Wednesday, July 15, 2009

The highest clouds of the world over Seattle


Above is a picture taken after sunset at Seattle's Shilshole Bay Marina by Joseph Marsh on Tuesday evening. Just clouds? Not quite...these are very special clouds that are the highest clouds on earth...noctilucent clouds.

These clouds are most commonly seen on clear nights north of roughly 50N during the summer months. They are located in the mesosphere at heights of roughly 50 miles above the surface. (Remember...the layers of the atmosphere are troposphere, stratosphere, mesosphere). These are ice clouds that form on dust, probably produced by meteors. Such clouds often have a silvery or bluish color, and a ragged look.

Want to see the clouds in the department time lapse imagery? Check out the following and wait until the very end, after sunset:

http://www.atmos.washington.edu/images/webcam0/movies/20090714.mov

So on the next few clear nights take a look during twilight and see if you can spot them.

17 comments:

micah said...

From downtown this morning, I saw some thick fog over Elliot Bay that was no higher than the half the height of the huge red cranes on Harbor Island. The sky was completely clear (since all the fog was below me in elevation).

I've never seen anything like that here on a summer day, and your blog was the first thing I thought of when I saw those clouds! Any idea why they formed on this particular morning?

spappyjones said...

These are some shots of the clouds over N. of Spokane

http://www.flickr.com/photos/12057715@N00/3723866070/in/photostream/

Picnicking in Dreamland said...

Magnificent! Here are more: http://spaceweather.com/nlcs/gallery2009_page13.htm?PHPSESSID=eql0n2mjlucmmgerlhht858i94

It's so amazing to see the rarities of a northern latitude. Now if only we get some clear nights this winter, perhaps the aurora will come forth....

Bill Kuhn said...

micah -

The fog this morning was extraordinary. When I awoke (in Montlake) about 5:45, there were no fog banks left - clear sky, but many windows fogged up.

I then drove my wife down to SeaTac, and by the time I got home around 6:45, the temp had dropped considerably, and we were encased in fog. All the way biking to work in Fremont, fog, cold fog.

Sure didn't seem like mid-July

Cliff Mass Weather Blog said...

Micah...if you want to see a nice time lapse of the fog/low clouds this morning, check out:

http://www.atmos.washington.edu/images/webcam0/movies/20090715.mov

Bill Kuhn said...

Thanks for the vid link, Cliff. Shows almost exactly what I was writing about (pretty much to the minute, in fact!).

My question - what caused the window fogging this morning? Very atypical, usually means a big temp diff between inside and outside?

thanx again.

JewelyaZ said...

I saw those clouds two nights ago while I was outside watering the garden and recognized them for what they were. I only knew about that kind of cloud thanks to a couple of hours I spent on the excellent spaceweather.com site that someone posted here a week or so ago.

VERY COOL!

Fluffyblue said...

I saw these clouds this morning at around 4 am in the northeast sky.

Kevin Purcell said...

Picnicking in Dreamland said: "Now if only we get some clear nights this winter, perhaps the aurora will come forth...."

You'll need more than clear nights for aurora. You need an active sun with sunspots too.

We're at the solar minimum now and waiting for sunspots to reappear. No aurora at this latitude (for another few years). This might also be a low maximum too given the current estimates.

But I'll take a look for the noctilucent clouds.

What time was the photo taken, Cliff? 9pm? 10pm?

Kevin Purcell said...

By watching the time lapse movie I answered my own question: what time to look?

In the movie they were apparent starting at 10:00pm (22:00), have highest contrast about 10:15 to 10:20 and disappear (i.e. the sun sets on them at about 10:25pm.

So that's sunset + 60 minutes to sunset + 90 minutes.

Remember the geometry has to be right to illuminate the 50 mile high clouds (after sunset so you can be sure your not seeing just high cirrus).

Look towards the setting sun and a little north.

The inverse will be true in the morning: 90 to 60 minutes before sunrise: 4am to 4:30am (just as the FluffyBlue describes!).

For cloud nuts the BBC just showed Gavin Pretor-Pinney's documentary Cloudspotting bases on his "international bestseller" The Cloudspotter's Guide. Very entertaining.

http://www.bbc.co.uk/programmes/b00k99th

Gavin Pretor-Pinney's runs the The Cloud Appreciation Society

http://cloudappreciationsociety.org/

Dunno if it will be out on DVD.

micah said...

Awesome video. It was definitely strange; I wish I'd snapped a photo of the fog over the water that otherwise hot morning.

forest said...

Looks like more this evening?

woody said...

In the time-lapse movie I thought it was cool to see the swirly wind directions - usually I think of the wind being from the north or south, but this had layers of both at once, then a definite northeast wind, then finally the solid notherly. Much more complicated than I expected.

woody said...

In the time-lapse movie I thought it was cool to see the swirly wind directions - I have always thought of the wind being from the north or south around here, but you could see that sometimes there were layers of northish and southish, then a definite northeast wind, and finally a solid northerly.

Reid said...

Here are a few photographs I took Wednesday night up in Mukilteo.

http://reidsphotos.blogspot.com/2009/07/noctilucent-or-polar-mesospheric-clouds.html

Lela said...

Wednesday PM we were having supper on our deck in Chimacum and observed what looked like evidence of planes falling out of the sky: contrails that at a certain, relatively close point, turned dark and spiraled downwards. Very strange. Any ideas?

Bob Harrington said...

Lela,

I think I got a photo of one of your contrails Wednesday evening while waiting for the NLC show to start.

http://bobqat.com/2009-07-15_Contrail.jpg

It really is just a jet contrail, lined up almost directly to the line-of-sight, and foreshortened by the distance and telephoto lens.

It looks to me like the jet was flying away towards the northwest, flying a 'great circle' route to Asia or beyond.

Bob ^,,^
Bobqat.com