Weather Blog

What were those cool clouds last week?

What were those cool clouds last week?
OK, I admit it. I was actually out of town last week (in Alaska -- dodging the September sun here. It was 55 and rainy up there, just the way I like it), but I wrote some generic weather blog entries ahead of time to keep the page going, thinking a week of sunshine while I'm gone wouldn't present me with much in the way of topical content.

Bzzzzt. Never underestimate Mother Nature's propensity to dazzle at any time. (Before I get too far, I wrote up some other blog entries below on some other events of last week, so there is some other new content besides this entry listed below.)

Far and away, the most e-mailed question was about those cool whispy clouds seen last Tuesday around sunset, like those seen above in that photo over Lake Tahuyeh taken by Bev Bruins.

They looked like mini tornadoes, but actually, it was just rain. The clouds themselves are officially called "Altocumulus Castelanus" and are apparently formed when you have a layer of moist air trapped between two layers of dry air -- sort of like a sandwich. The tentacle or "tornado" like fringe on the bottom is actually rainfall that is evaporating into the dry air below the cloud deck.  They're pretty rare but amazing to look at.

(And to answer another question, the term for when rain evaporates before it hits the ground is "virga" -- quite a few reports of that around that day too.

Here's another photo by Larry Brennan of Sammamish



Here is what they looked like on satellite image:



And to answer a second question in the email hopper -- apparently the sun was really bright red and large at sunset during the middle of last week. That was likely due to some smoke from wildfires in Oregon drifting north and giving the sun the red tinge.