An article about ice on a very icy day, 8^oF and falling.

Considering how often the temperature has fluctuated in Pittsburgh this winter I’m surprised we haven’t seen more glaze ice.

Glaze ice is the name for the icy coating caused by freezing rain or freezing drizzle. If the accumulation is small, the effect is beautiful and the electricity stays on. The photo above from Wikimedia Commons is more beautiful than my own below.

When glaze ice is 1/4 inch thick or more the Weather Service calls it an ice storm. A quarter of an inch doesn’t sound like much but it’s so heavy that it weighs down the trees and they fall on power lines, streets, parked cars and houses. Power lines and power towers can fall, too. According to Wikipedia, “just one quarter of an inch of ice accumulation can add about 500 pounds (230 kg) of weight per [power] line span.” No wonder things come crashing down.

In January 1998 I wasn’t in Maine for the Great Ice Storm but I remember its results quite vividly. We visited central Maine in September and there were still broken trees everywhere. Folks who lived through it said they were without power for weeks. Everyone was stuck near home — couldn’t drive anywhere — so the radio stations connected people by announcing supplies and requests for help. Everyone pulled together.

The Great Ice Storm of January 1998 was even worse in upstate New York and Canada. Here are four photos from NOAA.

Pretty as glaze ice is, I’m glad to do without it.

(photo credits: Japanese maple glaze ice from Wikimedia Commons, glaze ice in Pittsburgh by Kate St. John, photos of the Great Ice Storm of 1998 from NOAA, 10th Anniversary. click on the captions to see the originals)

Let’s appreciate clouds. Tuesday January 22 was an especially good day for them.

After a beautiful red sunrise the sky cleared enough to reveal thin, wavy clouds flowing overhead. The National Weather Service said these clouds were at 11,000 feet — “alto” height, not cirrus height — but they really looked like this cirrocumulus undulatus photo at the International Cloud Atlas. Notice the feathery details in the photos above. (The four slides show two in normal color and two enhanced for contrast).

Cirrus clouds indicate a change in the weather. So did the red sunrise, photographed by Dan Dasynich. “Red sky at morn, sailors forewarn.”

Almost clear on Tuesday we had rainy, foggy weather the next day. The clouds told us it was coming.

(slideshow photos by Kate St. John, sunrise by Dan Dasynich)

Have you been appreciating clouds this week? It’s been hard to do because it’s been so overcast but …

On Throw Back Thursday, read about the cool clouds I saw on a single day in January 2012 in this blog post: Atmospheric Effects.

Learn more about clouds at the Cloud Appreciation Society.

(photo by Kate St. John)

A week ago, 7 Jan 2019, the National Weather Service said the sky was clear at Pittsburgh International Airport but I have proof that at that moment it was overcast in the East End.

Not only was it overcast but the clouds were doing something special near the Cathedral of Learning. See that wrinkle? Is that undulation? Or is it the beginning of an asperitas formation?

Asperitas clouds are newly named, the first formation to be added to the International Cloud Atlas in 66 years. They were proposed by the Cloud Appreciation Society in 2009 and accepted in 2017. The atlas goes back to 1896 so this is a big deal.

This video of asperitas clouds in Tenerife, featured by the Cloud Appreciation Society, shows how fascinating these clouds can be.

Thick clouds say “Pittsburgh in winter” all over them. Stratus (low) and altostratus (mid-level) are our specialty but we also have altocumulus undulatus, cumulus fractus and sometimes even mammatus. Click to see what they look like.

Yes, we have overcast skies (tell me about it!) but there are cool things above us if we just take the time to look. Watch the video to get in the mood (exciting background music!).

C’mon, Pittsburgh, it’s time to appreciate clouds!

(photo by Kate St. John, video from skyport.com.es on YouTube)

p.s. Did you know that clouds have a genus and species? At the bottom of this webpage is a cloud diagram that shows genus by height. Explore the International Cloud Atlas.

p.p.s. The sun is at the top edge of my photograph. Do you see it?

9 January 2019

Here’s a form of ice we’re unlikely to see in Pittsburgh because our weather is rarely cold enough and it’s often overcast.

Diamond dust is clear-sky precipitation that looks like tiny diamonds in the air, falling through a ground-level cloud. The conditions for producing diamond dust are very specific:

• The temperature has to be well below freezing — best at -13F or lower.
• The cloud must be made of ice. It’s not a freezing fog that started wet and turned icy.
• The cloud is in a clear sky and the sun is shining. That’s how you see the diamonds.

The best place to find diamond dust is in Antarctica where it falls 316 days of the year. Otherwise you have to be in the right place at the right time. Bundle up!

Bonus Question: Diamond dust is not associated with a pogonip. What’s a pogonip?

(video “Diamond Dust in Bellevue Washington” from Wikimedia Commons; click here to see the original)

Winter is an excellent time to see sun dogs, one of the many atmospheric optical phenomena caused by ice crystals in the air.

Sun dogs, also called parhelia, are bright spots to the right and left of the sun on the same horizontal level. If you know how to measure angles in the sky you’ll find them at 22 degrees from the sun, sometimes with rainbow colors.

Sun dogs are best seen when the sun is near the horizon but in Pittsburgh clouds often obscure one sun dog or even the sun itself. Pictured above is a lefthand sun dog, pictured below is one on the right. You can tell, even without seeing the sun, because the red end of the rainbow is nearest the sun.

If you’re really lucky you’ll see the sun between two very bright sun dogs. The “three suns” effect shows the origin of their name in Greek mythology — Zeus (the sun) walking his two dogs.

In the old days, three suns were considered an omen and not a good one. During the Wars of the Roses (England’s civil wars in the late 1400’s), the future king had to convince his panicky troops that three suns meant good news.

The prelude to the Battle of Mortimer’s Cross in Herefordshire, England in 1461 is supposed to have involved the appearance of a halo display with three “suns”. The Yorkist commander, later Edward IV of England, convinced his initially frightened troops that it represented the three sons of the Duke of York, and Edward’s troops won a decisive victory. The event was dramatized by William Shakespeare in King Henry VI, Part 3.

Wikipedia entry for Sun dog

Look up for birds on a cloud-skimmed winter day and you may see “dogs” in the sky.

(photos from Wikimedia Commons; click on the captions to see the originals)

Though this prediction is old news it will affect us very soon. It looks like Pittsburgh will have normal weather in the next three months, whatever that means in these crazy climate days.

According to NOAA’s precipitation outlook (above), Pittsburgh has an equal chance of being exceptionally wet or dry during January through March 2019.

The big news, but not for Pittsburgh, is that it’s going to be incredibly warm in western North America — especially in the Pacific Northwest, Alaska and Canada — and colder than normal in the Southern Appalachians. This is due to climate change and a developing El Niño in the eastern Pacific.

I won’t mind less rain in the next three months. We had record-setting rainfall in 2018: 57.83 inches, which is 19.64 inches — or 51.4% — above normal!

It won’t be so wet in early 2019. Maybe.

For more information and an interesting visual see the forecast at WeatherNation TV.

(maps of long range seasonal predictions from NOAA)