Wednesday, August 17, 2016

Glory and the Space Needle

Yesterday morning at the top of the Space Needle dawned sunny with low clouds on the horizon (see image), but around 7 AM low clouds pushed into Seattle, reaching the upper reaches of the Needle (shown below)

6 AM
 7AM
8:30 AM
 

But something beautiful and subtle occurred as the low clouds extended toward the Space Needle:  a glory, characterized by colorful, concentric rings.  Here are a few shots from the SpaceNeedle cam: 




It is not rare to see glories when flying above clouds when the sun is high in the sky.


Glories are optical effects that occur when you have the right configuration of sun and clouds. They result when light is scattered back to the viewer by a field of relatively uniform, small cloud droplets and is always opposite the sun (centered at the anti-solar point), just as the shadow of an object (like the Space Needle or aircraft) would be.   It is possible to realistically simulate the generation of glories using the equations describing electromagnetic waves and their interactions with droplets (Mie Scattering) as shown below (the upper left corner is the simulation):


Keep your eye out for glories next time you are flying.


8 comments:

jno62 said...

In Montana we used to call these Sun Dogs. Same thing?

Ansel said...

Hi Cliff: In your book, a graph indicates that, on average, the wind around the sound tends to peak around 3 PM. But, I am often frustrated when I go sailing: Yesterday, for example, there was (in the vicinity of Everett) little wind over the water until 4 PM. I returned at 6:00, when the sea breeze was so strong I rammed the dock trying to manage an oblique cross-wind. Often, it will still be quite strong at sunset.

Anyone care to comment: Why is there such a long lag between the daily heating and the sea breeze development? Seems to me that the sea breeze ought to develop around 10:00 when the land is clearly warmer than the Strait, and die at about sunset.

Neil Gordon said...

Hi Cliff - I was really interested to see in one of those images that there is a fog bow as well as a glory. This is similar to an image I captured from the top of Little Mount Ida in the South Island of New Zealand in June - now one of the finalists for the 2017 WMO calendar. Viewable via Facebook at this (long) link: https://www.facebook.com/71741701887/photos/a.10154002170001888.1073741851.71741701887/10154002288011888/?type=3&theater

Eric said...

It was really a treat to hear you speak on climate change in Port Angeles last night. Thank you for making the trek!!

Beth Niquette said...

These photos are absolutely stunning. I have seen some beautiful round rainbows before--but none like these. They are so beautiful. Thank you for your explanations. I especially liked the one with your airplane in the middle of it.

Organic Farmer said...

I am under the impression the afternoon sea breeze is tidal. Heating from a clear day combined with an inbound tide.

Mark said...

Climbers (and others) call these "Brocken spectres", which I've always found more evocative!

Ari Blenkhorn said...

@jno62 -- Different, but related. Sun dogs ("parhelia") are formed by ice crystals, and they appear near the sun. Glories are formed by liquid droplets, and they appear around the exact opposite point of the sky from the sun. http://www.atoptics.co.uk/halo/parhelia.htm

@Mark -- They go together. The Brocken spectre is the shadow of the observer in the middle of the glory. http://www.atoptics.co.uk/droplets/globrock.htm

@Cliff Mass -- may I have permission to use these images in my research? I'm a computer science PhD student developing faster methods of simulating glories, coronas, and related atmospheric phenomena. Thanks!