Now matter where you are on Tuesday December 22 at 4:48 am UTC — in Calcutta, India (above) or the frozen Yukon — you’ll experience the northern solstice.   (NOTE that December 22, 4:48am is Universal Time!  In Pittsburgh the solstice is at 11:48pm on Monday December 21.)

Here at latitude 40^o North we think the solstice is a northern daylight event but it’s actually an astronomical event that happens everywhere on Earth at the same moment.  At the North Pole there’s nothing to see; it’s been dark for a long time.  In Australia they’re having their longest summer day.

In Pittsburgh we reached our shortest number of (rounded) minutes on December 17 — 9 hours and 17 minutes — and we’ll stay there, gaining only seconds per day, until December 26.  Then on the last day of the year we’ll begin to gain a minute a day.  At last!

Here’s good news for people with Seasonal Affective Disorder (SAD):  We’re going to turn the corner soon.

(photo by Biswarup Ganguly via Wikimedia Commons. Click on the image to see the original)

Ever since May’s dry weather, Marianne Atkinson and I have kept up a lively email conversation about drought and rain in our respective hometowns, Dubois and Pittsburgh.

Dubois has been short-changed on rainfall this year despite June’s excessive wet weather.  Most months have been so dry that June’s 3.36″ above normal could not overcome the drought.

Even their “good” rainfall statistics are misleading because most of it falls in a single heavy downpour event.  As of today, Dubois received 1.3 inches of rain in August but 98% of it fell in one 24 hour period — August 10-11.

We shouldn’t be surprised.  Climatologists predict that as the climate heats up western Pennsylvania’s weather will change from gentle rains to frequent heavy downpours.

Meanwhile Marianne watches the weather radar closely.  When rain is predicted will her garden get any of it?  No. As the storm clouds approach they usually part north and south, missing Dubois completely.  She sent me this screenshot of a recent “rainy” day from Accuweather.

I’ve seen this phenomenon, too.  On Monday night Pittsburgh got a trace while Youngstown and West Virginia were slammed.

Is your town suffering from localized drought?  Have you noticed this parting-of-the-clouds phenomenon?

It reminds me of Arizona’s monsoon.

(photo by Kate St. John)

Throw Back Thursday (TBT):

If you’ve seen me outdoors when a thunderstorm’s approaching you know that I take lightning safety so seriously that I go inside before everyone else.  I like to think it’s because I know too much.

Some of that knowledge was collected in 2011 when I researched the facts for this article on Lightning.  Once you start looking there are plenty of harrowing stories.

U.S. lightning safety has changed since 2011.  Back then I wrote about the Lightning Crouch but it’s been discredited unless you’re stuck outdoors very far from shelter.  The new motto says run for shelter: When Thunder Roars, Go Indoors.

Yet I wonder … is my level of concern about lightning borne out by statistics?  It depends on what’s about to hit you.  Here are some death/injury facts from 2012 when the U.S. population was 314,100,000 (314.1 million puts the numbers in perspective).

Clearly lightning is much less likely to kill you than a motor vehicle.  On the other hand, there are far more vehicles than there are lightning bolts and far more hours spent in vehicles than outdoors during storms.

So drive safely, don’t drink and drive (alcohol accounts for 1/3 of the deaths), look both ways when you cross the street, and … when thunder roars I’m still going indoors.

(Thunderhead with lightning, photo by jcpjr from Shutterstock)

p.s. I’ve included trains in the list because Westinghouse Bridge peregrine fans are no longer allowed near the railroad tracks.  Trains are the most deadly of all the dangers.

The ground was parched and cracked in my backyard yesterday morning, so I looked forward to the thunderstorms predicted in the afternoon.

It rained north and west of here but only a trace in my backyard and at Pittsburgh International Airport.

The real rain missed us again.

(image composite from the National Weather Service /FAA)

21 March 2015

The word Analemma sounds like a girl’s name or perhaps an exotic fruit but in fact it’s the name for that figure 8 hanging in the sky above.  You won’t see it in Nature but you may have seen it as a symbol printed on an old-fashioned globe of the world.

Technically speaking an analemma is the location of one celestial body as viewed from another for one complete orbit.  Practically speaking it’s the Sun’s position throughout the year at the same location and time of day on Earth.   I was surprised to learn it’s a figure 8 but that’s because the Earth’s orbit is elliptical and tilted.

This photo took a whole year to create.  Every other week in 1998-1999, Jack Fishburn took a photograph of the sun’s position from his office window at Bell Labs.  He was careful to place the camera in the exact same position and snap the photo at the same time of day (correcting back to Standard Time during Daylight Savings).  After collecting a year of photographs he overlaid them to create the analemma.

Tunc Tezel did the same thing at Baku, Azerbaijan and made it a movie here.

You can create your own analemma if you’re persistent (one whole year) and precise (same camera location and time of day for every photo) and have access to Photoshop.

When you’re done you’ll know that the top of the 8 is the summer (northern) solstice, the bottom is the winter (southern) solstice, and the crossover point is both equinoxes.  Today, one day after the Northern Equinox, the sun is very near the center of the analemma.

(photo by Jack Fishburn via Wikipedia GNU Free License. Click on the image to see the original)