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Saturday, 27 October 2007
Sunday, 21 October 2007
Ellipszis-alakú halo - Elliptical Halo
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While I was taking photos of the iridescent Ac clouds, I noticed this rare elliptical halo that lasted less than two minutes. Further description on haloreports blog.
A képek teljes méretben / Photos in full size: 1, 2, 3, 4
Módosítva, hogy jobban látsszon a jelenség / Enhanced images: 1, 2, 3, 4
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These lenticular (Ac len) clouds were visible at the same time in the sky.
Friday, 19 October 2007
Tuesday, 16 October 2007
Sunday, 14 October 2007
Kausztika - Caustics
Wednesday, 10 October 2007
"Tollkorona" #2 - "Feather Corona" #2
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The coronae presented here are on an owl's feather. The darker photos were taken by the light of a torch. First I thought that the chequered pattern had been caused by multiple internal reflection within the torch, but then I realised that the same effect could be observed by sunlight and it is actually interference. Today I found out that this pattern can be seen on yesterday's dove-feather, as well.
Tuesday, 9 October 2007
"Tollkorona" - "Feather Corona"
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A koszorút, más néven koronát, szórás (diffrakció) okozza, és gyakran figyelhető meg a Nap vagy a Hold körül, ha az előtte levő felhőt egyenlő nagyságú apró vízcseppek, esetleg jégkristályok alkotják. Viszont koszorút más is okozhat. Tavasszal és nyáron azonos nagyságú és alakú virágporok jelenléte a levegőben pollenkoszorút (-koronát) hozhat létre. Ennek alakja a pollen fajtájától függően változik. Ha pedig a nap sugarai elé madártollat tartunk, a toll szabályos szerkezete szintén sajátos "koszorú"-jelenséget mutathat. Minden egyes madártoll apró ágacskákból, és az ágacskákon elhelyezkedő még apróbb egymásba kapaszkodó horgokból áll, melyek tökéletes illeszkedése teszi lehetővé a madár számára a repülést. Ez a szabályos felépítés az, ami miatt létrejöhet a szabályos koszorú, melyet (mivel egy madártoll felülete igen kicsi) legjobban akkor láthatunk, ha a fényt kisebb résen engedjük keresztül. Használhatjuk például egy fa leveleinek félárnyékát, vagy megvárhatjuk, míg a napot félig kitakarja egy felhő. A képeken egy balkáni gerle (Streptopelia decaocto) tolla látható. Az első fotón a toll teljes napfényben van, így a koszorú sávozása nem vehető ki olyan jól. A második két képen viszont többször is szépen megjelennek a színek, mivel a tollat csupán a fa ágai között áttörő napfény éri.
The corona is a diffraction phenomenon, which is well-observable around the Sun or Moon if the clouds in front of them contain droplets (or ice crystals) of the same size. But coronae can be caused by other materials, too. In spring and summertime pollen grains of equal shape and size present in the air can cause the formation of a pollen corona. Its shape depends on the type of the pollen. If, however, we cover the Sun with a bird's feather, we can see how its regular structure creates a special "corona"-effect, too. Birds' feathers are built up of barbs, barbules and tiny hooks interlocking on them. If they were not so perfectly locked together, birds would not be able to fly. This repetitive structure of barbules and hooks of the same size creates the corona pattern. It is best visible - as the surface of a feather is rather small - if we let the Sun's rays through a somewhat smaller opening. It might be a gap in a tree's leaves, or by waiting till the Sun is half hidden by a cloud. In the photo, the feather of a Collared Dove (Streptopelia decaocto) can be seen. The first picture shows the feather in direct sunlight, so the bands of the corona are not too sharp. The second two photos, on the other hand, show the feather in sunlight partly covered by the branches of a tree, thus the bright colourbands become apparent.
Sunday, 7 October 2007
Macskavárvány - Spectral Cat :)
Saturday, 6 October 2007
Friday, 5 October 2007
Pókfonal - Silk Thread
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In this photo, the delicate structure of a spider's silk thread can be seen. The size of these tiny sticky droplets can be estimated by looking at the little aphid caught in the web. Its wings are about 3 mm. The picture has been slightly enhanced in order to show how the light rays are refracted, producing the spectral colours.
Thursday, 4 October 2007
Reggeli 22° halo - Morning 22° Halo (Vecsés, Hungary)
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Extremely faint 22° halo and parhelion on the contrails.
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A mai nap fénypontja: Alex 120°-os melléknapja!
Today's highlight: 120° parhelion caught by Alex!
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