two days mirages were observed along these inversion layers.

In the morning of December 15, 2006, Rüdiger Manig could see the miraged Fichtelgebirge from the weather station at Neuhaus am Rennweg in Thuringia, which was situated directly above a sea of clouds when he made his observation. The distance between the Fichtelgebirge and Neuhaus am Rennweg is about 70 km. The photograph shows Mt Schneeberg (1053 m) on the left and Mt Ochsenkopf (1023 m) on the right.

On December 23, 2006, Stephan Rubach saw the Alps main ridge in a distance of more than a hundred km from Mt Grosser Arber (1456 m) in the Bavarian Forest. Also he stood above a sea of clouds when making his observation, and the layers of air of differnent temperatures let the peaks of the Alps grow upwards in an abstractly distorted way.

Winter Mirage in southern Finland

The image was taken by Timo Kuhmonen at last weekend, on Saturday 10th February 2007. Place is near to Helsinki / Finland (Lauttasaari).

Timo was outside on that day hiking and taking some winter weekend photos. He had seen the mirage above frozen sea, distant island was “floating” on the air.

Temperature on that morning at his house in Espoo was -20°C. At the place where photo was taken, temperature was higher. Propably there has been enough of temperature differences in the air layers to produce this “winter mirage”.