These pretty clouds won’t rain … yet. They drift by in thin shields with gaps between and when they thicken they look like buttermilk (click here to see).
These are altocumulus clouds that form in the mid-level of the cloud deck, between 6,500 and 20,000 feet. Their thicker version is called a mackerel sky because the effect resembles the scales on a king mackerel.
Weather sayings confuse me about the message these clouds are bringing. One poem says, “Mackerel sky, mackerel sky – never long wet, never long dry.” Worst case: These are overtaken six to eight hours later by different clouds that bring rain.
On the day I took this photo I was outdoors for six hours and yes, these happy clouds were followed by thick, potential rain clouds.
A new study on the future of climate change in arctic Alaska spells bad news for gyrfalcons in the U.S.
By 2050 the mean annual temperature in northernmost Alaska is expected to rise 3.10C (5.560F). This will usher in a host of changes to ice, coastlines, tundra, plants and animals. What will happen to the area’s breeding birds?
Scientists from the Wildlife Conservation Society, assisted by experts on each species, assessed the future of 54 of arctic Alaska’s breeding birds. The goal was to prepare wildlife and land managers for climate change and ultimately develop plans to mitigate the effects if possible.
The study found that two species, gyrfalcons and common eiders, are highly vulnerable to the anticipated warming and likely to experience dangerous declines. Seven others are moderately vulnerable: brant, Steller’s eider, pomerine jaeger, yellow-billed loon, buff-breasted sandpiper, red phalarope and ruddy turnstone.
Gyrfalcons are specialists and climate change is going to be rough on their niche.
They nest on coastal cliffs in microclimates that are a rare commodity in northern Alaska. South-facing cliffs may become too hot, limiting the number of suitable nest sites.
At the start of breeding gyrfalcons eat ptarmigan almost exclusively. When ptarmigan populations are low gyrfalcons won’t breed at all. When climate change affects ptarmigans it will hurt gyrfalcons.
The gyrfalcon’s hunting style relies on open tundra but as the arctic warms shrubs will grow in formerly open land.
Spring storms are expected to increase. Unfortunately this will cause nest failure for gyrfalcons who require dry weather to hatch their eggs.
With all these cards stacked against them gyrfalcon numbers are expected to drop considerably from today’s 250 breeding pairs.
But the report has a silver lining. There will be more seed eaters: savannah sparrows, Lapland longspurs, white-crowned sparrows, American tree-sparrows and common redpolls.
Much as I like redpolls, I don’t want to trade them for gyrfalcons.
(photo from Wikimedia Commons. Click on the caption to see the original.)
p.s. The report was careful to point out that the study only applies to arctic Alaska, not to all breeding ranges. The photo above was taken in western Greenland.
Eruption of Sarychev volcano seen from the International Space Station, 12 June 2009 (photo from NASA)
3 April 2013
Imagine seeing this outside your window!
On June 12, 2009 the International Space Station was flying over the Kuril Island chain in the northwestern Pacific when they witnessed the eruption of Sarychev peak, an active volcano on Russia’s Matua Island.
Because the eruption had just begun, brown ash and steam was still rising in a mushroom cloud that had punched a hole in the cloud cover above it. Meanwhile, dark brown ash rolled low to the ground, probably a pyroclastic flow of hot gas and rock up to 1,850oF (1000oC) and traveling at 450 mph!
The ash had just begun to spread out in the sky (light brown at top left and right). Soon commercial air traffic was diverted to avoid engine failure from this abrasive particulate in the upper atmosphere.
The astronauts were lucky to see this eruption as it began.
Nature makes an impressive mushroom cloud.
(photo from the International Space Station, NASA)
There we were, focusing our attention on an asteroid that was going to miss the Earth when Bang! A real live meteor zipped low over Russia yesterday morning, 15 February 2013.
The meteor taught me a lot more than the asteroid. After it lit the sky, made an explosive boom, blew out windows, and injured more than 1,000 people I learned from NASA:
Its light was brighter than the sun.
Its contrail was 300 miles long. (That’s the distance from Pittsburgh to Philadelphia).
Eyewitnesses said the sonic boom lagged by three minutes … just long enough for everyone to go to their windows to watch.
The meteor was about the size of a bus (55 feet) but it weighed 10,000 tons –> 1,400 times heavier than a bus.
The atmosphere really did help after all. When the meteor exploded it was still 12-15 miles up. At least twice as high up as a jetliner.
If it was only the size of a bus and 2 to 4 times higher up than a jet, why did it cause such a problem? Well, it was traveling at 40,000 mph!
So, hold onto your hats. It’s the stuff we aren’t worried about that gets us.
This video from The Telegraph UK shows dashcam video and explains what happened.
p.s. 16 Feb 2013: The meteor also taught me two things about Russian culture: (1) Russians have dashboard cameras in their cars to protect against corrupt policemen and disputed traffic accidents, and (2) They have already made a joke about it, quoted from the Houston Chronicle: “The meteorite was supposed to fall on Dec. 21, 2012 — when many believed the Mayan calendar predicted the end of the world — but was delivered late by Russia’s notoriously inefficient postal service.”
(photo of the Chelyabinsk meteor’s trace from Wikimedia Commons; click on the caption to see the original)
Even when scientists develop an answer to why something happened, they still test the idea to make sure they’re right.
That’s what happened with the Great Arctic Cyclone of August 2012.
Last August a rare, massive cyclone formed in Siberia and swirled out over the Arctic Ocean for days. During its transit the sea ice disappeared faster than anyone had ever seen. (See the swirl here.)
By September Arctic sea ice was at an all time low. Some said the cyclone caused the lowest ice extent since record-keeping began. Did it? Or would the ice have melted anyway due to warm temperatures?
Scientists at the University of Washington’s Applied Physics Laboratory ran two computer simulations of last summer’s Arctic weather. One matched the actual weather. The other included everything except the cyclone.
The result showed that yes, “the effect is huge in the immediate aftermath of the cyclone, but after about two weeks the effect gets smaller. By September, most of the ice that melted would have melted with or without the cyclone,” said lead author Jinlun Zhang.
Why? Because of mixing.
Back in September most thought that the wind broke up the thin ice or pushed it into a warmer part of the ocean. Since then scientists have learned that the ocean underneath the ice is like a layered parfait. Just below thin ice is a layer of ice-cold fresh water. About 65 feet down is a layer of salty water warmed by the sun. The cyclone stirred the parfait. The ice was exposed to the warm water beneath and it melted.
The cyclone did cause the ice to melt 10 days sooner, but in the end it made less than 5% difference in the ice extent.
So yes, the sea ice melted because it was hot last year.
Click on the photo to read more about the study in Science Daily.
I know almost nothing about fluid dynamics but my article about wingtip vortices piqued my interest in the subject.
Last weekend I learned about this amazing phenomenon, the von Kármán vortex street, animated above by Cesareo de La Rosa Siqueira.
Von Kármán vortex streets occur when a fluid flows past a stationary object and generates a long line of vortices that swirl in opposite directions. The phenomenon was named for Theodore von Kármán, the man who described it, and is probably called a street because it looks like one.
We usually don’t see von Kármán vortex streets in the air but it’s important that engineers plan for them. If a tall structure is uniformly straight or uniform structures are grouped too closely the vortices can make them fall down. That’s what happened in November 1965 when three of the eight Ferrybridge cooling towers collapsed in high winds. They could individually withstand the wind speed but not the vortex.
On a small scale, von Kármán vortex streets make wires sing in the wind. On a large scale they’re visible from outer space when clouds blow past a tall island.
Here’s a picture taken from the space shuttle that shows cloud cover blowing past Rishiri Island, Japan. When the wind encounters Mt. Rishiri the clouds form a von Kármán vortex street on the downwind side.
(Vortex animation by Cesareo de La Rosa Siqueira via Wikimedia Commons. Space shuttle photo from NASA via Wikimedia Commons. Click on the images to see the originals)
The long spate of cold weather froze all our ponds and lakes. Even the rivers were beginning to freeze until Monday’s warmth reversed the trend.
Don’t expect to see a lot of birds at Lake Arthur right now. Waterfowl who rely on open water for food or to get airborne have left for open water. Some are at our rivers, most have left town completely.
This female bufflehead was on the other side of the U.S. — at Bosque del Apache, New Mexico — when Steve Valasek took her picture.
No, she didn’t leave Pittsburgh for New Mexico, but Steve did.
As I write this morning before dawn, the wind is whipping around the house as a winter storm approaches from the west.
If I was at the roof peak I’d be blown away. The wind is even faster up there (see red lines at top) where it converges to clear the house.
Outside my window on the downwind side, the air is swirling in updrafts like the turquoise lines at left.
I suppose I could find a few calm spots within the swirls if I went outdoors to experiment, but it’s not worth it. At particularly gusty moments I hear garbage cans rattle down the alley in the dark.
(diagram by Barani on Wikimedia Commons. Click the image to see the original)
Like a three-strand necklace of pearls, this composite photo shows the sun’s position hour by hour at the summer solstice, the vernal equinox, and the winter solstice.
It was taken at the same location in Bursa, Turkey over a period of six months by award-winning amateur astronomer and night sky photographer Tunç Tezel, a member of The World At Night.
The top strand is the sun’s transit during the summer solstice in June, the longest day of the year. You can tell the sun was up for 15 hours because there are fifteen pearls on that strand.
The middle strand was taken during the equinox when every place on earth has 12 hours of daylight.
The lowest strand was taken on this day, the winter solstice, when there are 9 hours of sunlight in northern Turkey.
There are nine hours of daylight in Pittsburgh today, too.
Northern Turkey and western Pennsylvania are on approximately the same latitude so these sun tracks are what we see here in Pittsburgh.
The whole world shares the same sky. We all can see the sun as pearls.
Today’s weather is supposed to be “partly sunny” but in winter that can mean the sun looks like this for part of the day.
This photo could have been taken anywhere in western Pennsylvania in early December. Brown fields, bare trees, power lines, crows. Can you guess where it was taken?
Click here and then on the Google Maps link to see the photo’s location, or click on the image to read the description. You’re in for a surprise.
(photo by Pauline Eccles via Wikimedia Commons. Click on the photo to see the original)
p.s. The coordinates are 51° 53? 50.63? N, 2° 29? 38.14? W
