Category: weather

Can the groundhog see his shadow?

February 6, 2026 • 11:45 am

The old Groundhog Day trope is this, “As the tradition goes, if the groundhog sees his shadow, we will have six more weeks of winter. If he doesn’t, an early spring is coming.”  The holiday is celebrated on February 2, and over the years the tradition has come to center on Punxsutawney Phil, a groundhog who lives in the eponymous Pennsylvania town.

Every year on February 2, a group of top-hatted men called the “Inner Circle” haul the hapless rodent out of his hibernation, slap him down on a lectern like a pancake, tap him with a cane, and then wait a bit. Then they lift the groundhog into the air and proclaim, via a poem, whether or not he saw his shadow. Here’s this year’s prediction: Phil did see his shadow (so they surmised) so we’re in for a long winter:

Of course the exercise is ludicrous, and Phil’s record of predictions is abysmal: about a 35%-40% accuracy.  But I can prove from first principles that this exercise is futile from the get-go.

Here:

To determine if the groundhog sees his shadow there must be

1.)  The possibility of a shadow (i.e., the sun must be shining), and

2.) If there is a shadow, the groundhog must have the ability to see it, and we have to know if he did or did not.

But if there is no shadow, as when the weather is overcast like this year, then the groundhog has nothing to see or not see, so he clearly cannot see his shadow whether or not he looks.  Thus, if the weather is overcast (as it was this year), you don’t need a damn groundhog: there will be an early spring. (As you see above, he is said to have seen his shadow! Oy!)

If there IS a shadow, then you have to determine whether the groundhog saw it.  I doubt that we’re able to do this, as Punxsutawney Phil is not trained to indicate whether or not he saw his own shadow. Thus if it’s sunny, the prediction becomes indeterminate.

Therefore there is only one possible predictive outcome, and that depends solely on whether the weather is sunny or not. The sole prediction is this (here it comes): no shadows possible, therefore an early Spring. That is, of course, bogus as well.

You could diagram this with a decision tree, but I think my logic here is impeccable given our inability to detect qualia in groundhogs. And this indicates why Phil’s bogus “predictions”, based on what the top-hatted men say, have been so inaccurate.

Punxsutawney Phil sees his shadow

February 2, 2026 • 9:00 am

Over in Punxsutawney, Pennsylvania, they dragged out a groggy groundhog (Marmota monax), Punxsutawney Phil, from his wooden-box den, and determined whether he could see his shadow.

He did, and that means that we have six more weeks of winter weather to come.  Is that any surprise?

Below is a short video in which Phil is forced to look at a piece of paper. Who knows if he actually saw his shadown, but the top-hatted flacks, members of the so-called “Inner Circle” who interpret Phil’s predictions, did.

But looking at Phil’s history, the rodent is not accurate at predicting the long-term weather:

The Inner Circle claims a 100% accuracy rate, and an approximately 80% accuracy rate in recorded predictions. If a prediction is wrong, they claim that the person in charge of translating the message must have made a mistake in their interpretation. Empirical estimates place the groundhog’s accuracy between 35% and 41%.

So it goes.  It’s a groundhog, for crying out loud, not a weatherman. And the Inner Circle is a religion. . . .

 

Readers’ wildlife photos

January 1, 2026 • 8:15 am

We start the new year with clouds, which, though some say they’re loaded with bacteria (and created by the bacteria as a means of dispersal), we’ll consider nonliving atmospheric phenomena.  This montage could be called, “I’ve looked at clouds that way,” and comes from reader David Jorling in Oregon.  David’s captions are indented, and the photos can be enlarged by clicking on them.

First of all here is an overly simple chart that I used to identify the clouds:
UCAR/L.S. Gardiner

 

As to these three photos, the first was taken at Mary S Young State Park while I was walking my dog.  These are “cirrus” clouds which, as I understand it, means there are strong winds in the upper atmosphere:

As to the following two pictures, which were taken from my yard amongs the Douglas Fir Trees.  My best guess (and perhaps one of your readers has more expertise is that these are a mixture of cirrostratus and cirrocumulus clouds.  perhaps in a state of transition:

More pictures taken from my yard. Again my best guess as is cirrrostratus clouds:

Perhaps these are in transition from cirrostratus to cirrus:

My suspicious is that these are Cirrostratus transitioning to cirrus:

This one was taken at sunset near Timberline Lodge on Mt Hood. They may have appeared lower perhaps because I was at about 6000 feet elevation instead of about 300 feet where I live. So my suspicion is that these are either cirrocumulus or altocumulus clouds:

This is a picture from my yard toward some neighboring Douglas Firs and assorted evergreens.  I suspect these are cirrocumulus clouds:

 

This is a picture I took from my car during a nationally forecast “Atmospheric River”. (In Oregon we call it “Rain”.) The picture was taken westbound on the Ross Island Bridge.  The building above the Stratocumulus cloud (in Oregon we call it a “Fog Bank”) is one of the buildings of the Oregon Health Sciences University, which is the main medical school in Oregon:

It’s snowing again! (and a quiz)

December 7, 2025 • 6:30 am

Well, winter is still two weeks away, but tell that to the clouds.  Last night it snowed several inches in Chicago—and it’s still coming down. The streets seem impassable, putting the kibosh on my plans to do grocery shopping today, and I’m out of the essentials at work, including peanut butter and tuna.

But it’s still lovely. Here, for example, is Botany Pond. I hope the turtles are hibernating safely despite the pond’s gravel bottom.

My tracks on the way to work. Could you identify these as human tracks? It looks as if I was weaving drunkenly, but I was just avoiding certain spots.

But here are tracks of another creature. The quiz is, WHAT MADE THESE TRACKS?  Answer at 11 a.m. Chicago time.  Please don’t put your answers in the comments, but if you think you know, do say that.

And you’re lucky if you can get to the grocery store!

Big snow!

November 29, 2025 • 2:12 pm

They predicted this storm, and pretty accurately, too. The weather report last night said that it would fall lightly starting at 3 a.m., and would turn heavier in the afternoon, accumulating to between 8 and 12 inches. And that is what happened, though the accumulation is less than six inches at the moment while it continues to snow heavily.

Here is the snow falling around Botany Pond.  There should be five big turtles huddled in their houses at the bottom of the pond.

And snow in the quad. It will be over by the evening, we are told, and I will not have to get my head covered with the white stuff as I walk to work.

 

Readers’ wildlife photos

November 20, 2025 • 8:15 am

We have two batches left and this is one of them (i.e., send in your photos). Today we have some photos of the Aurora Borealis (and a few other things) taken by Ephraim Heller:

I was fortunate to be in Alaska on the night of Nov. 11-12 when the aurora borealis put on the best show of the year, widely visible across North America. I photographed the event at Birch Lake, about 50 miles southeast of Fairbanks.  I shot the aurora from 10pm – 3am as the temperature registered -16° F (-27° C) and I coughed with a cold. It was worth it.

“Aurora borealis” is Latin for “northern dawn.” Despite my wasted BA in Physics, I have never understood what causes the aurora. I decided to look it up and share what I learn with readers of WEIT. Real physicists and astronomers should feel free to correct my errors. Thanks to NASA and to Akari Photo Tours for nice explanations on their websites, from which I have borrowed liberally.

Our sun continuously emits a stream of charged particles (the solar wind) which flows outward through the solar system. When this plasma reaches Earth, it interacts with our planet’s magnetic field (the magnetosphere), depositing and accumulating energy there. During a geomagnetic storm, much of the accumulated energy in the magnetosphere flows down along Earth’s magnetic field lines. As these accelerated particles descend into the atmosphere they collide with oxygen and nitrogen molecules at altitudes between 100 and 300 kilometers. These collisions excite the atmospheric gases, causing them to emit photons.

The detailed version: coronal mass ejections (CMEs) are the eruptions of plasma and magnetic field from the Sun’s atmosphere that drive the most intense geomagnetic storms. If directed at Earth, fast-moving CMEs can reach our planet in as little as 15 hours traveling at ~6.2 million mph (10 million kph).

The critical process triggering auroras is called magnetic reconnection. The solar wind flows around Earth’s magnetosphere like a river rushing around a rock. This onrush of charged particles stretches Earth’s magnetosphere away from the Sun, creating a long wake known as the magnetotail. The magnetic shields of the Sun and Earth are polarized. The polarity of Earth’s magnetic shield is mostly stable, but the Sun’s can vary rapidly. When the polarity of the solar wind is opposite that of Earth’s magnetosphere, the field lines of the Sun and Earth interact strongly. The solar wind then pushes these connected field lines around Earth’s magnetosphere. Eventually, these field lines reach their limit and snap back, releasing energy. This energy accelerates charged particles – primarily electrons and protons – along Earth’s magnetic field lines toward the polar regions, injecting millions of amps into the atmosphere.

Oxygen excited to different energy levels can produce green and red. Green occurs roughly between 60 to 120 miles (100-200 km) altitude, and red occurs above 120 miles (200 km). Excited nitrogen gas from about 60 to 120 miles (100-200 km) glows blue. Depending on the type and energy of the particle it is interacting with, nitrogen can give off both pink and blue light. If it is below about 60 miles (100 km), it gives the lower edge of the aurora a reddish-purple to pink glow.

Aurora brightness depends on (i) the intensity of solar activity and (ii) the efficiency of energy coupling into Earth’s magnetosphere. The standard measurement for the intensity is the Kp index, which ranges from 0 to 9, derived from 13 magnetometer stations globally that monitor Earth’s magnetic field disturbances. A Kp index of 0 represents quiet conditions; a Kp of 9 represents an extreme geomagnetic storm capable of producing auroras near the equator.

Unfortunately, the Kp index has a serious limitation: it reports a 3-hour global average so it is often too slow and too generalized to capture short-lived auroral activity, such as auroral substorms (which typically last 10 – 30 minutes). These powerful bursts can produce the brightest northern lights displays, yet they are frequently missed when relying only on KP forecasts.

Aurora intensity also depends critically on the interplanetary magnetic field’s Bz component. When the solar wind’s magnetic field points southward (negative Bz), conditions favor magnetic reconnection and enhanced energy coupling, producing increased aurora activity. When it points northward (positive Bz), reconnection is suppressed, resulting in reduced activity. Bz values below -10 nT are considered effective for driving geomagnetic storms, and values in the range of -20 to -30 nT usually indicate strong conditions for auroral activity.

Unfortunately, there is no way to predict the Bz. So even when the Kp is high there will be no aurora if the Bz is positive… and you just won’t know until you’re standing next to a lake outside of Fairbanks in -16° F weather with a respiratory infection.

So what happened on the night of November 11-12? Two coronal mass ejections reached earth, the Kp spiked to 8.67 (almost at the maximum value of 9), while the Bz reached a remarkable nadir of -55 nT!

Finally, I have been asked why photographs of auroras often appear more colorful and detailed than what observers perceive with the unaided eye. This is largely an artifact of low-light aurora viewing conditions. Auroras typically produce illumination levels comparable to moonlight, near the threshold of human vision. As you all know, there are two types of photosensitive cells on your retina: cones and rods. Under well-lit conditions, your eyes use cones to process light, known as photopic vision. The cones are responsible for color vision but are not responsive to low light. In very dark environments, rod cells dominate what you see, known as scotopic vision. Colors are barely perceptible under scotopic vision, leading to almost black-and-white, desaturated vision. Your eyes adapt to a low-light environment by transitioning sensitivity from the cones to the rods, which takes 20–30 minutes to complete.

While the eye’s photoreceptors are sensitive, they cannot accumulate light over time in the manner that digital sensors can. A camera sensor employs multiple mechanisms to collect more light than the eye: high ISO sensitivity amplifies the signal, long exposures integrate light over several seconds, and the full spectral response captures wavelengths across the visible spectrum.

Consequently, a faint aurora appearing as a low-contrast feature to the eye reveals more defined coloration in a photograph. As aurora intensity increases, the eye’s color perception approaches what cameras record. Additionally, wide-angle lenses compress perspective differently than human peripheral vision, altering the apparent geometry and apparent motion of auroral structures.

For the photography geeks among you, all of these photos were taken with a Nikon Z8 camera and NIKKOR Z 20mm ƒ1.8 S lens at ISO 3200, ƒ1.8, and shutter speeds of 1.0 second (occasionally up to 2 seconds).

And since this is supposed to be a post of readers’ wildlife photos, here are two images that I made near Fairbanks:

Reindeer or caribou (Rangifer tarandus):

Muskox (Ovibos moschatus):

Readers’ wildlife photos

November 13, 2025 • 8:15 am

We’re running low, but fortunately today we have some nice photos from around Hudson Bay, all taken by Ephraim Heller. Ephraim’s captions and IDs are indented, and you can enlarge the photos by clicking on them.

I visited Churchill, Manitoba on Hudson Bay in late October / early November for wildlife photography. This was my second visit to the Churchill area. Neither trip met my expectations for wildlife viewing, but I did get a few good shots to share with WEIT readers.

One night was clear and I had a ten minute window to capture the aurora borealis before it faded:

As the aurora faded I shot this Inukshuk, which is a traditional Inuit stone marker used as a navigation aid, marker for travel routes, fishing place, hunting ground, and location of reverence or memorial significance. The word “inukshuk” means “in the likeness of a human.”:

The wreck of the MV Ithaca, which ran aground in 1960:

Polar bears (Ursus maritimus) are the reason tourists come to Churchill. The primary food of the Churchill polar bears is ring seals and their primary hunting method is called still-hunting, an ambush tactic where polar bears wait by seal breathing holes in the ice. Ring seals maintain 10 to 15 open breathing holes in the ice throughout the winter by using their sharp claws. They surface every 5 to 15 minutes to breathe. Polar bears use their sensitive sense of smell to locate these holes. Bears wait motionless for many hours for a seal to surface. When a seal pokes its nose up from the water, the bear grabs the seal’s head and… well, you can guess:

Obviously, still-hunting can only be done on ice. Hudson Bay is one of the Arctic regions where sea ice melts completely each summer, forcing all polar bears ashore for an extended fasting period (other Arctic populations live and hunt on ice year-round). The Western Hudson Bay population experiences one of the longest ice-free periods of any polar bear population, historically lasting 3-4 months from late July through early November. This seasonal pattern creates what researchers describe as a “walking hibernation,” where bears must survive entirely on fat reserves accumulated during their seal-hunting season on the ice:

The local Churchill population is in decline. Extended ice-free periods due to climate change and unusual weather are blamed. Particularly hard hit are adult females and cubs, as pregnant females often lack the food necessary to successfully birth and raise cubs:

Polar bears congregate around Churchill due to its protrusion into Hudson Bay. The counterclockwise currents in Hudson Bay deposit melting ice along the coast in summer, where most bears come ashore. In autumn, these same currents cause ice floes to accumulate. Additionally, the Churchill, Nelson, and Hayes Rivers discharge freshwater into shallow coastal waters, and since freshwater freezes at higher temperatures than saltwater, ice forms earlier in this location. This early freeze-up attracts hungry bears eager to return to hunting after months of fasting:

Unfortunately, it is expected that ice-free periods may soon exceed critical fasting thresholds and that extirpation may be inevitable for the Hudson Bay populations that require seasonal ice. 2024 set a record of 198 ice-free days in Southern Hudson Bay:

The willow ptarmigan (Lagopus lagopus) undergoes a complete molt from brown in summer to white with black tail in winter:

The genus name Lagopus means “hare-footed,” referring to the feathers that completely cover their feet all the way to the tips of their toes. The feathers on the soles of their feet increase the weight-bearing surface area of their feet, acting as bird snowshoes so that they can walk on top of snow and also providing thermal insulation. Like other grouse, willow ptarmigans excavate snow burrows for roosting:

The spruce grouse (Canachites canadensis) survives winter on a diet of conifer needles. These needles are low in protein and extremely difficult to digest due to high cellulose content. To accommodate this diet, the spruce grouse’s digestive system enlarges during the winter:

Arctic hares (Lepus arcticus) maintain normal body temperature (38.9°C) during the winter while despite a depressed basal metabolic rate. A reduced surface area to volume ratio through their compact body structure, combined with insulation from their thick fur and ~20 weight % body fat, enables them to maintain homeostasis:

Willows comprise the hares’ primary food source in the barren arctic. They consume every part of willow shrubs, including bark, twigs, roots, leaves, and buds. While generally solitary animals, arctic hares “flock” during winter months. Groups can range from dozens to as many as 3,000 individuals, huddling for warmth and moving as a single body: