Category Archives: shadows and rays
The situation shown in the picture is often misinterpreted (Photo taken by Anja Hoff on 22-08-2012). Most people think that the shadow of the plane and the contrail cast on the thin cirrostratus cloud sheet must lay higher than the plane itself. This seems obvious, since the shadows are higher than the objects producing them. The low standing sun leads one to this conclusion – it is shown in the upper sketch:
The sun is perceived as low standing – lower than the clouds. The shadows, necessarily on the other side of the shadowing object, reach higher in the sky, and the illusion is perfect: the shadows must project upwards. But the actual circumstances are quite different. For any observer in the plane, the sun is above the same high over the horizon than it is for the observer on the surface. If he would see the shadow of his own plane, this would be underneath of him and the plane projecting towards the surface of the Earth.
The ground bound observer is a victim of the everyday perception. For him, the atmosphere is a three-dimensional volume, and the sun is located in it. But all the rays of the sun enter and cross the atmosphere parallel. This is shown in the lower sketch. From this it is evident, that the shadows can only be lower than the plane. Even at sunset/sunrise the shadows would not be cast above the plane. The single possibility, which I have had the opportunity to see once, is that the plane heads directly towards the sun eclipsing its own contrail. Another very interesting possibility is the eclipsing of the contrail from one side of the plane by the other, so that the one towards the sun is whitish-bright and the other grayish-dark – indeed a very spectacular view!
The two pictures below are from a series and can be used as a stereoscopic pair. If you look at the pair with crossed view, you will get a 3D impression of the scene – and you will notice that the top of the shadow peaks are much nearer to you than the clouds originating them.
Author: Christoph Gerber, Heidelberg, Germany
On November 16, 2010, Hans Juergen Heyen had a rather “spooky” day in Düsseldorf. “A short time after noon I took a walk along the river Rhine and wanted to shoot some photographs. In the beginning, the sky was completely clear except some mist, but at about 14 hours some ragged clouds came up which lowered down to about 100 metres above the ground. The clouds were followed by a mixture of fog, sunshine and clouds which in this area (Lower Rhine region, about 45 metres above sea level) is very uncommon. Also the frequent change between a nearly closed layer of stratus clouds and blue sky was rather strange.
A great help for evaluating the situation was the Rheinturm, a TV tower which is about 240 metres high and has a restaurant with an inclined bank of windows at about 180 metres. This tower disappeared and reappeared between the fog and clouds causing some shadow plays and reflections which were rather irritating for the observer. Sometimes even phantoms of the tower appeared. The tower quasi became an actor in this weather phenomenon. Some time ago, I witnessed a similar phenomenon at the same place, which at that time had turned out considerably fainter. But this time, the phenomenon lasted for about two hours. It just seemed as if the Cllerk of the Weather had been sitting in a pub in Düsseldorf Altstadt and lost the control about his remote weather control while drinking the famous Altbier, a very popular kind of beer in Düsseldorf. For people interested in weather phenomena, it was a really gorgeous afternoon”.
Two main phenomena were visible: When the sun was beside the tower, it caused reflections in the bank of windows around the tower restaurant projecting shadow rays onto the wall of fog. This was a kind of reflected anticrepuscular rays (1-2-3-4).
Later, when the sun was almost behind the tower, another strange shadow play became visible. Contrary to what is usual, the shadow of the tower was not on the side of the tower which points away from the sun, but in direction towards the sun. This was because the observer was now postitioned in the diffuse shadow of the tower. Normally he should now see the shadow behind himself on the ground. But as the droplets of the wafts of mist formed a kind of screen in front of and below the top of the tower, the shadow of the tower was now displayed on the fog.
Sometimes the shadow was displayed on several layers of fog forming multiple images [1-2].
When the sun is positioned directly behind the tower, only the upward projection of the tower top is visible, being cast upon ragged clouds above the tower by the low autumn sun. More pictures 1-2-3-4-5-6
In the evening of April 18, 2012, I observed some light rays from 2962 metres high Mt Zugspitze . These rays did not emanate from the sun which at the moment I took the photograph was above the rays under the cloud layer. And there were bright reflections of the sun on the ground indicating that there must have been a large lake .
Taking a look at the map I realized that Lake Constance was in that direction, but there were no reports that it is visible from Mt Zugspitze. Just the bright reflections of sunlight made it possible to recognize it. The surface of 536 square kilometres large Lake Constance, the third largest lake in Europe, reflected the sunlight scattering it towards me. The shadows of the mountains between me and Lake Constance were projected upon the cloud layer from below creating this wonderful natural spectacle.
A similar observation can be found here: Reflected sunray
Author: Claudia Hinz, Germany
“On the afternoon of 16th November I noticed a dark ring around the sun outside of an aureole. However, the effect could be catched better with the naked eye than the photographs assume.” (2)
“I took some picture in close succession, but none of them shows the ring. Conspicuously, the ring was distinguished by high regularity and evenness. Subsequent enhancing of the contrast let the dark ring become visible clearly on these pictures.”
Quite often, you can spot clouds moving in front of the sun. With a little luck and a cloud layer, that isn’t too thick, beautiful halation and aureoles can be seen at these conditions.
Since a cloud act as an obstacle, it causes a shadow. Apriori, this shadow is invisible to the observer. But if the shadow is projected onto a lower layer of haze, the shadow gets visible in the haze.
Hence, the example above generates a dark ring around the sun, induced by altocumulus cloud shadows on the hazes below.
Time : 16 November 2011
DSLR Camera : Nikon D 3100
Exposure : 1/500 sec, f/22#18mm, F/11, ISO 100
It was the 21st of June in 2010, when I came back from work in the evening and prepared my photo equipment for some time-lapse experiments of the very intensive sunrays currently shining. I was late and just wanted to get one last visual impression from my balcony before walking down to the river and shooting the pictures. What I saw was pretty amazing, so that it took some seconds to get the camera working.
The reflected sunray remained for 50s since my first view. I took 4 pictures of it and made a small animation. The occurrence of that common sunray on the same cloud baseline seems to be at random, due to the fact that the reflected ray moves with reduced speed.
Some discussions revealed that the river itself could not cause the mirror effect, because the surface of running water is too unsettled and not plane enough to produce such a shapely reflection. A calm and wind-protected surface is the harbour basin in a distance of about 3km in the direction of the sun. Further waters in that direction are more distant (>10km).
I kept an eye on comparable situations to get these reflections again, but without success so far. You should be watchful on the following conditions:
- intensive sunrays of course
- low altitude of the sun (to get long distanced rays)
- dark clouds in the short distance (to get the contrasts)
Place : Dresden, Germany
Time : 21 June 2010
DSLR Camera : Canon EOS 1000 D
Exposure : 1/80 sec, f/55mm, F/7.1, ISO 200
Author: Eik Beier, Dresden, Germany
From August 2 to August 16, I was on holiday on the Greek island of Karpathos. Already on the first evening there, on August 2, I was astonished about an intense purple light with crepuscular rays. These purple twilights appeared every evening at about 10 minutes after sunset an were visible for about 10 minutes. This continued over the whole two weeks, except on August 4, when the purple light was only a bit brighter than normal.
The most intense purple twilights occurred on August 9 and 11, when even the water of the Mediterranean Sea turned purple during these twilights.
Between August 9 and August 14, the purple twilight was followed by an intense, dark red glow above the cloudless western horizon, which was visible until about 35 minutes after sunset. Just before sunset, the sunlight illuminated the Kali Limni, the highest mountain of Karpathos island (1215m) in a rose and violet shade, causing a kind of alpenglow which was visible from the beach.
As I learned after my return at home, these unusual twilight effects were caused by volcanic clouds emitted by Mt. Nabro in Eritrea in June and July.
Author: Peter Krämer, Bochum, Germany
In August 2011 I noticed colourful twilights with purple light and venus belt in France and Germany during some days. These intense sunsets resulted from volcanic aerosols in the atmosphere.
On August 12, 2011 I could take some photos of the sunset with the purple light near the Gorges du Verdon (Provence/France). Additionally, there were beautiful crepuscular rays in the sky (photo on top).
Back in Germany I could photograph also such fantastic sunsets with crepuscular rays and anticrepuscular rays.
Author: Daniel Eggert, Augsburg, Germany
In the morning of November 11, 2010, Anke Morbitzer from Gladbeck, Germany could enjoy the alpenglow from above during a flight from Milan over the Bern and Pennine Alps. Especially impressive were the shadows of the mountains being projected upward into the haze. Just before, also the upcoming twilight with its impressive colours had been very exciting.
We most always notice crepuscular rays as fingers of light and darkness that stretch toward us from the horizon.
However, on occasion it’s possible to observe them “sideways”. The photo above offering such a view was taken from Kämpfelbach (Germany), at sunset, as the cumulonimbus anvil at far right effectively blocked sunlight from reaching the low hills in the distance – middle and left.
Note that the wedge-shaped, blue-gray shadow from this towering cloud extends all of the way to the antisolar point. Photo taken on April 22, 2011
Author: Michael Großmann, Kämpfelbach, Germany
Sometimes it may happen that there are several cirrus layers above a building thunderstorm cloud. Only when the cumulus cloud has grown to a high level breaking through these cirrus layers, its top casts a shadow upon the cirrus layer.
If there are several cirrus layers, this multiple projection is caused by the perspective effect.
Also this photograph is rather old, it is still very impressive.
Camera: Nikon D40x; focus lenght: 55mm; exposure-time: 1/500 sec.; aperture: F/11; Date: 05.09.2009
Author: Michael Großmann, Kämpfelbach, Germany