Morning halos

26.8.2009

A nice beginning of the day...a faint upper suncave Parry, 22° halo and tangent arcs...
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Ilus päeva algus...ülemine päikesepoolne Parry kaar, 22°halo ja puutujakaared...


...later around a lunch time the sun climbs higher and the Parry stuff is gone for good.
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...hiljem, lõuna paiku, päike ronib kõrgemale ja Parry kaared on kadunud.

Fogbow at Tallinn-Tartu highway

24.8.2009

This fogbow was simply spectacular ! If looked carefully one might notice the faint and broad secondary bow which is a rare phenomena. Natural fogbows unlike the divergent light fogbows rarely shows the secondary bow. This is due the poor contrast against the background sky.

Circumstances that the observer is facing on a fog-wall and behind the back stays clear sky lit by bright sunlight happens not every day. Usually the contrast is lost when the sky is visible through the fog. A very tall and uniform fog-wall is needed for the secondary supernumerary bow, best places to observe are mountain regions and bridges.

I was able to take only a handful of frames, too bad that I had to go to a meeting that could not be skipped.
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See udukaar (uduvikerkaar) oli lihtsalt hämmastav. Kui hoolikalt vaadata, siis on võimalik näha ka teist udukaart. Loodusliku udukaarega (erinevalt tehisvalgusega tehtud udukaarest) kaasneb haruharva ka teine udukaar. Põhjuseks on peamiselt nigel kontrast taeva taustal.

Udukaar tekib samat moodi nagu vikerkaar. Valguskiired, mis peegelduvad veepiisakeses ühe korra tekitavad esimese kaare. Teise kaare tekitavad valguskiired, mis peegelduvad veepiisakeses kaks korda. Sellega, aga esialgsed sarnasused lõppevad. Vikerkaare puhul võime rääkida valguskiirtest, mis peale vihmapiiska sisenemist, peegeldumist ja väljumist järgib talle kindlaks määratud n.ö optilist geomeetrilist teekonda. Udukaare tekitavad vihmapiisast kordi väiksemad veepiisakesed, mis murravad valguskiiri ulatuslikult. Selline valguskiirte murdumine annab udukaarele peaasjalikult valge värvuse koos ähmase punasega väliskaarel ja ähmase sinisega sisekaarel. Erinevalt vikerkaarest on udukaare värvid laialivalgunud, sest iga värvi spekter kaarel on väga lai ning värvid kattuvad omavahel.

Teise udukaare vaatlemiseks oleks ideaalne kõrge ning ühtlane udusein, kusjuures vaatleja selja taha peab jääma selge taevas ning päikeseketas. Tihtipeale läheb kontrast kaotsi, kui udu tagant paistab ka taevas. Parimad vaatluskohad oleksid sillad, künkad ja orunõlvad.



Btw: this is another image which made it's way to Les Cowley's magnificent OPOD page.
Edit: Taken Tallinn-Tarty highway, near Vaida, about 500m away from the pedestrian bridge.
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PS: see on juba minu teine foto, mis on avaldatud Les Cowley imelises OPOD veebilehel.
Ja veel: Pildistatud Tallinn-Tartu maanteel Vaida lähistel, umbes 500m jalakäijate sillast Tallinna poole.

22 tangent arcs

23.8.2009

A bright halo. My old Canon dslr simply can't present the brightness-contrast rate and colours properly. I guess modern dslr's can do this job way better.

Upper sunvex Parry arc

15.8.2009

The upper V-shaped arc is known as sunvex Parry arc which is very rare sight in upper cloud layers.

Moon halo

11.8.2009

Stack from 4 very long exposure time frames.

Fogbow

09.8.2009

I woke up early to get to port Dirhami to take a boat to Osmusaare. Morning struck me with nice thick fog. Unfortunately I had to get there on time but fog slowed me down - every now and then my speed was only 40km/h. Besides that I took way too many moments to photograph fogbows which got better and better but then I was completely out of time...

CZA

31.7.2009

A single CZA across the sky. The image really do not justice the actual brightness and size of that arc...still I have seen better ones, like this back in 2006 October.

Another Parry suncave

30.7.2009

Faint Parry suncave

29.7.2009

Here a faint upper suncave Parry arc. 12 image stack. Single frame reveals only tangent arcs, no trace of Parry. Interestingly this display is formed only by the column shaped ice crystals, no plate crystals here.


Same stack as the above image but without the Usm filter.

Parhelias at parking lot.
About 2 hours later column arcs are vanished and replaced by the plate crystals.

Update for an old post

I have got some free time in my hands so I decided to work on some old photographs. This stack is made of 8 frames and should belong in this entry.

11.5.2009


After some heavy unsharp masking in Photoshop parhelias and tangent arcs are revealed. Some would call this hair-splitting and I agree on this.

23 parhelia vs. tangent arcs

24.7.2009

Here checking a faint solitary 23 parhelia stack against the 22° tangent arcs. For a moment it seemed that it was a poorly developed tangent arc and almost not worth the trouble to stack. Afterwards (something like half moth later) a quick comparison gives near 99.9% proof that we are dealing here with 23 parhelia and the case for tangent arcs is not valid.

NLC's from July

28.7.2009