Monday, December 25, 2006
MoP clouds are seen a number of times each winter in Finland, but displays as bright as this one are fairly rare.
Usually the MoP clouds are related to stratospheric temperature colder than -80°C.
Tuesday, November 14, 2006
More Pictures: 1 2 3 4 5 6 7
Friday, November 10, 2006
Tuesday, October 31, 2006
The 00 UTC 29 October sounding of Denver doesn't show unusually strong winds at high altitude, at 40 to 50 kts from the NW. In fact the entire troposphere seems rather dry on that particular sounding for lenticular clouds to occur.
I do not think this was caused by a missile launch either, considering the lenticular shape of the clouds.
I am wondering if these could be stratospheric clouds, or just some quite unusual appearance of lenticular mountain wave clouds. I received another report from someone else in Colorado who also took images, and am waiting for her approval to post them here as well.
Thursday, October 26, 2006
More pictures: 1 2 3 4
Tuesday, October 17, 2006
Sunday, October 15, 2006
Even though these coronas are smaller than before, they still are large as compared to pollen coronas. Unfortunately I have no photos for comparison.
In the composite image are two coronas photographed with same lens (not to scale with upper single image, which has been taken with zoom lens). The microphotograph of the bacterial film is from the smaller corona on the left.
The light source was a 50 W halogen spotlight that I made even more concentrated by placing the lamp in a cardboard box, into which a small hole was made for light to come through. When taking photos, the room was otherwise darkened.
Saturday, October 14, 2006
A camera team made a film [40MB, for WINDVD, in German!] about search of the Spectre and the edge Ghost but unfortunately the quality of digital version is not very good.
Spooky greetings from the ghost heaven!!!
Friday, October 13, 2006
On the evening of October 7 the weather was windy and rainy. I went out to take photos of rainbow using very powerfull light source. The shaft of light is narrow, but it illuminates buildings that are more than one kilometer away. The distance from the photographing spot to light source was about 150 meters. On October 10 I took photos of fogbow. It was amazingly bright and seemed to show up better closer to the light source.
Friday, October 06, 2006
Location: Papatoetoe, Auckland, New Zealand.
Wednesday, October 04, 2006
Saturday, September 30, 2006
Also two photos of the optical phenomena caused by this alga are displayed in the composite. On the left is a fisheye view with Quetelet rings. The glow around the camera shadow is fogbow. Notice the brightening towards nadir in fogbow, indicating possibly non-spherical particles. The photo on right is taken further away from the cultivation tub, showing spectral colored glory rings. Attached to the outmost glory ring is faint, white fogbow.
All said here about the biology of C. rosanoffii was known long time ago. The alga was described in 1880 by Russian botanist Woronin, who encountered it while visiting Finland. One aspect of the studies carried since has been the golden glow that well developed C. rosanoffii surface film displays, as shown beside and here. But I have not yet met in the literature any mention of the spectral colors, which strikes me as a small wonder. However, there is still plenty of reading to be done, so something may come up.
Wednesday, September 27, 2006
Only a segment of the corona could be seen in the small bucket. This is shown in the upper left image. Unlike the peculiar corona described by Piikki, this one has true blue aureole starting right from the reflection image of the lamp. Outside the blue some green and perhaps red maybe distinguished – visually these colors were clear. Upper right image is microphotograph of the film. It consisted of bacteria.
Day after taking the upper photographs the phenomenon in the bucket changed. Now there was similar corona as what Piikki photographed, only less bright. This is shown in lower left. There was no aureole, but instead a dark area surrounded the light source. This also was consistent with Piikki’s observation. Microphotograph of the film on this stage is shown on the lower right.
The most conspicuous difference in the bacterial level between the two stages is the crowding – there are more bacteria in the latter stage. Is this somehow related to the changes in the phenomena? Perhaps Minnaert can give an answer. In the chapter about coronas seen in windows, he describes how these coronas have an aureole replaced by dark area. He speculates the dark area forms because in the two dimensional plane of the window surface the droplets can be evenly spaced – a situation which can not happen when particles are freely floating in the air.
Now, if one looks at the lower right microphotograph, one can imagine that these bacteria indeed are spaced more evenly as compared to the upper photo. In the Piikki’s microphotograph, which looks like a maze, the bacterial film might consist solely on the long strands that are seen in small numbers also in my lower right photo. When packed next to each other, these kind of strands would possibly be very evenly spaced, thus perhaps contributing to the stronger corona. Piikki’s photograph is, however, too much out of focus to be sure of this interpretation.
The bacteria species could be Nevskia ramosa, which is well known neustonic (water surface inhabiting) bacteria. Genomic fingerprinting would be needed for confirmation. For the last note it should be said that the inverted colors between the two microphotographs are due to differences in focus. The upper image is a bit out of focus and thus the bacteria shows as dark spots.
Tuesday, September 26, 2006
When I programmed a Mie simulation algorithm late last year and plotted a polarized fogbow on my screen, I was surprised that the polarized bow looked as it did, with the typical Brewster's angle 'gap' in the main bow for parallel polarization. How excited I was to see that the actual fogbow indeed looked like the simulation! I had never seen it before in nature.
I am sure this has been done before by someone else, but I thought I would post the images anyway.
I covered up one of the car's headlamps as to not have a double bow. I positioned myself about 50 meters in front of the truck, which I had parked on a slight inclination so the bow would be better visible against a featureless sky and be more complete. The fisheye lens was equipped with a polarizer at the place in the lens where the rays go parallel.
The simulation I made earlier, for a 10 micrometer radius droplet. It looks sharper because I assumed a point light source, assumed a monodisperse droplet distribution, and it was not divergent light. It is not a perfect match either considering the placement of the supernumeraries: probably the droplets in the actual display were a bit smaller. Because of the divergent light source, and because I don't know the distance to the truck accurately, I doubt I will ever be able to accurately tell the actual droplet radii in the display.
The polarized glory was also obvious, but my shadow was blocking most of the part that was most polarized. I am including the unpolarized glory here.
The close-ups of the polarized and unpolarized fogbow were made with a 24mm/2.8 lens. The camera was a Canon 300d (modified version - i.e. with IR filter removed). I did not need to adjust the brightness and contrast much to get the results as displayed here. The fogbow had good contrast by itself.
About 10 days later I documented a natural fogbow in sunlight from the laboratory, through a polarizer. I photographed that with film; I have not processed those photos yet.
Tuesday, September 19, 2006
At 19.18 CET (Daylight saving) the sun disappeared behind a 250 km distant thunder cloud over the Black Forest, Schwarzwald, in South Eastern Germany. Then the sun would have been ~2° above the astronomical horizon. The sea level horizon was 197 km distant and dipped 1.4°.
At around 20.00 sheet lightning was noticed on the horizon.
At 20.15 a 30° long crepuscular ray was formed by the thundercloud. At that time, nearly an hour after sunset, the sun was 8° below the astronomical horizon. The ray was faint but clearly seen over the remaining twilight colours. The image was made with a 150mm lens and a 4s exposure.
Wednesday, September 13, 2006
Monday, September 11, 2006
Jari Piikki also found a new optical phenomenon. He took (like Marko) some samples from ponds and cultivated them. In one of them Chromulina disappeared and some other alga appeared. There could be seen a very colourful ring with two zones of spectral colours around the reflection from the surface of the Sun or an artificial light. The ring was oval and became smaller, when the light was brought closer to the water surface. Its diameter in sunlight was about 30 degrees and the inside was dark, so it was not an aureole. also visible when the light shone through the alga from below. Many photographs of the surface were taken with a microscope to show its structure. You can see it in some photos. The alga constantly changes constantly and now shows small colourful blotches.
[Text: Jari Piikki]
Saturday, September 09, 2006
The upper pair of photographs shows elliptical corona and the alga that caused it. Pine pollen gives the scale. This corona-type display has no other phenomena.
The lower photo shows another type of display, which exhibits Quetelet rings, brightenings around sun's reflection image, glory and fogbow. In this case there is also unidentified diffuse feature marked with arrows. In addition, fogbow and glory have spot-like brightening towards nadir. Two B&W photos of the algae causing this type of display are shown. In the lower photo the algae are possibly turned 90° in comparison to upper, showing elliptical shape. This species might be Chromulina rosanoffii. It's about 5-10 µm in size (not to scale with upper color photo) and well transparent to make glory.
These phenomena turned out to be common, at least this summer. They were most abundant on rocky Finnish archipelago islands, which harbour endless number of small rock pools.
Friday, September 08, 2006
A divergent light source can actually produce a multiplicity of rainbows, not only of angle 42° but at larger angles also. The net result is that the bows overlap and a discrete coloured arc is no longer visible. Another negative factor is that the rainbow cannot develop a high intensity like those sourced by the sun because only a narrow range of rays fall on the "rainbow cone" having its tip at the observer's eye. To see a divergent light bow it is necessary to be far away from the light source so that its rays are as parallel as possible and develop a bow of sufficient contrast.
In the photograph the divergent light bow is wider horizontally than vertically. This is because the two car headlamps each form bows and so produce an apparent broadening.
Sunday, August 13, 2006
Saturday, July 08, 2006
From meteorological experience, a dying cumulonimbus can only produce ice when it collapses from the top and in the lower levels the temperature is low enough that the ice does not melt. That was the case here, the cloud collapsed and decayed fully into graupel. There was definitely no rain, which I had also not experienced previously with a ice pellet showers.
I do not want to commit myself whether there can be an ice pellet bow. However, the ice grains may occasionally be covered with a water layer, giving a smooth outer surface. Of course, the refraction in the ice-water interface must also be considered. If that interface was uneven it could explain some of the bow width.
On 11th of January 2006 Christian Fenn reported crystal-clear ice balls (photo 1, 2), in sleet falling at an air temperature of -4°C. He searched for an ice bow formed from the headlights of his car. In this picture the possible ice bow is compared to a (terrestrial) rainbow. There are also images by Christan Fenn of the ice balls.
Friday, June 23, 2006
The white dots are wind dispersing seeds, probably of some willow species. They are more abundant in the lower image, which was taken in town. The upper image was shot in the midst of pine heath, with correspondingly less white fluffs in the air.
On 13. June 2006 in Eastern Finland. Larger sized versions are here.
Thursday, June 22, 2006
Even though the picnic basket contained several tasty titbits the sky was even more tempting with its unusual mirages. Ships passing Heligoland and Düne at a distance of 10 km or more appeared somehow "stretched". They looked longer than they really were.
Thorsten and Bärbel are still wondering how this effect come about. The sun was shining the whole day and because there was almost no wind, a warm air layer probably lay above the water surface. They suggest that when a ship is on a course of 45° (for example) towards or away from the observer, the bow of the ship is closer/further to the observer than the stern. This, combined with the warm air layer, may cause the unusual extension/or sometimes shortening of the ship.
The two images are 15s apart. More mirage images here.
[Text: Thorsten Falke & Bärbel Wichmann]
Tuesday, June 20, 2006
Thursday, June 15, 2006
Tuesday, June 13, 2006
I saw this extremely splendid cedar pollen corona on May 19, 2005 at Hachioji, Tokyo. Last year, the amount of cedar pollen was so large that we could observe some beautiful coronae (but it was a nightmare for people caught by hay fever).
Cypress pollen is another source of pollen coronae in Japan. However, the season of Japanese cypress pollen is almost same as that of our cedar pollen so that it is hard to distinguish its contribution from the cedar pollen's contribution. (The amount of cypress pollen is less than cedar pollen.)
Saturday, June 03, 2006
It might be the first report of a pollen corona in Japan, other than by ceder (or cypress) pollen.
Tuesday, May 30, 2006
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?
[Report: Reinhard Nitze]
Wednesday, May 24, 2006
The phenomena were visible on many days between May 2-11 and were possibly produced by smoke carried from Eastern Europe.
In the above corona image taken on 11th May a small segment of another photo has been added to show the size of 22° halo for comparison.
The sunset was photographed on 4th May.
Large coronae can be seen during very warm weather periods when the sky is usually hazy. This was the first large corona seen in Finland since the Bishop’s rings of 1991-1992. Smaller coronae (radius of about 5°) with a blue disk and brown ring have sometimes been observed.
[Text & Report: Jari Piikki, Juva Finland]
Monday, May 22, 2006
Saturday, May 20, 2006
Friday, May 19, 2006
That day Reinhard Nitze took very unusual pictures of the alder coronae. On the one hand the coronae were intense but appeared together with another phenomena, e.g. with iridescence clouds or cloud rays. Sometimes, however, Reinhard saw them "undecorated".
Sunday, May 14, 2006
Cyan saturation was increased in the photo to make the inner blue disk better visible. Otherwise the photo is as scanned from the slide. See here for some more material. The degree grid is made with HaloSim by Les Cowley and Michael Schroeder.