A lot of discussions went on before the SV-Tower was built. The headquarters of the publisher “Süddeutscher Verlag” was originally designed to be a 145 metres high 39-story building, but had to be limited to 100 metres (28 stories) after a popular petition in Munich.
It was built between 2006 and 2008, when in September the SV employees rather unwillingly moved to their unloved new workplace.
There were several discussions on the visual appearance of the new high-rise building. Some considered it as a boring square log, while others admired the special feature of its storefront.
This storefront consists of a straight inward and a prismatic outward glazing. As the individual panes of the outer storefront are inclined to each other, they reflect landscape and sky alternately. So, depending from the incidence of light and the observer´s position, the appearance of the tower changes permanently. The inner glazing is normally not important here.
Already in 2010, a friend showed me an unsharp photograph taken from his mobile phone, which showed sunrays in dispersing fog around the SV Tower. Although I pass the building almost every morning, it took five years until I could experience this phantastic light show myself.
Hoping to be lucky this time, I took my camera with me on my way to work on November 3, 2015. The tour didn´t start very promising, as there was no fog around Munich. But when I reached the fairground east of the city, some fogbanks appeared, which already had started to disperse. Above them, the sun was shining, and so I got more and more excited. Should I really be lucky today?
Short before the end of the A94 motorway, the SV Tower provided a stunning show with its reflected sunrays in the fog. Just a few hundred metres further I took an exit and went back on a road parallel to the motorway. From a parking lot I could watch and photograph the permanently changing sunrays.
Intensity, direction and appearance of the rays constantly changed when I changed my position and the wafts of mist moved. And even the inner glazing played a role now, because the light caroming the straight inner glazing becomes reflected parallely. This caused an effect of “ghost windows” in the fog.
When I started my observation at about 9.50 a.m., the fog was still relatively thick. At about 10.25 a.m., the fog had completely dispersed and the show was over.
Author: Rainer Timm, Munich, Germany
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
After being up at Niagara Falls back in 14 I had to come back for more and wanted to be there when the lights on the Canadian side light up the falls. The night we arrived the light were turned up and got to see some amazing rainbows. The lights would change color and it was a sight to see a rainbow being different colors along its length. In addition to the floodlight bows I also got nice rainbows from natural sunlight and using the super wide angle field of view with my GoPro camera I got nice full circle rainbows. For anyone who is a waterfall or rainbow chaser. Niagara Falls is the place to go and falls are BEST on the Canadian side and this is the perfect bucket list item.
Author: Michael Ellestad, Ohio, USA
Contrails are a result of water vapour, produced as a product of combustion, being ejected from the aircraft engines (→ article)
When a contrail forms near the sun, it’s possible to see a rather beautiful ‘rainbow effect’, as in this example. Such iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. The aerodynamic contrail formed by the reduction of pressure in the air as it moves over the wing. When the pressure of a gas falls, then its temperature also falls (the same principle as is used by your refrigerator). The reduced temperature causes small drops of water to condense, which then may freeze. The (frozen) drops get larger as more water condenses on them. The iridescent colours are sunlight diffracted by millions of water droplets condensed by the airflow over the wings. The droplets all have similar life histories and therefore similar sizes, ideal conditions for iridescence.
The photograph was taken by Ron Smith at around 1300 local on 18 July 2015 at Henstridge, Somerset, UK. The aircraft was flying from East to West and, when first seen, was only producing an intermittent contrail. The iridescent contrail appeared as the aircraft approached a cloud layer just below its flight altitude.
One of nature’s works of art!
Authors: Ron Smith, Somerset, UK and Claudia Hinz, Germany
Sometimes it occurs that small cloud cap forms above a cumulus or cumulonimbus cloud. These caps, wich are similate to a veil, are called pileus (cap) and indicate that the air above the cumulus cloud is very humid. The humidity is near the saturation point, so that a cloud can form. If this cloud cap is near the sun and the glare of the sun is in an ideal case reduced by the cumulus cloud covering the sun, iridescent colours appear in the cloud cap.
The intense colour of a pileus cloud indicates that the water droplets in the cloud are very small and of a uniform size.
Such an iridescent pileus cloud could be observed by Gabriele Schröder on June 6, 2015, at 6.50 P.m. in Schneeberg in the Erz Mountains. The phenomenon appeared in three different parts of the cloud within 10 minutes. Especially interesting is above all the shadow in this picture, which was cast by the lower cumulus cloud and projected upon the clouds. Faint rays can also be seen behind the cloud, indicating that also the surrounding air is very humid.
Still today we have atmospheric phenomena many people have never heard of, know little about or have at least never seen themselves. For me one phenomenon I had never seen until recently are the so-called red sprites. Red sprites are a high atmosphere light phenomenon (also “transient luminous event” or TLE) related to thunderstorms and extend over altitudes between 40 and 100km above ground. They can have various forms, sometimes like carrots or tendrils, often reticulate, sometimes rather bushy. It has been shown that positive lightning is at least correlated to the occurrence of red sprites, probably triggering them under certain conditions as sprites mostly occur a few to several milliseconds after CG+ (cloud-to-ground positive) lightning. Negative cloud-to-ground lightning (CG-) can rarely cause sprites, approximately 99% of sprites are related to CG+-flashes. Positive lightning is a tropospheric type of lightning where an electrical discharge from the positively charged anvil (top) of a thunderstorm to the ground takes place whereas much more common negative lightning originates in the lower part of cumulonimbus clouds. A discharge from the top of a thunderstorm to the ground requires an enormous amount of charge (hundreds or thousands of a Coulomb) so they only make out a small percentage (about 5-10%) of all lightning in thunderstorms and have been found to be more likely to occur in longer-lived dissipating thunderstorms and winter storms (maybe because the tropopause is a few kilometers lower during winter, hence less charge is required for a discharge from the top of a thunderstorm to the ground). The conditions above a thunderstorm, in the stratosphere, mesosphere and ionosphere are also important for the formation of sprites. Yet the exact processes in and around thunderstorms that lead to the occurrence of sprites are still not fully understood. What is certain is that most thunderstorms do never cause sprites. From satellite observations a global sprite occurrence rate of approximately 1 per minute has been derived whereas the tropospheric flash rate is about 3000 times higher: 44 per second on average. Most sprites appear over Mesoscale Convective Systems (MCS) with a cloud top area of more than 100.000km² while above super-cells or air-mass convective storms rarely any sprites are observed, though super-cells can trigger other TLE like e.g. blue jets.
During the night from July 2nd to 3rd, 2015, I was out in the fields near Felmerholz a few kilometers outside of Kiel, Schleswig-Holstein, actually hoping for some noctilucent clouds. These days they can often be seen here throughout the whole night as the sun never goes below approximately -13° altitude. Fortunately they did not appear which seems rather absurd to say. But instead of focusing on the northern horizon I began to center my attention on the thunderstorms at the convergence line moving from the Netherlands through the North Sea towards Denmark and the extreme northwestern Germany at that time. It is not clear if this system can be characterized as MCS, though its sheer size on satellite images allows of that suggestion reaching from the northerly Netherlands and western Germany to northern Denmark. For me it was visible over the northwestern horizon and steadily producing visible tropospheric lightning about 150-200km away.
I decided to try to catch some sprites which I have been trying for years when the conditions seemed good. I was pretty sure it would be impossible to catch them as the moon was shining practically at its fullest and midnight twilight was the other reason I did not really believe in this possibility. Though I had a hope. So to maximize the chances of capturing sprites, which I assumed to be a very faint phenomenon, I thought it would be best to reduce the exposure time and increase aperture and ISO setting to compromise between a short light integration time and image quality. So I started continuously capturing images of the distant thunderstorms at 16mm, 3.2s, f/2.8, ISO3200 on a Canon 7D (APSC) for around two and a half hours. After about 30 minutes I recognized the first, my very first sprite on a picture struggling to believe in what I saw. Not only since there was a sprite visible on the image high above the thunderstorm but I was also puzzled about its brightness and size. I continued to shoot for another two hours, the whole observation period was between 22:25 UT and 0:50 UT. As I continued I found another three sprites on my images. When I later analyzed the raw images on my computer I found three more sprites on the images which were rather small and faint compared to the others seen before.
The first (faint) sprite I captured occurred at 22:37 UT, which is just 12 minutes after I started. The next ones were at 23:03 (bright), 23:18 (bright), 23:26 (bright), 23:29 (faint), 23:35 (bright) and 23:39 UT (faint). True midnight, when the sun is lowest, was at 23:23 UT with a sun altitude of a bit above -13°, so it was barely astronomic twilight. Of course there are some gaps between all images (mostly approx. 0.2s, but sometimes several seconds up to a few minutes due to image revision) so that it is absolutely possible that even more sprites actually did occur. I could not see a single one with the naked eye, though I don’t want to say it wouldn’t have been possible. At least the images suggest, it would have been possible to see and my eyes were not too focused on what happened in the sky.
Remarkably all sprites appeared over the northern part of the squall line, which was approximately 200km away from me. There’s one other observation of the very sprite at 23:03 UT from central Mecklenburg-Vorpommern, which suggests that even much greater distances from a thunderstorm of several hundred kilometers may allow suitable conditions for observing sprites but also smaller distances of just around 100km might be suitable. After about 0 UT (2 am CEST), when no more sprites appeared over the northern part, I tried to capture some over the more southern part, but within an hour, no more sprites could be captured by the camera though the tropospheric lightning activity remained high. I did not change the camera settings during the whole image recording, so if they had occurred they would likely be visible in the images. Of course it is still possible I missed some due to the camera reaction time. But from my observations, I want to make the educated guess that there must have been a difference between the northern and the southern part of the squall line, which certainly was not the frequency of the visible tropospheric lightning but probably the fact that the northern part was indeed dissipating with a slowly decreasing frequency of discharges.
During these two and a half hours I took more than 2000 images to get at least seven sprites. If the sky would have been darker I could have used longer exposures and thus had to take less images but I would say it was definitively worth it.
“Charge transfer and in-cloud structure of large-charge-moment positive lightning strokes in a mesoscale convective system”, Blakeslee et al., 2009, doi:10.1029/2009GL038880
Lang, T. J., W. A. Lyons, S. A. Rutledge, J. D. Meyer, D. R. MacGorman, and S. A. Cummer (2010), Transient luminous events above two mesoscale convective systems: Storm structure and evolution, J. Geophys. Res., 115, A00E22, doi:10.1029/2009JA014500.
Victor P. Pasko, Yoav Yair, Cheng-Ling Kuo. (2012) Lightning Related Transient Luminous Events at High Altitude in the Earth’s Atmosphere: Phenomenology, Mechanisms and Effects. Space Science Reviews 168:1-4, 475-516.
Author: Laura C. Kranich, Kiel, Germany
At 6.35 A.M. on June 25, 2015, I noticed a plane passing through a clear part of the sky without leaving any trace (contrail) behind. Then I observed a beautifully irisating foehn cloud, when suddenly a distrail moved into the cloud dissipating it within two minutes.
Distrail is a short word for dissipation trail. It describes streaky cloud holes caused by airplanes. When a plane flies through or directly above a thin cloud layer, the wake vortices mix the dry air around the cloud into it and the cloud droplets evaporate. This effect is even strengthened by the hot exhausts of the plane, and a clear trail forms behind the plane. Often dust particles in the exhausts act as condensation nuclei making the cloud droplets freeze and form ice crystals. As the saturation vapour pressure above ice is lower than it is above water, the adjacent droplets evaporate. The result is then a white streak of ice clouds between two clear streaks.
Amateur pilots report that the dissipation of clouds also works at small airplanes without jet engines. In this case the propellers stir the air making the cloud dissipate.
Author: Claudia Hinz, Fichtelberg (1215m), Erz mountains, Saxony
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.
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).
Author: Claudia Hinz
Have you ever wondered how many photos of outstanding atmospheric phenomena may exist “out there” without us knowing about them, just because they are not posted on our regular websites, blogs or forums? From time to time, I do Google image search queries on atmospheric optics related subjects to see if something interesting and yet unknown might show up. Some weeks ago, I encountered this way a true rainbow rarity on a Japanese website. The picture had already been publicly accessible for over two years, but went unnoticed by the European or US atmospheric optics community so far. Using the automatic translation function I identified the photographer and contacted him to learn more about his (as of now) unique observation.
Kunihiro Tashima noticed an approaching rain shower on the evening of August 5th, 2012, in the town of Yobuko, Saga prefecture, Kyushu island, Japan (33.54° N, 129.90° E). According to his experience, these showers appear quite regularly after sunny days in the Japanese summer. At 18:24 JST he took the first photographs of a marvellous rainbow display made up from a triple-split primary and an undisturbed secondary (photograph 1, unsharp masked; photograph 2, unsharp masked) from a parking lot. Kunihiro used a Nikon D7000 camera equipped with either a AF-S DX NIKKOR 18-55 mm or a Tokina AT-X 116 PRO DX II 11-16 mm lens at 18 mm and 11 mm focal length, respectively. The sun was located at 9.7° in elevation and 283.8° in azimuth when these pictures were taken.
Within the next minute the shower intensified at his position, so he had to withdraw into his car. Photos taken at 18:25 through the windscreen give the impression that the middle branch had by then already merged with the uppermost one, resulting in a rather broad “traditional” twinned rainbow (photograph 3, unsharp masked). Around 18:32, only an ordinary single primary and a weak secondary were left in front of receding clouds and the blue sky (photograph 4, unsharp masked). At this time, the sun’s position was 8.1° in elevation and 284.9° in azimuth.
Twinned rainbows are nowadays a well-documented phenomenon  and several promising steps have been taken to explain their formation [2, 3]. In one of my earliest reports on simulations of rainbows generated by flattened drops with broad size distributions, I pointed out the idea that also split rainbows with three or four branches might occur at very rare occasions [4, p. 117]. However, up to now, no photographs or clear observation records of such highly exotic rainbow displays have been known to the community. Some old reports of multiple rainbows do exist , but these are difficult to evaluate due to the lack of further details. Hence Kunihiro’s photos provide to my knowledge the first reliable evidence that multi-split (>2) rainbows exist.
A reflection rainbow generated by mirrored sunlight from a horizontal water surface can be excluded as an explanation here, since the angular deviation from the original bow would have to be larger at this solar elevation. Furthermore, the secondary bow remained unaffected by any anomalies, which is a familiar feature seen in many split rainbow displays.
For further analyses it is necessary to assign scattering coordinates (scattering angle and clock angle) to the individual pixels of the photographs. Unfortunately, no starfield calibration photos or position data for reference objects in the photos are available. Nonetheless I tried to estimate the three orientation angles for one of the images (2nd photo from 18:24) using azimuthal positions of roof-edges etc. as calculated from Google Maps aerial pictures and additional constraints such as the vertical orientation of lampposts and the approximately constant scattering angle of the secondary bow. The lens distortions (deviations from the ideal rectilinear projection) were corrected with predefined, lens-specific data in the RAW converter software UFRaw. Though this estimation procedure is only an error-prone stopgap solution (compared to a true calibration with a starfield image) the results are quite convincing. This can be seen best when the rainbow photos are morphed into an equirectangular projection in scattering coordinates (0° in clock angle = rainbow vertex).
I calculated such projections for the 1st and 2nd photo from 18:24, as well as for the last photo from 18:32. The orientation angles I only estimated once (for the 2nd picture from 18:24), whereas I pursued a “dead reckoning” approach using some reference objects to transfer the initial orientation calibration (including its errors) to the other two photos. This allows for a consistency check of the method by evaluating the last picture which shows an ordinary rainbow display. The non-split primary appears, according to the expectation, as an almost straight line with only a slight curvature towards the antisolar point around its vertex.
With the orientation being now somewhat trustable, I took a closer look at the finer details in the triple-split bow. The uppermost branch of the primary is shifted by approximately 1° for clock angles > –60° into Alexander’s dark band, i.e. towards the secondary, when compared to its left foot at around –70° in clock angle. Such a behaviour cannot be explained by the current theory for rainbows generated by flattened drops, since it predicts an inward shift of the primary at its vertex, i.e. away from the secondary, for this elevation of the sun. Elongated rather than flattened drops will yield a shift towards the secondary, but such shapes far from the equilibrium are not stable and will occur only temporarily during drop oscillations. Since these oscillations have periodicities in the range of milliseconds for common raindrop sizes, it is doubtful that a well-defined rainbow, required to be stable over the typical exposure time of a camera (or the human eye), can be generated by oscillating drops with considerable amplitudes. Obviously, such oscillation blurring will be reduced for smaller amplitudes as the oscillations damp out over time, but simultaneously the drop shapes will converge towards their flattened equilibrium states.
Summing all up this means that Kunihiro’s pictures do not only represent the first photographic proof for multi-split bows, but will also give the rainbow theorists something to think about. It might be that we have to take into account additional influences such as electrostatic fields, refractive index variations, or anomalous wind drag.
In the morning of January 24, 2015, I noticed that the sky was covered with low clouds, except for a small gap right above the southeastern horizon, where the sun would rise about 20 minutes later. So I expected a wonderful dawning, but nothing happened. But at 8.10 a. m., I noticed a strange red light coming from the west. When looking out of the southward window, I saw the western and southwestern sky glowing in a dark red colour.
During the following minutes, the red glow slowly extended eastward and became more and more intense. At last it was so intense that even the ground took this colour, giving that morning a quite eerie mood. In the picture taken in northeasterly direction (2) you can see this reflex on the ground, especially on the gravel path and the pedestrian crossing at the lower left. And the picture also shows that towards the east the low clouds still had their normal dark grey colour. In the southeast, no trace of a normal dawning was visible, but higher in the sky there was also this strange red glow from above. (3) This is vice versa to the normal course of a dawning, where the red colour spreads from east to west.
During the next 5 minutes, the light from above became even brighter and turned into a more orange colour (4). At 8.25 a. m., just before sunrise, a bit of sunlight reached the lower surface of the low cloud layer, but it was by far not as intense as the glow coming from above (5).
Author: Peter Krämer, Bochum, Germany