Category Archives: Weather & Sky

Enchanting Sky and Flowers

Sunrise on 24 June 2021 (photo by Kate St. John)

26 June 2021

The sky was enchanting on Thursday morning while enchanter’s nightshade (Circaea lutetiana or perhaps Circaea canadensis) was blooming in Schenley Park.

Enchanter’s nightshade, Schenley Park, 25 June 2021 (photo by Kate St. John)

On 16 June, six of us were enchanted by mountain laurel and hundreds of pitcher plants blooming at Spruce Bog on top of Laurel Mountain.

  • Mountain laurel on Laurel Mountain, 16 June 2021 (photo by Kate St. John)

In the slideshow above, notice the leaf that’s wrapped and sealed into a tube. The structure was made by an insect. I don’t know which one.

p.s. Read more here about the enchanter’s nightshade name. Interestingly the plant is not in the nightshade family.

(photos by Kate St. John)

After The Storm

Sunset after the storm, 13 June 2021 (photo by Kate St. John)

Tuesday 15 June 2021

At 6pm on Sunday evening a violent thunderstorm blew through Pittsburgh with powerful wind gusts, hail and heavy rain.

Dave DiCello photographed the storm from the West End as it approached Oakland. The VA Hospital and the Cathedral of Learning are to the right of the lightning bolt.

Meanwhile my husband and I watched from our 6th floor apartment as a wind gust picked up the patio umbrella from the high-rise roof next door and blew it, Mary Poppins-like, until it crashed into our building. Then we saw no more as rain and hail battered our windows for half an hour, first from the north, then the east.

The tempest left behind flooding, downed trees, power outages, and a rainbow.

Rainbow after the storm, 13 June 2021 (photo by Kate St. John)

Yesterday morning I surveyed the damage after the cleanup had already begun. In a short walk I found trees down at Frick Fine Arts, Carnegie Library and Museum, and two small breaks on South Craig Street.

At Schenley Park the valley around Panther Hollow Lake was spared but the lake itself was full of flood water. This is by design. A flow control gate at the outlet holds back freshwater so that storms will not flood The Run.

Panther Hollow Lake holds back floodwaters from the storm, 14 June 2021 (photo by Kate St. John)

This morning the power was still out in parts of Squirrel Hill as I drove home from the grocery store.

My husband and I were fortunate. Our power never failed and that flying umbrella hit the wall below us and caused no damage.

p.s. The young Pitt peregrines are flying so well that they are hard to find. I saw both adults plus two of four juveniles on my Monday morning walk.

(photos by Kate St. John)

Why Are Clouds Flat On the Bottom?

21 May 2021

Discrete fluffy white clouds. When I photographed this field of rapeseed in Ohio I was struck that all the clouds are flat on the bottom. Why?

They look as if they are laid on a glass ceiling. The bottoms are at the same altitude. Here’s a similar sky in Australia.

Cumulus humilis clouds in New South Wales, Australia (photo from Wikimedia Commons)

These fair weather clouds are Cumulus humilis, “humble” clouds that are flat and wide.

If the rising air is strong enough they grow upward to become Cumulus mediocris

Cumulus humilis and mediocris (photo from Wikimedia Commons)

… and taller into Cumulus congestus which can end a fair weather day.

Cumulus congestus and cumulus mediocris (photo from Wikimedia Commons)

All of them have flat bottoms at the same altitude because …

The flat bottom of cumulus clouds defines the exact height at which a critical combination of temperature and air pressure causes water vapor within the rising current to condense into a visible cloud.

Chicago Tribune, Ask Tom about weather, 19 July 2015

The bottoms show where the dewpoint is.

A NOTE about the yellow field: Rapeseed (Brassica napus), in the mustard family, is grown for its oil-rich seeds. Cultivars with very low eruric acid become canola oil. “Rapeseed is the third-largest source of vegetable oil and second-largest source of protein meal in the world,” according to Wikipedia.

(photo by Kate St. John)

In the Family of Halos

22 May 2021

There were clouds on the eastern horizon when the sun rose in a spectacular sun pillar on Thursday morning 20 May.

According to Wikipedia (paraphrased):

The effect is created by the reflection of light from tiny ice crystals suspended in the air or in cirrus clouds.

The crystals are usually flat hexagonal plates that are oriented horizontally as they fall through the air. Each flake acts like a tiny mirror that reflects light sources positioned below it.

The presence of flakes at a spread of altitudes causes the reflection to be elongated vertically into a column. The larger and more numerous the crystals, the more pronounced this effect becomes. 

Wikipedia article on light pillars

Though it was 57 degrees F at sunrise that morning, the sky was cold.

Sun pillars have a lot in common with sun dogs. They are both in the family of halos.

Air Then and Now

50 million year-old spider and air trapped in amber (photo from Wikimedia Commons)

22 April 2021

If you want to know what the air was like 100 million years ago, look at the air trapped in amber. In 2013 scientists analyzed 538 samples and discovered that in the age of the dinosaurs there was less oxygen in the air than now. The concentration in the early Cretaceous period was only 10-15% compared to 21% oxygen today. It was similar to the available oxygen at Mount Everest Base Camp.

If you want to know what the air is like now in the U.S. check the 22nd annual State of the Air Report issued yesterday by the American Lung Association (ALA). Sadly, Pittsburgh is still in the top 10 of Bad Air cities for year-round particle pollution.

The State of the Air Report doesn’t even measure the rotten egg smell — hydrogen sulfide, H2S — that’s produced by U.S. Steel’s Clairton Coke Works and Edgar Thompson Works in Braddock.

High concentrations of H2S (widely recognized by its foul, rotten-egg odor) are registered all too often in the Mon Valley. In fact, so far this year there have already been 21 exceedances of Pennsylvania’s 24-hour average H2S standard – 13 at the Liberty monitor and eight more at the North Braddock monitor., State of the Air Report, 21 April 2021

This month has been especially bad. Here’s what it looked like last Sunday 18 April on Smell PGH’s crowd-sourced bad smell report.

In Pittsburgh, the nose knows.

That rotten egg smell (Tammany cartoon via Wikimedia Commons, text removed)

Read more about the air the dinosaurs breathed in this vintage blog: Ancient Air.

Read more about Pittsburgh air quality (Pittsburgh area air quality still gets failing grades) and what you can do about it at the Group Against Smog and

p.s. The scientific paper about the air-in-amber research is here:

(photos from Wikimedia Commons, Smell PGH screenshot from the app; click on the captions to see the originals)

Cleared For Take Off?

Volcanic eruption plume of La Soufrière, 9 April 2021 (photo from Wikimedia Commons)

21 April 2021

Twelve days ago Saint Vincent’s La Soufrière volcano began erupting after four decades of silence. Since 9 April it has blanketed the island with thick ash, forced the evacuation of 20,000 people, and ruined fresh water, homes, and farms. It has also caused a deep humanitarian crisis (see 5-minute British Channel 4 video at bottom) and killed untold numbers of local plants, animals and birds.

map of Saint Vincent and the Grenadines in the Caribbean (Wikimedia Commons)

The volcanic plume is also devastating the air, bad to breathe and dangerous for anything that flies. Saint Vincent’s airport closed when the eruption began while NOAA’s Volcanic Ash Advisory Center provides maps of Caribbean no-fly zones for pilots. The 10 April zones match the plume graph from NASA.

NOAA VAAC maps, Saint Vincent
Tracking La Soufrière’s plume (image from NASA Earth Observatory)

Though the disaster feels far from Pennsylvania it may affect our migratory birds that have not yet crossed the Caribbean from South America. Will the birds smell the plume and find a way to avoid it?

Airplanes will soon be cleared for take-off at Saint Vincents airport. I wonder if the birds will be, too.

This 8-minute video from Britain’s Channel 4 shows the devastation at Saint Vincents.

p.s. Click here for a video of satellite imagery showing the atmospheric effect of La Soufrière volcano.

(images from Wikimedia Commons, NOAA and NASA Earth Observatory)

The Worm Moon is The Crow Moon

American robin pulling up a worm (photo from Wikimedia Commons)

27 March 2021

You may have heard that tomorrow’s full moon at 2:50pm EDT (28 March 2021) is called the Worm Moon after the earthworm casts that appear as the ground thaws.

Did you know it’s also called the Crow Moon?

The more northern tribes of the northeastern United States knew this as the Crow Moon, when the cawing of crows signaled the end of winter.

NASA: The Next Full Moon is a Supermoon Crow Moon

Northern tribes didn’t have worms where they lived because the Ice Age wiped them out. Instead they noticed the change in crow behavior.

Nowadays we have earthworms that were accidentally imported from Eurasia so the Worm Moon makes sense to us.

In Pittsburgh the Crow Moon happens in December. 😉

Crows silhouetted against the supermoon, December 2017 (photo by Kate St. John)

Read more at The Next Full Moon is a Supermoon Crow Moon.

(photo from Wikimedia Commons and by Kate St. John)

Sights and Sounds of Early Spring

Sun pillar at sunrise, 6 March 2021 (photo by Kate St. John)

14 March 2021

Spring is coming! Our native trees are slow to bloom but cultivated flowers and amphibians are already active. There’s a lot to see and hear.

Above, on 6 March we were greeted by a sun pillar caused by ice crystals slowly falling through the air at sunrise.

A shagbark hickory lives up to its name in bright sunlight.

Shagbark hickory, Raccoon Wildflower Reserve, 12 March 2021 (photo by Kate St. John)

American basswood now has bright red buds that are still cautious about opening.

American basswood buds, Raccoon Wildflower Reserve, 12 Mar 2021 (photo by Kate St. John)

Cultivated European white willows have bright yellow twigs in March.

Cultivated willows turn yellow in early spring, Homewood Cemetery, 9 Mar 2021 (photo by Kate St. John)

Non-native crocuses are blooming so I hoped to see native snow trillium at Raccoon Wildflower Reserve on Friday, 12 March 2021. I did not find any, not even leaves. Was I too early or did the deer eat them?

However I was rewarded with the sound of frogs! Spring peepers and a few wood frogs called from the first vernal pool.

Peepers calling at Raccoon Wildflower Reserve, 12 March 2021

Wood frogs quacked in the second pool joined by a few solo peepers (hear that slow “creeeek” sound). In the video you can see the surface of the water moving with so many wood frogs.

Get outside while the sun’s shining. There’s more spring to come!

(photos audio and video by Kate St. John)

A Chunk of Comet Killed the Dinosaurs

Incoming! The event that killed the dinosaurs (screenshot from Harvard University video)

24 February 2021

Ever since the early 1980s when Luis and Walter Alvarez discovered that the Chicxulub Crater in the Yucatan and the extinction of the dinosaurs were caused by the same event, we’ve talked about the “asteroid” that killed the dinosaurs. Recently two Harvard researchers took a new look at the composition of Chicxulub rocks and the physics of comet behavior and revised that conclusion. It wasn’t an asteroid that killed the dinosaurs. It was a chunk of comet!

Asteroids live in the main belt of the inner solar system located between Mars and Jupiter. Comets are from the Oort cloud of interstellar space.

Logarithmic scale distance of the Oort Cloud from the rest of the Solar System. Voyager 1 location in 2013 (image from Wikimedia Commons)

The video below explains how a piece of comet could break off and cause the Cretaceous–Paleogene extinction … and how soon one could hit us again. By the way, Jupiter is involved.

Yow! Oh no!

Illustration of an unusual association of hadrosaur and therizinosaur from tracks found in Denali National Park, Alaska (illustration by Karen Carr via Wikimedia Commons)

A chunk of comet killed the big dinosaurs. Fortunately we still have the little ones with us … Birds!

(screenshot at top from Harvard University video, remaining photos from Wikimedia Commons; click on the captions to see the originals)

Will We See A Moon Ring This Winter?

22 degree halo around the moon, Croton-on-Hudson, 30 Dec 2020 (photo from Wikimedia Commons)

30 January 2021

In winter when the moon is full and the sky is almost clear with a thin layer of cirrus clouds you may see a halo around the moon. The ring has a radius of 22o so it’s called a 22o halo, a moon ring, or a winter halo.

The conditions for a moon ring are relatively rare in Pittsburgh: a full moon + a clear sky + thin cirrus clouds whose ice crystals refract and reflect the moonlight. Seeing the halo is a matter of perspective based on where you stand and which ice crystals refract/reflect for you.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you. “What makes a Halo Around the Moon”

On Wednesday night, 27 January, the nearly-full Wolf Moon rose before sunset hidden by Pittsburgh’s overcast sky. By 8pm the clouds were breaking up and made an iridescent halo around the moon. It was not a true 22o halo but it cast enough light to make shadows. All I have to show for it is this very blurry photo.

Fuzzy photo of full Wolf Moon with iridescent cloud ring, Pittsburgh, 27 Jan 2021 (photo by Kate St. John)

The next morning at 4:15am the sky was absolutely clear and the moon was shining brightly without a ring. I was disappointed because the clear sky was wasted on us while Pittsburgh slept. Three hours later the sun rose in an overcast sky.

Last night was the same — a nearly full moon and an absolutely clear sky. No moon ring.

The Wolf Moon is waning and winter will too. The next full moon on 27 February is our last chance at a Winter halo. The full moon after that — 28 March — will be in the Spring.

(photo at top from Wikimedia Commons; click on the caption to see the original. blurry photo by Kate St. John)