Blog Archives

Double dewbow

On June 25, 2010, Rüdiger Manig observed a double dew bow on unevenly spread morning dew on a leaf in Neuhaus am Rennweg (Thuringia, Germany).

Especially when he slightly defocussed his camera, the bow could be distinguished better.(123)

Actually, the distance between the two bows was less than 10°, the angle which one could expect in a double dew bow. Maybe, however, that the angle of refraction was significantly reduced by the deformation of the droplets on the leaf.

3rd and 4th order rainbows

Last evening (11 June 2011) thunderstorms approached my home town Schiffdorf near Bremerhaven in Northern Germany. I went to a field road by car to take some photos of the storm clouds. Just after I had arrived (about 18:00 UTC), heavy rain started which lasted for nearly 20 minutes. To my disappointment, the rain covered the gust front and most of the interesting features of the storm. So I waited and hoped that the sun would come out soon and produce some nice rainbows. When it did I realized that the dark clouds covered the sky to the right of the Sun – just the situation Michael Großmann had had when he took the the first image of a 3rd order rainbow only four weeks ago. I decided to try this out as well. Instead of one image I took sequences of five to stack them and, thus, increase the signal-to-noise ratio. I hoped this would increase my chances to detect the 3rd order bow. I took the images from my car through the open window to protect my camera (Canon 40D) from the rain. Visually, I did not see a 3rd order rainbow. However, in my back, the 1st and 2nd order bow developed nicely.

Back home I converted the raw images to 16-bit-Tiff and stacked them in Photoshop. Adjusting saturation already showed the 3rd order bow in the image sequences taken between 18:17 and 18:22 UTC (first image).  Applying unsharp masking revealed something unexpected in one of the stacked images (from 18:19 UTC): There seemed to be another rainbow close to the 3rd order bow, but, with reversed colors (second image). I checked Les Cowley’s website and realized that my image likely showed the 4th order rainbow!

After some more sophisticated processing including denoising (Neat Image), unsharp masking and increasing saturation, the 3rd and 4th order rainbows both were clearly visible. Finally, I created a composite using masks to retain the natural look of the foreground while still showing the 3rd and 4th order rainbows (third image).

Author:  Michael Theusner, Bremerhaven, Germany

Full circle rainbow

Partly because of my embarrassment to capture any pictures of rainbow this year, I dug up my old idea about how to create a circular rainbow and went to a local shop.

After few hours with some assistance, a bent-looking sprinklers frame was completed (1). The first test on 2 June 2011 was somewhat unsuccessful because the sun was too high and I could not find a right angle to see the whole rainbow circle.

For a few days, rain storm after rain storm poured down over Bangkok, with no sunlight in the morning. On 5 June 2011, a heavy rain hit Bangkok again before sunrise, but the sun appeared around 7:30 AM. Many rainbow shots were taken (2) and the photos were stitched together by “AutoStitch” on a PC.

Place : Bangkok, Thailand
Time : Sunday 6 June 2011, approx. 7:44 AM
Rainbow Equipments : A row of sprinklers placed approximately 4 meters above the street
Digital Camera : Ricoh GX200 + 19 mm. wide angle lens
Exposure : 1/200 sec , f/4.1 , ISO 64, Daylight setting
Photo Processing : 4 pictures, stitched together by ‘AutoStitch’ on a PC, no image enhancement

Author: Pitan Singhasaneh, Bangkok, Thailand

Natural tertiary rainbow 3rd order

On May 15, 2011, a rain area moved from north to south. When it started to rain at my position, I immediately rushed to my observing site which is reachable within 2 minutes for me.

Once there, I saw beautiful specimen of the primary and secondary rainbow. During my observation,  the rain intensified, and now I knew hat I had to look for!

On the left side of the sun there was a relatively dark cloud bank providing ideal conditions for a possible sighting of the 3rd order rainbow.

In fact, I had the idea of seeing a very faint arc at the expected position of about 40° away from the sun. It is really exaggerated to say that I saw it, but there seemed to be something.

I went into the shadow of a tree in order not to be blinded by the sun.

Now I did not take any care to protect the camera from the rain, I just had a little box with me to put the camera into. The arc could not be seen for more than 30 seconds, but I´m sure there was something at that position.

As under those lighting conditions a correct exposure is hard to get, I took my photographs in RAW mode. All the “little helpers” of the camera had to be set off.

To my disappointment, I did not find anything at the expected position when examining my pictures on the PC screen. But when putting an unsharp mask over the pictures, I saw it immediately. A bow! You can see that the outer part of the bow is slightly red and the inner part is light green.

Here is an animation showing the original image and three different settings: Unsharp mask, intensified colours and inverted.

If you need more information about the measurements of this tertiary rainbow, take a look at this pdf-file written by Dr.Alexander Haußmann. Thank you very much for your calculation!

Author: Michael Großmann, Kämpfelbach, Germany

Rainbows and supernumeraries

During last weekend (Sunday 4th May -08) at city of Espoo, I observed seasons first rainbow. Local thunderstorm came along with rainshowers produring primary and secondary bows. I visually saw 3 primary supernumeraries.

In the heavily enhanced image (USM) of primary bow there is small hint of 4th supernumerary visible. Outside of seconday bow there is larger arc (dark pink color), assuming it indicates supernumerary also… The droplet sizes may been quite even, due to easily visible interference bows.

Posted by Timo Kuhmonen

Heiligenschein and dewbow in moon light

Well, I wanted to observe moon halos that evening, but the sky was totally clear without any cirrus clouds.

I noticed that some blades of the plants on a field were rather wet. I walked some steps into the field and immediately noticed a clear brightening around the shadow of my head. I did a few steps to the left and to the right and could see a very faint dew bow. So I took some photographs at different exposure times and ISOs. The best photographs (1 2) I achieved using stop 4, an 18-mm-lens and at a time of exposure of 45 seconds at ISO 400.

Author: Michael Großmann, Kämpfelbach, Germany

Multiple rainbows

Jan. 12, 2008
Riding home on the bus this afternoon, I noticed the rainbow off to the East. The sun was low in the west and was not far from setting, so the clouds were beginning to take on a golden hue. The rainbow looked like it was repeated numerous times and fading off in the distance. I got off at the next stop and pulled out my new pocket-sized digicam and snapped a couple of pics. I checked out Les Cowley’s Atmopsheric optics page and it seems that the closest thing I could find were supernumerary bows, but these seemed to be more spaced out than the examples on his website. So is that what these are? I have included two pictures (1 2) and two contrast enhanced b&w versions of the pictures to better show the details (1 2).
Picture details: Canon SD1000, ISO 200, 1/160 sec, f4.9

Author: Darryl Luscombe, Vancouver, British Columbia, Canada

Reflection of camera flash-light in a glass of white wine

refexion

A good friend of mine is celebrating his birthday early in September. Recently, we celebrated his 53rd birthday on a Saturday evening in an Indonesian restaurant in the centuries-old city of the town of Utrecht, in the central part of The Netherland. This (school)friend was one of the three guys who initiated a group of youngsters at the end of the sixties and the start of the seventies (of the 20th century), interested in astronomy, weather and … optical phenomena. The initiative grew out to the nowadays Dutch “Vereniging voor Weerkunde en Klimatologie” and the “Halonet” optical observers group.
During the superb birthday dinner, one of the people of the restaurant made a picture with a digital camera-with-flash-light, while we were toasting for the health and wealth of the hero of the feast.

Absolutely by chance, it happened, the flash-light of the camera reflected in the glass of white wine I raised for the toast (the yellow “light” clearly visible in the picture).

It seems, some people are just born for optics …

Author: Frank Nieuwenhuys

Reflexion on water surface

Brigitte Rauch and her husband spend every free minute on their motor-boat on the waters around their home island Helgoland, whichis only about one square km large and situated in the open North Sea. If possible, they do not miss any sunset and always have their camera ready to hand. This photograph of reflections on the water surface was taken on July 17, 2006, just after sunset. The colour of the sky and the clouds are reflected from the water surface, which was relatively smooth that evening. The patterns are caused by small waves. This richly coloured interplay of sky, clouds and waves can be seen only on a few days of the year.

More pictures: 1 2 3 4

Spider web reflections

In Germany October 2005 was very dry, calm and warm with no frosts. The weather gave rise to a large number of spiders and of course their webs. Towards the end of the month, Reinhard Nitze’s attention was drawn to an unusual light phenomenon on a ploughed field. The sun produced a silvery reflection like the glitter path seen on waves when the sun is low. He had seen the effect earlier on scythed grain and grass fields but never so conspicuous. The effects were produced by sunlight reflecting off threads of spider silk that happened to be perpendicular to the sun – eye line in the numerous webs in the fields (more images 1,2,3).

The effect is seen also in the lower left image where the web reflections in trees make concentric rings.

Bare and wet twigs produce similar effects as do support wires in vineyards. Perhaps observers have seen other reflection effects like these?

[Text: Reinhard Nitze]