Category: Physics

CloudsIt’s that time of year again. Time to get out the plastic and the floating row covers, and pack water-filled bottles among the rows of plants. It’ll be a while before the orange growers have to get out their smudge pots and fans, but here in Alaska the season for radiation frosts has started, and anyone with a growing garden is hoping for cloud cover at night.


Anything not at absolute zero (-460°F) radiates energy. The efficiency of this radiation varies, but most solids and liquids other than metal are very efficient. Most gasses are very inefficient, the so-called greenhouse gasses being exceptions. At the temperatures we live at, most of this radiated energy is in the thermal infrared.

The energy has to come from somewhere. Something like pavement may get its energy from deeper down, by conduction. Ever seen those warning signs that ice may form on bridges? That’s because a bridge doesn’t have as much thermal mass as a road on normal ground, so it can lose more energy and get colder at night.

Surfaces also gain energy from radiation. We’re all familiar with the sun’s radiant energy, or the energy of a fire, which we can feel on our faces. But building walls, for instance, also radiate in the infrared. If the radiating surface is about the same temperature as our skin, there is no net energy loss or gain, so we don’t feel the exchange as warm or cold.

Conduction from (or to) the air also has to be taken into account.

One final piece of the puzzle: surfaces radiate energy at a rate proportional to the fourth power of the absolute temperature and also proportional to the efficiency with which they radiate. In practice, energy radiated increases with temperature.

On a cloudy night, the clouds radiate to the ground at the temperature of the cloud base. Unless the cloud base is below freezing, this helps the temperature near the ground stay above freezing. But what if there are no clouds at night?

It depends on the temperature of the air aloft, and the amounts of carbon dioxide and water vapor in the air. The water and carbon dioxide radiate energy down to the ground, but not terribly efficiently. It the air is cold and dry, objects without much thermal mass, such as leaves, may radiate so much more energy than they receive that they cool below freezing even while the air temperature is above freezing. This is a radiation frost.

Of course the air is cooled by the cooling leaves and ground, so often the air temperature also goes below freezing. But the leaves freeze fist.

Why do plastic or row covers help? With a cover, the energy radiated comes from all of the air trapped below the cover, not just from the leaves. Cooling is slower. It can be made even slower by putting something with high thermal mass, like bottles of water, below the cover. Keeping the air mixed with fans also helps, because since the air is cooling from the bottom up, mixing warmer air down from aloft helps keep the plants warm.

I’m keeping an eye on the weather forecasts – especially clouds!

Squash bed covered with IRT Plastic

IRT plastic in use. Note the puddled rainwater.

Some plants, like peas and lettuce, are happy enough with cool air and cold feet, but others insist that their roots be kept warm. This creates problems in areas such as interior Alaska where the ground is frozen so deeply that it may be well into fall before the soil is warm enough to satisfy corn, tomatoes, beans or squash outdoors.

It is possible, of course, to attack the problem with brute force. Build a greenhouse, or use heating cables in the soil. Mounding the soil also helps. So do raised beds. But all of these together are barely enough in the Fairbanks area.

Clear plastic allows the soil to retain the heat supplied by the sun. My own experience is that it also provides a perfect environment for weeds to grow under the plastic. Maybe they cook in warmer climates, but here in Fairbanks clear plastic can be pushed right up by rampant (and very healthy-looking) pigweed and lambs’ quarters.

Black plastic or landscape fabric? They stop weeds, and you’d think they would absorb sunlight and warm the soil. Nope. They’re not in good thermal contact with the soil, and while the black covers themselves may warm, they do not transfer that heat to the soil. Black covers have the net effect of shading the soil, lowering its temperature.

Luckily, it is possible to combine the two.

Ever seen a rainbow? Or the breaking of white light into colors by a glass prism? Then you are aware that sunlight is actually a mixture of light of different colors. What you may not know is that our eyes are sensitive to only part of those colors, and that growing plants need mostly the same colors that we can see. But only about half of the energy of sunlight is in these colors. A little bit is in the ultraviolet, the part of the solar spectrum that tans and sunburns our skin. That’s only a small fraction, and most of that is stopped by the ozone in the atmosphere. A much larger part of the invisible energy is in the near infrared.

Most of this near infrared energy passes pretty freely though most substances (such as air) that we consider clear. It is a large part of what makes sunlight feel warm. But plants cannot use it to photosynthesize, so if they get only near infrared light they cannot grow. No weeds!

IRT stand for infrared transparent, and IRT plastic allows the near infrared radiation through to warm the soil, but blocks the visible radiation that would allow weeds to grow. I’ve been using IRT ground covers to grow squash and beans for years, even though I grow them in raised beds.

It does have one problem: it’s waterproof. At one time, I could find it with microscopic holes that let rainwater drain through to the soil underneath, but all I can find now allows rainwater to puddle on the surface and the soil to dry out underneath. Until this year, I had to carefully shape the soil so that the plants (and the holes for them in the plastic) were in low spots. This year I’m trying something new. What? I’ll tell you when I know whether it works, but if you look, it’s visible in the photo.

Weight Gain

“Calories in – calories spent = weight gain.” Sounds simple and rather obvious – conservation of energy, right? But as applied, it makes some rather bad assumptions. And as many will testify, it doesn’t seem to work.

To start with, caloric input is NOT the same as the calories you eat. To some extent this is recognized. Cardboard has calories, but there is no way a human body can use them. While fiber (cellulose or soluble fiber) is often excluded from calorie counts, even digestible calories may not always be digested. The true caloric input is the calories your body is able to turn into glucose and lipids in your blood stream. I suspect that people vary quite a lot in how efficient their digestive systems are, and that may even vary with time for the same person. Certainly variation with time could help explain the “set point” for body weight.

Inefficiency in our digestive system? There are digestible calories in what comes out the other end, and not just in diabetics who lose sugar in the urine. Pigs and dogs scavenge human feces, among other things, if given a chance. It is the difference in calories between what we eat and what comes out that is the important energy input, and there has been very little study of how much that form of energy out might vary.

Then there is energy usage. Certainly exercise, even walking, burns more calories than simply sitting. But it takes energy to keep our body temperature up, our heart beating, our lungs expanding and contracting, and especially to keep those big brains operating. Sitting as quietly as you can in a cool room may burn a good many calories, though I wouldn’t recommend it as a way to lose weight. (It is, however, recognized as one of the reasons people working in the cold may need more calories. If your body is very efficient at all these “housekeeping” tasks (low basal metabolism) you may need fewer calories to maintain constant weight than someone whose basal metabolism is higher.

For that matter, some people may use their bodies in exercising more efficiently than others.

I strongly suspect this is an oversimplification of what seems to be a near-epidemic of excess weight. I certainly wouldn’t argue with the idea that something in our environment (including our food environment) is tinkering with the efficiency of our digestive processes, though I suspect serving size has a lot to do with it. But why don’t we ever consider calories out? It would be simple enough in test animals, if not in humans.

The usual four seasons, especially as defined by the equinoxes and solstices, don’t work very well for interior Alaska. Show cover is generally established by a month after the autumnal equinox, and stays on the ground until well after the vernal equinox. Rivers freeze a little later and remain frozen longer in the spring, and the only running water for six months of the year is in hot springs and indoors. But there is one season that everyone both longs for and dreads: Breakup.

Breakup is the time of year when snow melts and rivers thaw. The two are connected by more than sunshine and warmer weather. Melting snow makes mud (one of the reasons breakup is a time of some dread) but it also runs into rivers. If the water rises in the upper stretches of a river before lower reaches are thawed, as often happens in Alaska, the result can be ice jams and resultant flooding. I’ll talk about that some other time, but right now I want to discuss the simple process of melting snow.

Clean snow reflects most of the solar energy that strikes it. Some of the sun’s rays are absorbed within the snow pack, and cause internal melting and settling — but this is a slow process. Even clean snow, however, is a very good absorber in thermal infrared wavelengths. The sun doesn’t put out much energy in these wavelengths, but buildings, trees, and just about everything else except polished metal does. As a result, snow near the south side of a building melts much faster than snow out in the open. So does snow near tree trunks.

I see this every year. In addition to the photo of my road, which is rapidly turning into mud, I took two of the north and south yards of my house, minutes apart. Both areas got almost exactly the same amount of snow, and both have very similar exposure to sunlight. The snow stake still has a good 18” of snow. The ground around the birch is almost bare.

Why? Two reasons, actually, and the combination explains why open birch forest is usually the first natural area free of snow around here. First, birch trees hold their seeds through winter, and drop them shortly before breakup. As a result the seeds on the snow around the tree absorb the solar radiation and transfer that energy to the snow, speeding its melt. Natural selection? Quite possibly. It certainly seems likely that the enhanced snow melt, leading to earlier warming of the ground, would help the tree.

Second, the tree itself absorbs some solar energy, and then re-radiates it to the snow in the form of thermal infrared. Just about any object poking through the snow this time of year has a little depression around it. Spruce trees do an even better job of absorbing sunlight than do birches, but they also shade the ground and transfer much of the energy they absorb directly to the air. As a result spruce forest, while it probably does a better job of warming the air than birch forest, is among the last areas to have completely bare ground.

On a different note entirely, one of the fixtures of breakup in Fairbanks is the Beat Beethoven 5 km race, a fundraiser held today for and by the Fairbanks Symphony Orchestra. I won’t be running this year, though I did “run” with a cane once — and came in last. The idea is to cover the 5 km before the end of Beethoven’s 5th Symphony, about 30 minutes. I’m volunteering this year to park my car along the race route with the radio tuned to 91.5 (KSUA, the campus radio station) blaring out Beethoven’s 5th. I expect temperatures below 50°F and much of the course to be slippery or wet!

Added later (after the race.) This is definitely a family race. There were parents pushing their children in strollers, parents with children in backpacks or riding piggyback, dogs, and one contestant on crutches. (And she wasn’t at the end, either.) I did have a bit of a problem in that instruction to volunteers said if possible, not to have your car idling as the runner went by. I did. And needed a jump to start the car after the battery totally discharged itself.

This pile of white ice chunks was scraped off the OLLI parking lot. As you can see, the lot is still white.

I’ve talked about snow that is undisturbed without a temperature gradient, and about disturbed snow without pressure. Today we’re going to take that a step farther and look at snow that is disturbed by pressure—specifically, by car or foot traffic—when temperatures are below freezing. Here in Alaska we call it white ice, and the less-traveled roads and almost all the parking lots are solid white ice this time of year.

Wind or an avalanche will break snow crystals, but it doesn’t in itself press the broken grains together. Walking or driving over dry snow, however, not only breaks the crystals, it also presses them together. If it is near freezing, the pressure may even cause slight melting. In any event the crystals are very firmly welded together. The result is a mass that has some air trapped—that’s why it looks white. But it may be only a little less dense than ice, and is only slightly softer. An icebreaker or a sharp-edged shovel will generally break it much more easily than it will break true ice, but white ice is definitely solid.

Some of the chunks of white ice removed from the road I live on.

As a driving surface, white ice is something most Alaskan drivers learn to deal with. It is not impossibly slippery if it is not polished or near freezing temperature, though most of us drive on it with caution and learn to feather our brakes. Mine are anti-skid, but I’ve learned to brake softly enough that the anti-lock feature almost never engages—except at intersections.  Those are often polished to the point that they are extremely slick, even though graveled.

Yes, graveled. We don’t use salt much because our temperatures are generally so low that even salt water freezes and salt simply will not melt ice. Salt’s used on sidewalks sometimes, but in cold weather each salt pellet simply melts its way down to the pavement without having much effect on the main ice mass—except to make it slicker.

Notice the step left when one lane of my road was plowed a couple of days ago.

The road I live on is gravel, and a coating of white ice actually improves it. But it does do some things you might not think about to paved roads.

First, it covers any marking painted on the road or parking lot—lane markings, turn arrows, lines that mark parking spaces.

Second, it can at times be thick enough that when part of a road is cleared in the spring, a considerable drop-off may result.

Third, and especially a problem when it is overcast and the light is flat, is whiteout conditions. It’s not as bad as in an airplane north of tree line when the pilot may not even be able to see which way is up, but telling what is road and what is not can be very difficult when the road is white ice and the verge is snow and both are exactly the same color. It’s hard to see even with directional light and shadows, but in flat light everything looks the same.

I managed to high-center my car a few weeks ago taking an exit between a four-lane highway and a major side road. The exit was pure white ice, and I couldn’t quite see what was road and what was the curbed triangle between the side road and the exit. I wound up on the triangle and had to be pulled off by a tow truck. Neither the trooper who stopped to see if I needed help nor the tow truck driver seemed to have the slightest problem understanding how I’d gotten there, or even consider my situation unusual. “Whiteout”  was all the explanation I needed.

Ever notice that the berm across the end of your driveway, or the one formed when you shovel the sidewalk, is harder than the undisturbed snow? That’s because when snow is disturbed crystals are broken, and the broken surfaces positively grab onto other ice surfaces. Two examples of this are common in nature, and I’ve used both in my fiction writing.

The first is called a wind slab or wind crust. When a turbulent wind picks up snow crystals and redeposits them, a good deal of crystal breakage takes place. When the broken crystals settle down they weld themselves to other crystals and the result can be a hard crust—even though the temperature is below freezing. Roi has to cope with this in Tourist Trap:

The trees had broken the force of the wind up to now, but once he entered the open swath the wind almost knocked him off his feet. The snow was crusted here, not quite enough to hold his weight, but enough that his thighs were bruised repeatedly by the chunks of wind-slabbed snow he was dragging Timi through. He paused twice to increase the circulation to his feet. Were they cold, hurting like hell, or just numb? he wondered absently, and then realized that Timi’s shields had dropped to the point that he was feeling Timi’s body as well as his own. The wind cut through the frozen scarf and the cold glued his eyelashes shut, and with a start of horror he realized that he had drifted away from the line back to the shelter. He could teleport himself back, maybe—but he wasn’t sure he had the energy left to do even that, and there was no way he could take Timi with him.

He struggled on: lift a leg and break the crust with his knee, then drag the leg through the slightly softer snow underneath until he could balance on that leg to break out the next step with the other leg. Timi staggered behind him, almost falling several times, and his mind ached from the effort of keeping the other boy upright. Snow had sifted into his clothing, somehow, and he knew he was cold but no longer felt it. With an abruptness that caught him by surprise, the wind died down, and he went to his knees as he tried to break through a crust that was no longer there. Back in the trees, he finally realized, and reached out for the faint impression of the shelter.

The second is probably less familiar to most, and I hope it remains so, but here in Alaska it is constantly being drummed into us. This is what happens in an avalanche. The churning snow sets up like concrete as soon as it comes to a halt. Well, not quite like concrete — it can be dug through with shovels – but far too hard to shift by moving your body. Marna is caught in an avalanche in Homecoming:

Even as she crouched and aimed herself for a belt of trees that might provide some protection, the leading edge of the avalanche overran her, tumbling her helplessly down the slope. The churning snow caught and twisted one forceweb until she thought her leg would break, but the torsion activated the safety cutoffs and the forcewebs went abruptly inert. She clawed her way upward through the fast-moving snow, and tried to remember what lay downhill. Only her perceptive sense kept her from total disorientation.

The buffeting and spinning as she was carried along reminded her of the time she had been caught in the breaking wave—but then Win had been there to rescue her. Win. She had repudiated whatever was left of Win, but as the slowing mass suddenly set rigidly about her body, she wondered at her own insanity in wanting to be alone. She struggled to move, but felt only the slight snapping of a switch, followed by the growing cold of the snow that held her prisoner. Her struggles must have turned off the thermal suit, she realized with a growing sense of despair. Exhausted and chilled, she could not even visualize a place of safety. Win, she sobbed mentally. Forgive me, my love.

This is a situation where time is absolutely essential, and buried but living victims are likely to die of suffocation or cold – often in less time than it takes to get help. Dogs are better than people at finding victims, but if search and rescue dogs have to be flown in, it is often too late to find anything but a body.

The Ice Art Championships are underway! I’ll show some of the competition pieces next Saturday. But I did pick up a season pass and have a look at the kids’ park. If the weather cooperates, I hope to get some photos of more than just this bit close to the entrance.

This one's very interactive--kids (including some quite large ones) can get into the dish and be spun around.

For a while we were afraid we’d lose the World Ice Art Championships. They’ve been held for years on land owned by the Alaska Railroad. Something happened last year—I think the railroad raised the rent, but I’m not sure, and for a while the organizers were frantically hunting a new site. Well, they’ve found a permanent home and while it’s still rather raw, it promises to be as spectacular as the old one.

This one is actually a slide. Sorry there isn't more contrast with the sky.

As I said, I only got to see the kids’ park Saturday, but I did take a few photos. Even the slides and the sculptures to climb on are pretty neat. The train sounds like a good idea once I figure out where the station is. I went again on Monday, and got some more photos of the kids’ park, plus took enough more for several more posts. Watch for them.

Isn’t our Alaskan ice beautifully clear?

Note: you can click on any of the photos to see larger versions.

The sabertooth cat can be ridden, but you'd better have insulated pants!

This dragon is saddled and ready for kids to ride.

More slides

Guess who sponsored this one!

Fog, Fog and Fog

Freezing fog. That term has been used by the local radio station lately to refer to ice fog. (At least, that’s what I think they mean.) There are at least three different kinds of fog made of oxygen dihydride (water.) None of them are well described by the term freezing fog.

The first and commonest, which I will refer to as warm fog, is certainly not freezing fog. It is composed of very small drops of liquid water, with the temperature above freezing. This kind of fog is what is  stable: the droplets do not collide, grow and fall out, and seeding is useless. Many low-level clouds are exactly like this kind of fog, and they very rarely initiate rain. The only situation in which this type of fog could produce anything that might possibly be called freezing fog is if it is carried over a surface – road, wire, or tree branch – which is well below freezing. This might happen in Alaska if we have had a week at 40 below and we suddenly get a warm fog, but it is certainly not common.

The second kind of fog, which produces ice storms and can be dissipated by seeding, is supercooled fog. This is a fog made up of liquid droplets which are below freezing temperature. It is very common in clouds well above the ground, where it is responsible for aircraft icing.

Liquid water? Below freezing?

Ice melts at the freezing point, but water does not automatically freeze. Ice has an ordered crystal structure, and you can think of liquid water at temperatures below freezing as needing a little shove to get the molecules into the right order. Something that helps produce that order is known as a freezing nucleus. The best nucleus as actually a splinter of ice, but there are many other possibilities. A reasonably large volume of water usually has some impurities that will act as ice nuclei at temperatures only a little below freezing. Also, if a tiny droplet hits almost anything it will freeze. But that same droplet, floating in the air, may remain unfrozen at temperatures quite a bit below freezing.

The colder it is the more things are available to act as nuclei, and in clouds, the most dangerous temperatures for icing are generally above 0°F. So fogs of temperatures below freezing but above 0°F are very likely to be supercooled fogs. They can be dissipated by seeding, but they can also be responsible for ice buildup on streets, wires and branches. (Ice storms can also be caused by rain falling through sub-freezing air, but supercooled fog alone is enough.)

Fogs at temperatures between 0°F and -20°F are actually quite rare in nature. Below -20°F, and especially at temperature approaching and below -40°F, a third type of fog may appear: ice fog.

Ice fog is made up of tiny spherical droplets, and looks just like any other fog. The difference is that the droplets are ice. You could call ice fog frozen fog, though not freezing fog. In nature, ice fog is pretty well confined to temperatures below -40°F, as water droplets freeze without needing a nucleus at around that temperature. A source of water is needed, so natural ice fog tends to occur around herds of caribou or warm springs. (Yellowstone was actually used for some early ice fog research.)

In built-up areas, combustion produces not only water vapor, but some ice nuclei. Consequently some water droplets freeze and some do not, and the ones that freeze are able to grow a bit by vapor growth from the evaporation of those that don’t freeze. Some ice fogs at relatively warm temperatures may even grow into well-formed ice crystals, and produce some of the optical effects often associated with ice crystals.

You are very unlikely to see ice fog unless you live in an area where 40 below temperatures are common, but fog at temperatures below freezing is likely supercooled fog. Supercooling, by the way, is very important in the formation of most raindrops — but I’ll talk about that some other time.

No, they weren’t dinosaurs. True, model sets of extinct animals often include saber-tooth cats, sail-backs (which were mammal-like reptiles and more closely related to us than to dinosaurs) and extinct marine reptiles as well as pterosaurs, but none of these are actually dinosaurs. Pterosaurs did, however, live alongside dinosaurs and are of great interest as the largest animals ever to fly on their own.

This DVD, another of the National Geographic series, looks at the mystery of pterosaur flight. As usual, the animation is not very exciting, but the scientific work and the attempt to build a mechanical pterosaur more than makes up for that.

The big questions are, how large did pterosaurs grow and how did they fly?

One of the threads of the program is the rather controversial discoveries of trackways and fossils suggesting even larger pterosaurs than Quetzalcoatlus, which itself had a wingspan of 10 meters (33 feet.) That’s three times larger than an albatross, the largest flying bird alive today. Forget the giants; how did even the ones we’re reasonably sure of fly?

The meat of the DVD, as far as I was concerned, was an attempt to build a robotic pterosaur, controlled like a model airplane. The result was not wholly successful, but a great deal was demonstrated about pterosaurs in the process.

First, pterosaur wings were a good deal more complicated than the sailcloth that was first tried. They had oriented stiffening fibers, muscles within the wing membrane, a good blood supply to the wings, a furry covering that (like the dimples on a golf ball) helped aerodynamically, and some kind of built-in sunscreen. (Bats are nocturnal in part because their wings would sunburn too badly in daylight.)

Control was incredibly sophisticated, certainly more so than could be mimicked by a model airplane controller. Much of the maneuvering of a real pterosaur was probably as automatic as keeping your balance is to you – possibly more so, if the speculation that baby pterosaurs were born knowing how to fly is correct. Changing the shape of the wings and the tilt of the head would have been automatic for a real pterosaur. Not so for the model, and it is hardly surprising that it was not fully successful, even aside from the problems of finding components and power sources of sufficiently light weight. Pterosaurs, like birds, had very light bone structures.

As entertainment this DVD falls short. But as documentation of a fascinating experiment, it is worth watching.

Here are links to all of the posts I would count as science, including those that explain how I use science in my science fiction. This list will be updated as new science posts are added. (Note that some posts listed under “Health” or “Technology” may also be of interest.)

The Science Behind Homecoming 4/2/10
Why do we have Weather? 4/24/10
Precession – Astronomy and Milankovitch 5/6/15
The Four Horsemen of the Apocalypse 6/12/10
Why Planets Have Seasons 6/24/10
Full of Sound and Fury (Fireworks) 7/3/10
Tricycles are not Bicycles 8/8/10
Planet Building 8/15/10 – 10/24/10
Racemization 9/2/10
Equinoxes and Daylight Savings 9/23/10
Horse Color Genetics 10/31/10 – 5/8/11
R’il’nai, Humans and Crossbreds: Life Span 12/11/10
Conservation Laws of Energy and Teleportation 12/20/10
Winter Solstice 12/22/10
Mass into Energy 12/24/11
Momentum and Teleportation 1/1/11
Snowflakes 1/7/11
Ice Fog: Ground Level Contrails 1/25/11
The Planets of Tourist Trap: Eversummer 3/6/11
Earthquakes, Tsunamis and Volcanoes 3/13/11
Why 12-Hour Days Already? 3/19/11
Ice Sculpture: Ice and Sun 3/26/11
More on Ice Melting 3/27/11
Why Temperatures Remembered Don’t Match the Record 4/5/11
When It’s Springtime in Alaska 4/8/11
Twilight 4/12/11
How High the Moon? 4/15/11
Breakup 4/16/11
The Cambrian Explosion 4/22/11
How Did We Learn to Walk? 4/29/11
Back to the Water 5/6/11
Where did the First Plants Come from? 5/13/11
The Geophysical Institute 5/15/11
Alaskan Mosquitoes 5/19/11
Colored-Leaf Geraniums 5/20/11
Early History of the Geophysical Institute 5/22/11
The Fairbanks Flood of 1967 5/29/11
Before Computers 6/5/11
Ice Ages and Alaska 6/17/11
Cumulus Clouds and Cloud Streets 6/24/11
Plate Tectonics Part I 7/1/11
Plate Tectonics Part II 7/8/11
Plate Tectonics Part III 8/5/11
Frost Hollows 8/19/11
Be Careful What You Ask For 8/27/11
Autumn Colors 9/10/11
Thermometers in Fairbanks 9/17/11
Junk Mail and Plants 9/20/11
The Chimney Sweep 9/22/11
Lights, Batteries, Temperatures? 9/24/11
How Dry I Am 10/15/11
Keeping Windows Dry 10/22/11
Snowflakes 10/29/11
The Alaskan Mesozoic 11/1/11
Mesozoic Alaska Part 2 8/11/11
Alaskan Mesozoic 3 11/15/11
Death of Blue Babe 11/17/11
Nightlength Sensitivity in Houseplants 12/10/11
Our Sense of Smell 12/17/11
What Time of Day is Warmest? 12/31/11
Alaska Winter Weather: Cordova and Nome 1/14/12
Inversions and Smokestacks 1/28/12
January Wasn’t Warm in Alaska 2/4/12
Fog, Fog, Fog 2/11/12
Oceanography DVD Review 2/14/12
Snow Festoons 2/18/12
Disturbance Hardening of Snow 3/24/12
Cold-Packed Snow and White Ice 3/31/12
Tornadoes and Climate Change 4/7/12
Breakup Season 4/14/12
Ice Jam Floods 4/21/12
Calories and Weight 5/5/12
Battery Woes 5/12/12
IRT Plastic: Using the Sun 6/2/12
A Love Affair with Begonias 6/7/12
The Transit of Venus 6/9/12
How does Rain Form? 6/16/12
If Earth were on its Side 6/22/12
Day and Year Lengths of the Planets 6/23/12
Chickweed and Mosquitoes 6/28/12
Flowers and Sex 6/30/12
Salpiglossis (Painted Tongue) 7/5/12
How Long is your Night? 7/7/12
Colorado Storm 8/2/12
Could Jarn have Made Glass? 8/11/12
Seeing the Jet Stream 8/18/12
A Bird in the Hand 8/23/12
Radiation Frosts 9/1/12
Alaska Sky 9/25/12
Sky Photo 9/27/12
Flower Photos 10/9/12
Start of the Seasonal Snowpack 10/18/12
Sunrise and Sunset in Fairbanks (video) 12/27/12
Video from Barrow, Alaska the first day of Sunrise 1/24/13
We Have Puddles! 4/20/13
DNA: We All Have it 6/1/13
My Maternal DNA 6/8/13
Winter Solstice in Fairbanks 12/21/13
Glaciation 4/8/14


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