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LaurV 2020-10-08 03:51

Solar Halo
 
Nice [URL="https://en.wikipedia.org/wiki/Halo_(optical_phenomenon)"]solar halo[/URL] yesterday in Chiang Mai. It looked exactly like on wiki, you could almost see two suns on the sky. I didn't know about this phenomenon, it is new for me. Unfortunately, I don't have photos, but some local people made movies which are now circulating around, I will ask if I can post any.

Dr Sardonicus 2020-10-08 13:51

See also [url=http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/halo.rxml?hret=/guides/mtr/opt/ice/sd.rxml]22 Degree Halo[/url] and [url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/sd.rxml]Sundogs[/url].

I've seen sundogs a couple of times; 22 degree halos more often.

Sundogs are said by some to be a sign of good luck. But they (or a halo around the sun or moon) indicate the presence of cirrus clouds, which are often a natural indication of an approaching storm.

There is completely different effect which I've only seen from the window of a plane flying above clouds. It is called the brocken specter. It is a shadow which often has a colored halo (glory) around the end opposite the sun. If you're on a mountain with clouds below, with the sun low in the sky, you might see your own shadow with a halo around your head.

bsquared 2020-10-08 14:32

4 Attachment(s)
I took these pictures in January 2019 on a windy -33F (-36C) degree day, on my way to work in the morning. I remember barely being able to hold the camera steady after just 30 seconds or so in the -70 degree wind chill.

You can clearly see the sundogs (nearly as bright as the sun!), 22[SUP]o[/SUP] halo, 46[SUP]o[/SUP] halo, and upper tangent arc. Possibly portions of the parhelic circle extending horizontally from the sun. Or maybe that's some kind of lens flare. I wish my photography could do it justice.

xilman 2020-10-08 15:32

[QUOTE=bsquared;559257]I took these pictures in January 2019 on a windy -33F (-36C) degree day, on my way to work in the morning. I remember barely being able to hold the camera steady after just 30 seconds or so in the -70 degree wind chill.

You can clearly see the sundogs (nearly as bright as the sun!), 22[SUP]o[/SUP] halo, 46[SUP]o[/SUP] halo, and upper tangent arc. Possibly portions of the parhelic circle extending horizontally from the sun. Or maybe that's some kind of lens flare. I wish my photography could do it justice.[/QUOTE]Seen all of those, but with nowhere near the clarity of your images. Well done!

Once managed a Brocken spectre from the Swiss Alps. Very common from aircraft IME.

Also seen a few lunar rainbows, though without any colour --- which is possible with long exposures but not, AFAIK, with the naked eye.

Also once managed a Jovian shadow of my head with the naked eye under [i]very[/i] special circumstances.

bsquared 2020-10-08 17:31

[QUOTE=xilman;559261]

Also once managed a Jovian shadow of my head with the naked eye under [i]very[/i] special circumstances.[/QUOTE]

I would like to know more about this.

xilman 2020-10-08 19:04

[QUOTE=bsquared;559271]I would like to know more about this.[/QUOTE]Back when I was a grad student, about 1980 or so, and living in Oxford we had several cm of snowfall. Subsequent days had a maximum temperature just barely above freezing with most of the time spent significantly below zero. Consequently the snow almost melted and then re-froze to form coarse crystals which acted as crude corner-cube reflectors.

One night I was walking towards St Catz through the wooded area nearby. Street lights and the like produced very obvious halos of light when viewed at 180 degrees away from them. At a few places in my walk there were no sources of artificial light, only stars and Jupiter. I could still see a faint but clear halo with a darker circular centre which was antipodal to Jupiter. If I moved to put Jupiter behind a tree the halo disappeared.

Dr Sardonicus 2020-10-09 01:37

I surmised the "special circumstances" might also have included Jupiter being at or near its brightest. So, I looked up its dates of opposition (occurs about every 13 months) in years around 1980.

1976 November 18
1977 December 22
1979 January 24
1980 February 24
1981 March 25
1982 April 22

a1call 2020-10-09 03:56

Couple of related phenomena, one on a much grander scale. I have always been fascinated by the AntiSolar point but have never seen it 1st hand. I only know about it because I knew it had to exist and researched it years ago before internet was a thing.:smile:

[url]https://en.wikipedia.org/wiki/Gegenschein[/url]


[url]https://en.wikipedia.org/wiki/Heiligenschein[/url]

LaurV 2020-10-09 06:45

Yep, we didn't know about Sundogs either, or the "[URL="https://en.wikipedia.org/wiki/Diamond_dust"]diamond dust[/URL]" described in association with both the phenomenons. It was exactly what we saw on the sky (a second, smaller Sun).

Doing some "web research" since we posted here, we found out that these thingies are not so rare occurrences, but we didn't know about them, and we didn't see any "live" ever, it seems like they do not appear much in the areas we lived (it may be a latitude thing, forming the ice crystals is favored by colder climate, while the reflection/refraction depends on sun rays incidence. Whatever, we didn't see one, beside of all kind of rainbows, which is kinda similar, except the water is involved, and not the ice crystals, so we were quite mesmerized by it.

Thanks to everybody who posted links (quite interesting to read). We are a bit smarter today than we were yesterday (this assumes that we didn't forget in other areas more than we learned here, in the same time, which we have no idea if true or not :razz:)

xilman 2020-10-09 08:41

[QUOTE=Dr Sardonicus;559300]I surmised the "special circumstances" might also have included Jupiter being at or near its brightest. So, I looked up its dates of opposition (occurs about every 13 months) in years around 1980.

1976 November 18
1977 December 22
1979 January 24
1980 February 24
1981 March 25
1982 April 22[/QUOTE]Thanks. Historical weather records should be able to pin it down to within a couple of days.

Spherical Cow 2020-10-22 22:18

[QUOTE=bsquared;559257]I took these pictures in January 2019 on a windy -33F (-36C) degree day, on my way to work in the morning. [/QUOTE]

Very nice- those are some of the best I've ever seen.


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