Category Archives: Weather & Sky

Get Ready For The Solar Eclipse, Aug 21

Map of the Total Solar Eclipse on 21 August 2017 (image from NASA)
Map of the Total Solar Eclipse on 21 August 2017 (image from

By now I'm sure you've heard ...

Two weeks from today on 21 August 2017 there will be a total eclipse of the sun across the United States.  The moon will pass between Earth and Sun, casting its shadow on our continent.

In a narrow band 70 miles wide, from Oregon to South Carolina, the sun will disappear completely for about two minutes. Folks eager to witness the total eclipse have made plans to visit sites in its path including Nashville, TN and Charleston, SC.

Pittsburgh will see only a partial eclipse but there will be plenty to watch. The moon will move across the sun from 1:10p to 3:55p with maximum coverage resembling the crescent below at 2:35p.  Don't watch without special glasses and, for your scope and camera, special filters!  See below.

Mockup of partial eclipse at maximum as it will be seen in Pittsburgh on21 Aug 2017 (image from Wikimedia Commons)
Mockup of partial eclipse at maximum as it will be seen in Pittsburgh on 21 Aug 2017 (image from Wikimedia Commons)

Where to watch the eclipse in Pittsburgh, 21 August 2017 ... some of the many locations.

  • On your computer: See the entire eclipse from coast to coast on NASA's Eclipse Live Stream. The shadow begins in Oregon at 9:04a PDT (12:04p in Pittsburgh) with totality from 10:16a PDT (1:16p here) to 2:48p in South Carolina.  You don't need filters to watch online.
  • At Carnegie Science Center: The weather won't matter at Carnegie Science Center. Outdoors, watch through special solar observation equipment.  Indoors at Buhl Planetarium. Click here for info & directions.
  • Sidewalk Astronomy: Weather permitting 1:30p to 3:00p outside the Staghorn Garden Cafe, 517 Greenfield Avenue, Pittsburgh, 15207.   John English will set up his scope to project the sun's image on the wall so you can watch its shadow without looking at it.
  • In your own backyard:  Prepare in advance! Read Eclipse2017: Who, What, Where, When and How and get ...

Special solar eclipse glasses, filters or pinhole viewers to watch the solar eclipse.

Don't risk going blind or damaging your camera or scope by viewing the eclipse without protection! Click here for NASA's list of safe viewing methods including solar eclipse glasses, pinhole viewers and filters for your equipment + how to use them.

Solar eclipse glasses are inexpensive (only a couple of dollars) at the Carnegie Science Center Gift Shop or online but only buy from reputable vendors listed at American Astronomy Society! Sunglasses and fake glasses won't protect you.

Here's an example of the real thing from B&H Photo Video on the reputable vendor list.

Lunt solar eclipse viewing glasses from B&H Photo
Lunt solar eclipse viewing glasses from B&H Photo

I hope it isn't cloudy on Monday August 21!


(photo credits: Click on the images to see the originals. Globe from Partial eclipse image from Wikimedia Commons. Lunt solar eclipse glasses from B&H Photo Video)

Gulf Tower Fledge Watch: The Forecast


It doesn't look good for Gulf Tower Fledge Watch this weekend.  As of this writing I have altered the schedule.

Today, Friday May 26:  yes, I'll make the attempt AFTER NOON.  See you downtown at 1100 Liberty Avenue after the rain stops.  (It's pouring now.)  Click here for directions.

Saturday May 27:  no

Rain and thunder forecast, May 26-27, Pittsburgh (mage from
Pittsburgh rain and thunder forecast, 26-27 May 2017 (image as of 26 May from with relevant times framed in orange)


Sunday, May 28: yes.  The forecast has changed for the better. See you at Flag Plaza.

Monday, May 29, Memorial Day: yes. See you at Flag Plaza.



(screenshots of the Hourly Weather Forecast for Pittsburgh, PA from as of 8am 26 May 2017)

Fewer Mild Weather Days

Mild weather during the Cherry Blossom Festival in D.C., 2006 (photo by Andrew Bossi via Wikimedia Commons)
Mild weather during the Cherry Blossom Festival in Washington, D.C., 2006 (photo by Andrew Bossi via Wikimedia Commons)

Ah, the mild days of spring!  You know the days I'm talking about, the ones that are perfect for birding, gardening, picnics and outdoor weddings.  The not-too-hot, not-too-cold, not-too-wet weather that makes you happy to be outdoors.

Unfortunately Pittsburgh will have fewer of them in the future. That's what scientists from NOAA and Princeton University found out when they studied how the warming climate will affect our pleasant weather.

The loss has begun already though you may not have noticed it. For the last 35 years (1980-2015) earth's climate has been converting 1 nice day per year into something unpleasant, mostly in Brazil, Africa and the Middle East.

By the end of the century the change will affect us.  The world will lose 10 mild days out of 74 but the loss won't be evenly distributed.  The tropics will lose even more mild days while Canada, Maine and the Rockies can look forward to a pleasant future.

Here's what our future looks like on the map.  Notice how the eastern U.S. is light orange indicating a net loss.

Change in Number of Mild Weather Days by 2090 (map from Van der Wiel/ NOAA/ Princeton)
Map showing the change in the annual number of mild days across the globe comparing 1986-2005 to 2081-2100. Areas of blue have increased in mild days. Areas of brown see a decline. (Van der Wiel/ NOAA/ Princeton)

That map shows the annual change but in fact it will vary by season.  For instance, Pittsburgh will gain some mild days in the fall (maybe 15) but lose more than that in the summer (25 to 50).  June-to-August will be hot!

Changes in the number of mild weather days by season by 2090 (map from Van der Wiel/ NOAA/ Princeton)
Changes in the number of mild weather days by season for 2090 (maps from Van der Wiel/ NOAA/ Princeton)

The full report includes details on mild weather in major cities at: Shifting patterns of mild weather in response to projected radiative forcing.

Now, more than ever, mild weather is a gift.  Enjoy it while you can.


(photo by Andrew Bossi via Wikimedia Commons; click on the image to see the original.
Climate map screenshots from Shifting patterns of mild weather in response to projected radiative forcing

(*) "Mild weather" is defined as temperatures between 64 and 86 °F, only a trace of rain (less than 0.04 inches) and low humidity (a dewpoint below 68 °F).

I’m Moving Northward

Carolina chickadee in North carolina (photo from Wikimedia Commons)
Carolina chickadee in North Carolina (photo from Wikimedia Commons)

Last week I wrote about Pittsburgh's Puzzling Chickadees and promised to tell you why we have fewer black-capped chickadees every year.  The reason is: Our winters are getting warmer.

The Pittsburgh area is squarely in the contact zone where black-capped (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis) meet and hybridize.  Black-capped chickadees can survive cold winters so they live north of the zone.  Carolinas cannot; they live in the south.

The contact zone snakes from New Jersey to Kansas, dipping south along the chilly Appalachian Mountains.  Studies by Robert Curry and his team at Villanova University found that the contact zone is located where winter low temperatures average at or above 14 to 20oF.

In 2010 David Sibley drew the contact zone for his Distinguishing Black-capped and Carolina Chickadees article. Click on the screenshot to see his original map and zoom it for your area.  The map is about 7 years old.

Screenshot of David Sibley's map of the black-capped and Carolina chickadee contact zone in 2010 (click on the map to see the original and zoom it in for your area)
Screenshot of David Sibley's map of black-capped and Carolina chickadee contact zone approximately 2010. Click on the map to see Sibley's original article and zoom the map for your area.


Seven years make a difference.  During that time the zone moved north almost 5 miles.  Here's why:

Chickadees don't migrate but young birds disperse to find a breeding territory.  The easiest territory to claim is an "empty" place where there aren't competing birds of the same species.  For Carolina chickadees, that place is on the northern edge of the contact zone.

In 2000-2002 and 2010-2012, Robert Curry and his team measured winter temperatures and conducted DNA tests to identify chickadees in study plots north, south and inside eastern Pennsylvania's contact zone.

The studies showed that over the 10-year period winter average low temperatures moved north 0.7 miles per year. They also found that female Carolina chickadees are dispersing further than their usual 0.6 miles.  They're moving 0.7 miles northward in lock-step with climate change.

What does this mean for you?

If you live on the northern edge of the contact zone your chickadees can change in a year or two from 100% black-capped chickadees to a mix including Carolinas and hybrids.  On the southern edge it's just as interesting as the black-cappeds disappear.

So don't take Pittsburgh's chickadees for granted.  The contact zone is moving northward.


(photo from Wikimedia Commons, map screenshot from David Sibley's blog: Distinguishing Black-capped and Carolina Chickadees.  Click on each image to see the original.)


Winter sunset at Kuznetsk Alatau, South Siberia (photo from Wikimedia Commons)
Winter sunset at Kuznetsk Alatau, South Siberia (photo from Wikimedia Commons)

By the time you read this, the winter solstice will have passed.

The sun paused it's southward journey today at 5:44 AM Eastern Time and is already moving north.

Soon the days will be getting longer and the birds will begin to sing.

Listen for the song sparrow.  What day will he sing his first song?


(photo from Wikimedia Commons. click on the image to see the original)

Variably Icy

Icy path in Schenley Park, Feb 2015 (photo by Kate St. John)
Icy trail in Schenley Park, Feb 2015 (photo by Kate St. John)

Snow, sleet, rain, freezing rain.

From 5 degrees F on Thursday night to 53 degrees with freezing rain today, we've had it all.  And there's more to come.  Tomorrow night will be 15 degrees.

This yo-yo weather reminds me of what we learned during the polar vortex in January 2014:  Climate change is making the jet stream wobble so we get shots of very cold air and then warm air soon after, as shown in drawing(c) below.

Jet stream Rossby waves (graphic from Wikimedia Commons)
Jet stream Rossby waves (graphic from Wikimedia Commons)


Be careful today!  It's variably icy out there.


p.s. I've used an old photo of ice because it's too icy to step outside this morning!

(photo by Kate St. John.  Drawing from Wikimedia Commons; click on the image to see the original)

Uh Oh! Blue Light Isn’t Better


Uh oh!  Blue light, though bright, isn't better at night.

As cities switch from incandescent or mercury street lights to LEDs they're saving electricity and money and providing more light.  But brighter isn't better if it's blue.

The video above shows how the color temperature of light matters to our eyes and sleep patterns.  Though the video doesn't mention it, the color also matters to birds and animals.

It's possible to buy yellow-toned LEDs but blue, because its bright, has been the default choice for city lights.  We didn't know that color mattered when the world began switching to LEDs and the bulbs have such a long life it'll be decades before it's time to replace them.  Meanwhile humans, birds and animals will be coping with the change.

It makes me want to close my eyes.


(video by TOMO news on YouTube)

p.s. Here's a really helpful video showing the difference between incandescent, compact fluorescent and LED light bulbs in home use (the A19 screw base).  You'll also see the inside of an LED bulb. I was surprised to learn it's a tiny computer.

How We’ll See The Stars Again

In my blog two weeks ago, the night sky video Lost in Light made me wonder how we'll ever see the stars again.

Since then I've learned that our outdoor lights waste money and energy, disrupt wildlife, and ruin our own sleep patterns.  What we can do?

The video above from McDonald Observatory shows a simple answer.  Use lampshades.

The quick demonstration below shows why.


Right now our cities and towns are switching out incandescent street lights for LEDs.  It's the perfect time to put on lampshades.    You can shade your home lights, too.


p.s. Stay tuned for a future blog about blue light versus red spectrum LEDs.  Yes, the color matters.

(videos from McDonald Observatory and

We Cannot See The Stars


Have you ever seen the Milky Way?

That question would have been absurd 200 years ago because billions of stars were visible on every clear night.

But now with the prevalence of artificial outdoor light most of us cannot see the Milky Way and many children don't know what it is.

Because of this, some ancient stories don't make sense.  In Genesis Abraham worried that he had no heir but God reassured him, "Look up into the sky and count the stars if you can. So many shall your descendants be."   Today we look at the sky and count 50 stars, not realizing that Abraham was overwhelmed.

So what are we missing?  Sriram Murali traveled in California recording time-lapse video of the night sky in places with high light pollution (San Jose) and almost no artificial light (Death Valley).

His video let's us see the sky as our ancestors did.

Watch the stars come out.


(video by Sriram Murali)