Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: John9929 on August 15, 2008, 03:39:25 pm



Title: Lunchtime Sun Halo.
Post by: John9929 on August 15, 2008, 03:39:25 pm
Got this beauty of a Sun Halo and UTA at lunchtime before the thicker cloud rolled in to spoil it.
The colours were so intence I have rarely seen one so bright.
(http://i38.tinypic.com/118zr78.jpg)


Title: Re: Lunchtime Sun Halo.
Post by: martinastro on August 15, 2008, 10:25:11 pm
That's a very nice image and striking example of a good Sun halo. Intense UTA!. I take it that's a contrail running through the halo from the R?.

Nice  :)


Title: Re: Lunchtime Sun Halo.
Post by: Paul on August 16, 2008, 09:08:36 am
John that's excellent - very colourful!

P.


Title: Re: Lunchtime Sun Halo.
Post by: Steveo74 on August 16, 2008, 10:24:42 am
Great capture John! Very intense, lens flare adds to the effect...  ;D


Title: Re: Lunchtime Sun Halo.
Post by: Roman White on August 20, 2008, 08:09:59 pm
Great capture, John. I rarely see a sun halo photo with cumulus together.

I'm sorry to ask, what is UTA?  ???


Title: Re: Lunchtime Sun Halo.
Post by: John9929 on August 20, 2008, 09:17:48 pm
Thanks Roman, ask away no problem. It stands for Upper Tangent Arc, though the one in the image was quite straight instead of  the usual "winged" type. This link may be useful http://www.atoptics.co.uk/halo/column.htm


Title: Re: Lunchtime Sun Halo.
Post by: Roman White on August 21, 2008, 10:37:41 am
Thanks for the answer John. But I can't see nothing like this in your image  ??? (http://i34.tinypic.com/avr78h.jpg)


Title: Re: Lunchtime Sun Halo.
Post by: John9929 on August 21, 2008, 11:22:09 am
"though the one in the image was quite straight instead of  the usual "winged" type.


Title: Re: Lunchtime Sun Halo.
Post by: martinastro on August 21, 2008, 10:49:47 pm
Roman, on many occasions a UTA will appear as a straight bar or obvious enhancement at the very top of the 22 degree halo. The 'wings' form when the Sun is at the correct altitude above the horizon and look very dramatic. If you mentally chop the wings off the sample image until you are left with a straight bar, this will match up well with John's image. Hope this helps, and I hope you catch one soon!

Nice image John.


Title: Re: Lunchtime Sun Halo.
Post by: Roman White on August 23, 2008, 09:34:38 am
Roman, on many occasions a UTA will appear as a straight bar or obvious enhancement at the very top of the 22 degree halo. The 'wings' form when the Sun is at the correct altitude above the horizon and look very dramatic. If you mentally chop the wings off the sample image until you are left with a straight bar, this will match up well with John's image. Hope this helps, and I hope you catch one soon!
As I have noted for many years, they appear more often in winter (early spring), when there are sometimes several days with alot of Ci/Cs.
Well, I do not remember any sun halo in summer.  :(


Title: Re: Lunchtime Sun Halo.
Post by: brianb on August 23, 2008, 09:50:33 am
Quote
Well, I do not remember any sun halo in summer.
You do tend to notice the haloes, mock suns etc. more when the sun is lower in the sky. But I get the impression that, here in Northern Ireland, they're not more likely at one time of year than another ... we get loads of cirrus throughout the year, sometimes (as for instance last night) it is very obvious that this cloud is smeared out jet contrails, and we have the misfortune to live underneath one of the busiest air routes in the world - all the jets between Western Europe and the USA pass overhead.

Thin high cloud allows solar heat in but traps the escaping radiation from the ground. Hence it increases the greenhouse effect - it's been estimated that a jet aircraft leaving a persistent contrail contributes at least ten times as much global warming that the effect of burning the fossil fuel has. The pity is that, by flying lower and slightly slower, the aircraft would use a few percent more fuel .... surely worth the investment for the sake of a large reduction in climate change and the beauty of the clear night sky.


Title: Re: Lunchtime Sun Halo.
Post by: Roman White on August 23, 2008, 10:19:21 am
You do tend to notice the haloes, mock suns etc. more when the sun is lower in the sky. But I get the impression that, here in Northern Ireland, they're not more likely at one time of year than another ... we get loads of cirrus throughout the year,
Not exactly. I tended to notice that cirrus (here in Poltava) are a usual thing on a clear winter day, but a bit rarer during autumn/spring, and much rarer during summer.

Well, I speak about something like this one, captured in early March
(http://s57.radikal.ru/i155/0808/c8/abec2477d77c.jpg)

sometimes (as for instance last night) it is very obvious that this cloud is smeared out jet contrails, and we have the misfortune to live underneath one of the busiest air routes in the world - all the jets between Western Europe and the USA pass overhead.

Thin high cloud allows solar heat in but traps the escaping radiation from the ground. Hence it increases the greenhouse effect - it's been estimated that a jet aircraft leaving a persistent contrail contributes at least ten times as much global warming that the effect of burning the fossil fuel has. The pity is that, by flying lower and slightly slower, the aircraft would use a few percent more fuel .... surely worth the investment for the sake of a large reduction in climate change and the beauty of the clear night sky.
Unfortunately, it's truth.  :( Jet aircrafts is another serious reason of global warming. I think it is necessary to reduce an amount of flights.