17 November 2022

Last weekend Chris Randall @ultrapeakschris tweeted a video of a shadowy figure walking in step with him in the fog. At first he thought it was another person. Instead it was a Brocken specter with a faint rainbow halo called a glory.

Spooky!

My first Brocken Spectre. Creepy to see it out the corner of my eye and think it was someone else moving pic.twitter.com/j38PhwGZqE

— Chris Randall (@ultrapeakschris) November 13, 2022

Wikipedia describes: A Brocken spectre is the magnified shadow of an observer cast in mid air upon any type of cloud opposite a strong light source (such as the sun). If the cloud consists of backscattered water droplets, a bright area and halo-like rainbow rings called a glory can be seen around the head or apperature silhouette. The phenomenon was named for Brocken Peak in Germany where it frequently occurs.

Sometimes the specter appears to hover in the sky like an angel as did this one with a triple glory that appeared to a mountain climbing team in Tajikistan.

Perhaps you’ve seen a Brocken specter from an airplane. I have, but I didn’t know what it was called.

And finally, you can create a Brocken specter in nighttime fog if you work at it. The caption on this photo says: “On an exceptionally foggy night, I parked my car at one end of the parking lot, facing into the lot, and covered one headlight with a floor mat. Standing before the uncovered light, I photographed the shadow that I was thus casting into the fog : a Brocken spectre.”

Who’s there in the fog? It’s you!

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

16 November 2022

Far, far away at the edge of our solar system there’s a spherical cloud of icy objects with an inner cloud like a bicycle spoke reaching toward the Sun. No one’s ever seen it. It’s the home of comets.

The Oort cloud is the theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). It is divided into two regions: a disc-shaped inner Oort cloud (or Hills cloud) and a spherical outer Oort cloud.

— Wikipedia: Oort cloud

The Hills cloud, or inner Oort cloud, contains roughly 5 times as many comets as the outer ring.

Long-period comets (which take more than 200 years to orbit the Sun) probably come from the Oort Cloud, which is sometimes described as a “cometary reservoir.””

— NASA: Oort Cloud overview

It’s the home of Comet Hale-Bopp which appeared in 1997 and will return to the inner Solar System around the year 4385.

Hale-Bopp is out there with the planetesimals, minute planets believed to be composed of cosmic dust grains that accumulated with many others under gravitation to form a planet.

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

p.s. an AU is an Astronomical Unit = the distance from Earth to Sun in one Julian year (365.25 days).

8 November 2022

This week southwestern Pennsylvania witnessed many atmospheric effects from clear skies to troubled clouds, rainbows and a total lunar eclipse. Here are the stories behind six pictures.

• Total lunar eclipse, 8 Nov 2022, 5:29am, photo through my birding scope. The sky was hazy and I am terrible at digi-scoping so by the time I got a decent shot of the moon it was leaving my view. But you get the idea.
• Atmospheric optics around the sun, 5 Nov 2022, 9:20am, Yellow Creek State Park, PA. Ice crystals in the clouds produced two sun dogs, a 22 degree halo, and a circumzenithal arc (upside down rainbow at top). Click on the links to read about each phenomenon.

• Layers of troubled clouds, 5 Nov 2022, 5:45pm: Later that same day two layers of clouds raced overhead in gusty wind. The lower layer threatened rain at the horizon while the upper layer glowed in sunlight.

• Light mist over the Monongahela River at Duck Hollow, 3 Nov 2022, 10am.

• Rainbow over Pittsburgh, 6 Nov 2022, 1pm: On Sunday I hiked at Hays Woods with Linda Roth (in foreground) and the 40 Acres AKA Hays Woods Enthusiasts. We got caught in a brief downpour but there was a Big Sky reward: a beautiful rainbow.

• The sky glows before sunrise on a clear day, 7 Nov 2022, 6:27am.

Keep looking up for more atmospheric effects.

(photos by Kate St. John)

22 October 2022

Pittsburgh skies put on a show in mid October.

On the 15th feathery contrails were pushed by high winds at 30,000 feet. We could not see them at dawn because of the lumpy clouds.

The next day the wind dropped, a temperature inversion set in, and rotten-egg smog gathered in the Monongahela Valley, below.

Temperature inversions are typical in October and November when warm air above traps cold air at the ground, filling the valleys with haze or fog. In Pittsburgh the pollution from US Steel Clairton Coke Works is also trapped, intensifying the rotten egg smell of hydrogen sulfide (H2S) in the Monongahela Valley.

Weather or not, US Steel Clairton always emits these pollutants. The 16th’s stinky haze capped more than ten days of unusually terrible air pollution from USS Clairton(*). Here’s how bad it was: How Bad has Air Quality Been? H2S Was Below PA Standard For Only 3 Hours This Week. (Note: H2S level is supposed to be below the standard to keep our air clean.)

The air smelled better October 17-20 including on this beautiful morning of October 20.

Yesterday’s pollution was pretty bad. Hoping for better air.

(*) US Steel’s Clairton Coke Works is the largest coking facility in the U.S., baking coal to make coke for steel production. Coking removes coal’s impurities by turning them into gases including stinky hydrogen sulfide (H2S). In March 2022 Allegheny County Health Department reported that “Based on all available data and resources, H2S exceedances that occurred at the Liberty site during the period of Jan. 1, 2020, through March 1, 2022, can be attributed entirely to emissions originating at US Steel’s Clairton coking facility.”

(photos by Kate St. John)

13 October 2022

Today is Thursday, Thor’s Day, or Jove’s Day. We’ll celebrate with some quick facts about Jupiter.

The Romans named the fifth day of the week dies Jovis (“Jove‘s Day”) after the planet Jupiter. In Germanic mythology, Jupiter is equated to Thor, whence the English name Thursday for the Roman dies Jovis.

— From Wikipedia: Jupiter

Jupiter was big in the news last month when on 27 September 2022 the planet was at its closest, brightest and best in 70 years. On that date the Earth flew between Jupiter and the Sun, putting Jupiter in opposition and in bright sunlight as it rose at sunset.

Three days later it rose after sunset so the sky was dark showing off Jupiter’s four largest moons, the ones first seen by Galileo in 1610.

Modern day space probes and telescopes can see the Galilean moons in full color. The image caption on the photo below explains: From left to right in order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto.

Timelapse photography allows us to see the Galilean moons orbiting Jupiter as NASA’s Juno spacecraft approaches. These are only four of the 80 known satellites of Jupiter, most of which are less than 10km (6.2 miles) in diameter. 80 moons!

Moons Io and Europa have sparked a lot of interest.

• Io has more than 400 active volcanoes as well as splendid dunes that were documented last April.
• Europa is icy with water underneath, hence one of most promising places in the solar system to look for extraterrestrial life.

And finally, Thursday is a good day to feel jovial. According to Wikipedia, the older adjectival form jovial, employed by astrologers in the Middle Ages, has come to mean “happy” or “merry”, moods ascribed to Jupiter’s astrological influence.

Happy Thursday!

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

8 October 2022

Sunrise and sunset have been very colorful in Pittsburgh lately.

On 6 October the sky was clear with some thin clouds and airplane contrails. The rising sun lit the contrails a hot pink-red. Detail photo above, wide-angle below.

On 30 September the sunset was fiery.

Every day is shorter as sunrise and sunset get closer to each other. By 18 October we will have an hour less of daylight than at the Equinox.

p.s. Unfortunately the sunrise on 6 October many have been colorful because the air was so bad. Everyone in the Mon Valley could smell it. Hydrogen sulfide exceeded the 1-hour limit at the Liberty-Clairton monitor, an exceedance which “can be attributed entirely to emissions from US Steel’s Clairton coking facility.” Read more at GASP-pgh.org

(photos by Kate St. John)