Incredibly large halo around the Moon

[Chris Foltz]

Had the good fortune last night to witness one of the largest halos around the moon I've ever seen. It was so large, in fact, that I was unable to get it all into a single shot. It was most likely caused by very high cirrus clouds blowing over in advance of the storm system cranking up just to the west. Here are a couple of my favorites. These were taken about 1:30am today. Sorry the photo sizes are so large...

The rest of them can be found here...

http://photobucket.com/albums/a199/mizzouw...%20halo%20pics/

 

[Jeff Snyder]

I remember one from earlier this spring... It was very, very large, appearing to encompass from the 50% of the sky. Pretty awesome.

 

[Andrew Khan]

I saw one of those, while I was driving back for IN/KY/IL, it was a very pretty site!

 

[Bill Hark]

This brings up an obvious question: Is there any significance to the size or diameter of the halo? I suspect, there is some relationship to the size or shape of the cirrus ice crystals.

Bill Hark

 

[Scott Currens]

I also saw the impressive halo last nite.

Isn't a halo always at an angle of 22 degrees from the light source?

Scott Currens

 

[Mike Peregrine]

Yes - was just reading up on this online ... the ice crystals are generally hexagonal prisms that take in the light on one face, and refract it at 22 degrees from an opposing face, which is what determines the size of the halo.


Don't know why I can't get this link to complete (looks like that weird parenthesis thrown in there), so you'll have to copy & paste - - -

http://ww2010.atmos.uiuc.edu/(Gh)/guides/m...ce/halo/22.rxml

 

[Tim Stoecklein]

Might have something to do with out impeding snowflakes :wink:

Tim

 

[B Ozanne]

A common site on the summit of Mount Washington...halo around the sun: