The ever growing number of webcams is worth to be checked for both common and rare atmospheric optics phenomena, e.g., like in the case of these twinned rainbow, rainbow at high and low sun (1–2–3–4), red rainbows (1–2–3–4) or moonbows (1–2–3–4).
The Swiss webcam located in Cully at the North shore of Lake Geneva (Lac Leman) has shown a most unusual pair of images within 10 minutes on May 25th, 2016. Starting from the last image (see top right) taken at 20.40 Central European Daylight Saving Time we see fragments of a normal primary rainbow before sunset, which happened at 21.08 CE-DST. From its beginnings on the lake’s surface it is immediately slanted toward the antisolar azimuth in the East.
However, the image taken 10 minutes earlier (see top left), at 20.30 CE-DST, shows not just a weaker bow, but also, that it starts at the lake’s surface slanted toward the West, i.e. away from the antisolar azimuth!
This strange sight is an isolated reflection rainbow, which is also centered on the antisolar point, but, at the solar elevation of 4.9°, somewhat larger than a semicircle, thus explaining the odd slant at its foot. The missing of a normal rainbow (except of, may be, a slight trace) in this image can be explained by a very patchy type of rainfall or shadowing of the corresponding regions. Additionally, the images show hints of a reflected rainbow and a reflected reflection rainbow, respectively, projected on to the lake’s surface.
Authors: Elmar Schmidt and Claudia Hinz
What kind of rainbow is that? This is no fake this is real! Ok…it’s a little trick with an open window and the right angle to the sun.
The rainbow are produced with a water spray bottle. The right bow is the “real one” and the left bow is the reflected one.
The reflected surface in this example is the window in vertical direction, so the bows looks like a “x”. (2)
Place : Pforzheim, Germany
Time : 18 May 2011
Digital Camera : Panasonic DMC-FZ50
Exposure : 1/200 sec , f/3.6 , ISO 100
Author: Michael Großmann, Kämpfelbach, Germany
When I wanted to go to work in the morning of February 24, 2010, I noticed a colourful rainbow forming during a short local rainshower. At first the weather had been fine that morning, and ist was almost calm, but then some rain clouds came up from the southwest and started to cover the sky. The sun was shining brightly at that hour (about one hour after sunrise) and made the rainbow shine in especially bright colours. So I hurried to get my camera and started to make some photographs. While I was taking pictures, I was astonished to see a third bow forming, which intersected with the secondary bow. At the first moment I thought that there was something wrong with my eyes, but I could see it also when I looked at the pictures already taken on the camera display.
I was excited, although I could not make head or tail of it – I had never seen such a thing before. Later, as I searched the world wide web for an explanation, I learned that the phenomenon must have been caused by a reflection. But the reason for the phenomenon was still not clear, as there was nothing between me and the rainbow that could have reflected any light.
Only much later I could solve the mystery: The reflection was caused by the Hallwilersee (Lake Hallwil), which was at about 3 kms behind the position where I had taken the pictures that day. The lake cannot be seen from the place where I saw the rainbow, as there is a hill between the lake and that place. So I did not take this possibility into consideration at first. The position and elevation of the sun, my position towards the lake and the distance from the lake fitted perfectly that morning to form this rare phenomenon for a few moments.
Author: Matthias Frei, Dürrenäsch, Canton Aargau, Switzerland
Mark Worme observed this rainbow today at around 3.15 pm Atlantic Standard Time in central Barbados facing east. At first he only noticed the double rainbow, but then he realized the lower one was split.
During a heavy rainshower, a twinning of the upper part of a rainbow can sometimes be observed, which often lasts from a few seconds up to several minutes. As for a long time there were only few observations of this phenomenon available, only speculations could be made about its origin. Only in the past few years, this twinning could be registered more often by continuous observations, and due to some detailed descriptions, new theories could be advanced. As in all observations both bows are of equal brightness, light refraction on ice particles can be ruled out. Most probably is that raindrops of a non-spherical shape produce one of these bows or even both of them. Due to surface-tension, small rain droplets hardly change their shape when falling, but large drops can be flattened by the air resistance. The more flattened they become, the smaller is their refractive index. So the sunlight has to fall upon water drops of different size at the same time to make the twinning appear. As this twinning was up to now observed under big shower or thunder clouds which formed in hot air, it can be supposed that the small, not flattened raindrops evaporate at a short distance below the cloud basis. This would explain why the twinning can only be seen for a short time and exclusively in the upper part of the rainbow. It should be important to determine the radius of the rainbow when the twinning is observed, and to record the weather situation at the time the twinning appears as exactly as possible.
I and my wife Eliisa Piikki got a hint about a light phenomenon on a lake nearby. Eliisa took some photos and there was a dewbow and a reflected light dewbow in those photos. They were formed on the waterdroplets that were settled down on the Chrysomyxa ledi needle rust (Small-spored spruce-Labrador-tea rust).
That rust can’t be seen in Finland every year, but this year it is very common especially in the Eastern and in the Northern Finland. Because of the rust the young needles of some spruces are brown.
Author: Jari Piiki, Finland
For the moment, the precise location of sun ray reflection is not yet analysed… To see her other rainbow photos for same evening, look at here.
Update (11th Aug 2009):
There is another gallery existing of the reflection rainbow, in same date and location, taken by Sami Luoma-Pukkila.
Posted by Timo Kuhmonen
On 22nd August 2006 between 20.35-20.50 hrs, while cruising on the Isfjord near Spitsbergen, Nicola Boll watched these wonderful reflected rainbows. The lower bow is an ordinary primary bow. Intersecting it and curving upwards above it is a ‘reflection bow‘. The bow is formed by sunlight reflected off the smooth waters of the fjord. The upward going reflected rays are, in effect, from a ‘virtual sun’ the same distance below the horizon as the real sun was above it. Since rainbows are always centred opposite the light source, the centre of the reflected bow is up in the sky and the bow correspondingly high. In the picture enhanced by unsharp masking a reflection bow is also visible curving upwards above and to the right of the secondary rainbow.
Though these photos are old but when it come to making rainbows with garden hose sprays this is an unusual one. I knew reflected light rainbow required a smooth body of water to form and at the time we still had an above ground swimming pool and its surface was glass smooth and I got the garden hose turned on and saw not only primary and secondary but in between those was a reflected light primary! I continued to experiment and I got some photos with the old Kodak DC215 which has been retired since I use my Nikon D-100. I don””t know if anyone has ever tried a homemade reflected light rainbow with a garden hose and a smooth surfaced swimming pool but mine may not have been the first or the last.
Author: Michael Ellestad
This image was taken during a violent storm that produced golf-ball-sizedhail as it passed over. The interesting thing about this reflected-lightbow is that there was no large body of water to produce the reflection. The source of this reflection was most probably a wet highway, the Trans-Canada Highway, west of Calgary. Since this part of the highway wason a hill, the reflected-light bow appears relatively high compared to theexpected position from a horizontal reflection surface.
Author: Alan Clark
Uwe Mueller from Bremerhaven photographed this reflected light rainbow at the 06/10/04. The reflector surface is with large probability the transatlantic harbor at the external Weser, which was at the time of the admission behind the observer. This rainbow was visibly of 15.45 UT- 15,54 UT. At the beginning of the sifting the reflected light rainbow was good visible. It became then fast weaker.