Sunrise on the summer solstice, Pittsburgh, 21 June 2023 (photo by Kate St. John)
Wednesday 21 June 2023
Two days ago we learned how humans are changing the tilt of the Earth(*). Today we celebrate the most important Tilted Earth Day in the northern hemisphere when the summer solstice occurs at 10:57am EDT and gives us the longest day.
Three years ago meteorologist Bill Kelly made this video at WJLA in Washington, DC explaining how the Earth’s tilt is the key to the solstice. Only one fact has changed: The solstice is on a different date and time. Sunrise, sunset, and day length are the same in DC today as they were on the solstice in 2020.
In Pittsburgh today the sun rose at 5:49am, we’ll have 15 hours, 3 minutes and 50 seconds of daylight, and the sun will set at 8:53pm. Thanks to the tilted Earth.
(*) p.s. How much have humans changed the tilt of the Earth? The study highlighted in Monday’s blog calculated that we’ve already moved it 80 cm (31.5?) in just 17 years (1993-2010). Click here to read more.
(photo and video credits: Click on the captions to see the originals)
Occasionally during the May-to-August storm season, the National Weather Service warns of flash flooding because of potential “training thunderstorms.”
Training thunderstorms? Are they getting in shape for a big competition? Are they practicing to be better thunderstorms? Are they learning from older, wiser storms?
No. “Training” in this case means the storms are lined up in a row, moving one after the other like railcars in a train. The Philadelphia Area Weather Book describes it:
Most of the year, thunderstorms, steered by speedy winds a few miles above the ground, move along quickly enough so that flooding is not a problem. But those high-altitude winds are typically much weaker in summer and, at times, nearly calm. When this happens, thunderstorms can sit over the same spot for hours. Even if the steering winds are not that lazy, flooding can still occur if the winds blow parallel to a line of storms. When that happens, one thunderstorm after another passes over the same location like railroad cars in a train passing over a track. Appropriately meteorologists call this process training.
When radar-watching meteorologists saw this phenomenon they turned the concept of “moving like a train” into an adjective describing thunderstorm behavior. The new use of an old word did not catch on. Though it’s been around at least 30 years it’s not in the dictionary.
Compared to the size of our planet we humans aren’t particularly large but with billions of us pumping groundwater we have changed the tilt of the Earth. Slightly.
The angle of Earth’s axial tilt varies over a period of 26,000 years (precession) from 22.1 to 24.5 degrees, but within that it wobbles due to sloshing liquids like molten lava, ocean currents, and massive air currents such as hurricanes.
This very short video shows the North Pole wandering as the axis wobbles.
Earth’s spin axis wobbles, its North Pole tracing out a roughly 10-meter-wide circle every year or so. The center of this wobble also drifts over the long term; lately, it has been tilting in the direction of Iceland by about 9 centimeters per year. …
Now, scientists have found that a significant amount of the polar drift results from human activity: pumping groundwater for drinking and irrigation.
To find out what affected Earth’s axial tilt, Clark R. Wilson at the University of Texas at Austin and his colleagues built a model of polar wander factoring in all the sloshing over time, including changes to surface water. But the model was missing something.
When the researchers also put in 2150 gigatons of groundwater that hydrologic models estimate were pumped between 1993 and 2010, the predicted polar motion aligned much more closely with observations. Wilson and his colleagues conclude that the redistribution of that water weight to the world’s oceans has caused Earth’s poles to shift nearly 80 centimeters during that time, reported Thursday in Geophysical Research Letters.
The GRACE satellites detected groundwater changes that produced this map. Notice how groundwater dropped in the U.S. Southeast and the Central Valley of California.
Goatsbeard gone to seed, SGL 117, 6 June 2023 (photo by Kate St. John)
10 June 2023
Goatsbeard (Tragopogon dubius) lived up to its name this week as it showed off its huge fluffy seed head at SGL 117 in Washington County, PA.
Nymphal froghoppers known as spittlebugs hid under foam while sucking plant juice at Frick Park.
Spittlebugs, Frick Park, 8 June 2023 (photo by Kate St. John)
A fluffy white substance that looked like fungus may well be insects — perhaps woolly aphids (“boogie woogie” aphids) sipping sap from a cut branch.
Are these aphids
Canadian wildfire smoke made for eerie an sunrise on Thursday morning. My photos of it were anemic. Check out Dave DiCello’s instead. Click on a photo to enlarge it.
'The blood moon rises once again…'
Not really. But the sun looked eerie as it rose behind the smoke from the Canadian wildfires today in #Pittsburgh. The smoke and haze are supposed to get worse as the day goes on, so stay safe out there. So weird to see the city like this. pic.twitter.com/nZKJEg6R1f
White snakeroot (Ageratina altissima) wilting in Schenley Park, 7 June 2023 (photo by Kate St. John)
9 June 2023
Plants are drooping, water levels are low, and clouds of dust engulf dirt roads in western Pennsylvania. It hasn’t rained for almost three weeks at a time of year that’s usually wet. Yesterday it became official. We’re in a drought.
Every week the U.S. Drought Monitor at University of Nebraska-Lincoln issues a nationwide drought assessment. Pennsylvania is labeled “SL” on this week’s map for evidence in both Short term and Long term indicators. (Click here for the latest Drought Map.)
The drought seems sudden but it’s been building for a while. Precipitation was above normal last year through January 2023 but starting in February it fell off. April and May were seriously below normal. June has been bone dry so far. As of today Pittsburgh has a year-to-date precipitation deficit of 4.55 inches.
Sunset in Pittsburgh 3 June 2023. Pink sun due to Canada’s wildfire smoke (photo by Jonathan Nadle)
6 June 2023
On Saturday evening Jonathan Nadle took a photo of the setting sun glowing pink with threads of smoke across its face. The color was the result of wildfire smoke drifting in from western Canada.
Today Pittsburgh and much of the northeastern U.S. are under an air quality alert because the smoke is now at ground level. We don’t see it as smoke — it looks like haze — but the particles have put our air quality forecast into Code Orange = “Unhealthy for Sensitive Groups.” Young children, seniors, and those with respiratory problems should limit outdoor activities.
Millions of people across the Midwest are under dangerous air quality conditions Monday, as smoke from wildfires in eastern Canada wafts over the region.
Hazy skies have blanketed a wide swath of the country from the Ohio Valley to as far south as the Carolinas. Air quality advisories are in effect Monday in southeastern Minnesota and parts of the Upper Peninsula of Michigan, as well as in more than 60 counties in Wisconsin.
The spike in air pollution comes from wildfires that have been raging in the Canadian provinces of Quebec and Nova Scotia.
… Canada is experiencing one of the worst starts to its wildfire season ever recorded.
There are wildfires across much of Canada right now — west and east — but the fires affecting Pittsburgh today are mostly in Quebec and nearly all are out of control, displayed as red dots on Canada’s interactive wildfire map. Click here or on the screenshot below to see the interactive map.
For Pittsburgh the smoke is mostly an inconvenience but for Canadians it is dangerous and for the birds that nest in these forests it is deadly. The fires are happening where northern warblers breed including bay-breasted, blackpoll, palm, Cape May and Tennessee.
When we see fewer of these migrating warblers in the fall, the fires will be partly to blame.
7 June 2023, 5:00am: The winds have changed. Pittsburgh air is still Unhealthy for Sensitive Groups this morning but it is much worse elsewhere. It is Very Unhealthy from Harrisburg to Philadelphia (purple), and Hazardous to breathe in a wide swath of Ontario including Ottawa (brown).
From Earth, Saturn is tiny and the Moon is large. You can see the huge size difference in Paul Byrne’s (@ThePlanetaryGuy) video of Saturn rising behind the Moon.
Every once in a while, if you time it just right, you can see Saturn rise from behind the Moon. pic.twitter.com/gnRAVQSgyu
This morning’s weather forecast includes an unusual warning. There’s a Fire Weather Watch in Pittsburgh today from 11am to 8pm. The relative humidity is low (25-30%), the winds will be gusty (up to 25 mph) and it’ll be hot (almost 80ºF!).
Spring is fire season in Pennsylvania when 85% of our wildfires occur. As the growing season begins, forests and fields are covered in dry leaves and grasses. Under the right weather conditions a cigarette tossed from a car or a trash burn will catch and spread quickly.
That’s probably how this distant wildfire started in Fayette County in March 2011 (photo by Jon Dawson).
(photos from PA National Guard and Jon Dawson on Flickr via Creative Commons license, weather forecast screenshot from NWS, Fire Danger Map from PA DCNR)
Star magnolia in bloom, Schenley Park, 27 March 2023 (photo by Kate St. John)
1 April 2023
Welcome to April! Last month brought flowering trees, frost damage, more flowers and early leaf out.
The star magnolia (Magnolia stellata) above was looking good on 27 March but the one below bloomed too early on Pitt’s campus and sustained frost damage.
Frost damage on a star magnolia, Univ of Pittsburgh campus, 22 March 2023 (photo by Kate St. John)
This honeybee didn’t care about the brown petals. She probably flew in from The Porch beehives across the street.
Honeybee at frost-damaged star magnolia, Univ of Pittsburgh, 22 March 2023 (photo by Kate St. John)
Non-native flowers are blooming. Eyebright (Euphrasia sp) popped up in the grass at Frick.
Eyebright in Frick Park, 22 March 2023 (photo by Kate St. John)
Purple dead-nettle (Lamium purpureum) bloomed before the frost and still looked good on the 29th, here with chickweed (Stellaria media) in a Shadyside front yard.
Purple dead-nettle and chickweed, 29 March 2023 (photo by Kate St. John)
Meanwhile leafout is already underway. Bush honeysuckle had leaves on 18 March.
Bush honeysuckle leafout in Schenley Park, 18 March 2023 (photo by Kate St. John)
Tomorrow the Spring Equinox will occur at 5:24pm EDT. Some will mark the day by visiting a celestial calendar, a structure where sunrise lines up with particular stones. At Angor Wat, below, the sun rises behind the middle tower.
Tonight the Hike Inn is probably full to capacity with all 20 bunkrooms in use. Tomorrow everyone will be up and out before dawn to watch the sun rise.
The most famous aspect of the Hike Inn is not the Star Base but the fact that you have to hike 5 miles to get to it. No vehicle access. Check-in at the Amicalola Falls State Park Visitors Center, park your car at the trailhead and start your hike. The Appalachian Trail’s southern terminus at Springer Mountain is (relatively) nearby.
Upon arrival put your phone in airplane mode. The Hike Inn is intentionally unplugged, though they do have electricity (mostly solar). No TV, no radio, no phone … just enjoy the quiet time.
