This happened in my friend's henhouse this morning.

My friend Kate Hastings, who took this photo, thinks this egg froze because the hen cracked it slightly. But it also looks like the kind of expansion cracking that you can get when eggs freeze and burst their own shells. When the water in the egg white and yolk freezes, it forms a crystalline structure — and that structure isn't very tightly packed. There's lots of space between the molecules, which means that solid ice takes up more space than the liquid it replaced. If the egg freezes solid enough, it's got nowhere left to expand except outside the shell.

Eggshells, as it turns out, are not a great insulator from the cold. Chicken butts are, but chickens also don't always sit on their eggs consistently enough to keep those eggs from freezing.

One side note: You can actually thaw and eat frozen eggs. But you shouldn't thaw and eat an egg like this. That's because the shell is actually a pretty good barrier against bacteria. If a fresh egg — the kind sitting under a hen — has cracked, there's a higher likelihood of bacterial infiltration.

They're the mullet of cold-protective clothing. Half glove, half mitten — really, fingerless gloves with a handy mitten flip-top.

They are also fantastic.

Now, partly, this is a matter of personal opinion. But partly, it's just good science.

Before you spend your weekend outdoors, or take your next chilly commute, let's talk briefly about glittens — and the science that makes them superior hand covering.

There's really two things going on here.

First: Mittens are warmer than gloves.

I spent years feeling like I failed at gloves. Even high-quality Isotoner-type things couldn't keep my fingers warm. At least, not for very long. After 10 or 15 minutes, my fingers would start to go numb and cold. The only way I could keep them comfortable was to slide my fingers out of the finger holes and ball up my hand inside the wide part of the glove. (At which point you become Edward FloppyFingers.)

And there's a very good reason for this. It has to do with the way we get cold.

Everything wants to be the same temperature. Hot things and cold things want to match, rather than be different. At the same time, it takes energetic work to make things hot — whether that's a furnace pumping in your basement, or the sun burning in outer space, or your body metabolizing food. Without those inputs, everything is cold. (Eventually, everything will be cold. Inevitable heat death of the Universe and all that.)

So hot things are special. And when they come into contact with cold things, heat moves from the hot thing to the cold thing, and the hot thing cools down. In fact, the bigger the difference in temperature between the hot thing and the cold thing, the faster the hot thing is going to become cold.

There are several ways that this heat transfer can happen, but when we're talking about your hands and the cold air, we're talking about convection — the transfer of heat between a solid object and a fluid. (My husband, an HVAC engineer, refers to this as, "One of my three favorite kinds of heat transfer.")

Cold air moves over your hands. Your hands and the air try to become the same temperature. Your hands get cold. You can't stop this process, but you can interfere with it, and that's what hand coverings are all about. Insulation — the cloth of the glove or mitten — creates a barrier between your warm hand and the cold air.

It's not a perfect barrier. But now the thing that is most in contact with your hand is closer to the temperature of your hand. With less of a temperature difference, heat transfer slows down.

But there's another factor that affects heat transfer — surface area. The more surface area on the hot thing, the more it comes into contact with the cold thing, the faster it loses heat. Gloves put more surface area in contact with cold air than mittens do. So they won't keep your hands as warm as the same amount of insulation in a mitten will. What's more, gloves force each finger to fend for itself. In a mitten, fingers are in direct contact with other fingers. They can share heat through the solid-object-to-solid-object process of conduction and help keep each other at a relatively stable temperature.

Downside to mittens: You can't use your cellphone, or your house keys, or really anything that requires you to be more dextrous than the average 18-month-old.

Second: Glittens offer more manual dexterity than mittens.

With the science firmly established, we now get into the personal preference portion of this review. From my experience, glittens offer all the warmth of mittens, plus the manual dexterity of gloves. In fact, with their help, I've stood outside in Minneapolis at a bus stop for 30 minutes while playing with my Android phone. I had to switch hands a few times. But, overall, my hands and fingers stayed warmer, longer — even with occasional fingertip exposure to the cold air — than they do when completely covered by gloves.

In mitten mode, my fingers are better protected and they can heat up each other. In glove mode, I can work my phone's screen. It's a win-win situation. And it's all thanks to thermodynamics.

READ MORE:
A Harvard animation by Dale Muzzey demonstrating the importance of surface area to heat transfer — and other things.

Image: IMG_6027crop, a Creative Commons Attribution (2.0) image from 97793800@N00's photostream

Made a coloured ice igloo while visiting my gf in Edmonton, Canada. The local news station did a story on it. News article in comments (imgur.com) (via Colossal) ]]> http://boingboing.net/2013/01/05/rainbow-colored-igloo.html/feed 21 http://boingboing.net/2012/12/27/how-to-instantly-turn-water-i.html http://boingboing.net/2012/12/27/how-to-instantly-turn-water-i.html#comments Thu, 27 Dec 2012 18:16:27 +0000 Maggie Koerth-Baker http://boingboing.net/?p=203007

Chalk this up under "Blogs You Ought to be Following". The Tumblr Fuck Yeah Fluid Dynamics is a great place to find succinct, clear explanations of the forces that make things flow. In particular, they're fantastic at posting explanations behind things you see in YouTube videos, both viral and obscure.

The video above — in which a nice Siberian guy tosses boiling water off his balcony and creates a cloud of snow — has been making the rounds recently. Here's how Fuck Yeah Fluid Dynamics explains it:

Several effects are going on here. The first thing to understand is how heat is transferred between objects or fluids of differing temperatures. The rate at which heat is transferred depends on the temperature difference between the air and the water; the larger that temperature difference is the faster heat is transferred. However, as that temperature difference decreases, so does the rate of heat transfer. So even though hot water will initially lose heat very quickly to its surroundings, water that is initially cold will still reach equilibrium with the cold air faster. Therefore, all things being equal, hot water does not freeze faster than cold water, as one might suspect from the video.

The key to the hot water’s fast-freeze here is not just the large temperature difference, though. It’s the fact that the water is being tossed ...

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Plants and animals have to adapt to live in high latitudes and chilly mountain environments. With animals, we kind of instinctively know what makes a creature cold-weather ready — thick, shaggy fur; big, wide snowshoe paws. But what are the features of cold-weather plants? It's one of those really interesting questions that's easy to forget to ask.

At The Olive Tree blog, Tracey Switek has at least one answer. In cold places, you see more plants that grow in little mounded clumps. Of course, plants can't really rely on huddling together to create warmth. So you still have to ask, "Why is it better to grow in a mound when it's cold out?"

The dome-like shape which the cushions tend to take (made possible by an adaptation that makes all the plants in the clump grow upward at the same rate, so no one plant is high above all the others), and the closeness with which those plants grow, makes these clumps perfect heat traps. The temperature on or inside a cushion can be up to 15 °C more than the air temperature above it. The cushions are able to retain heat radiating up from the soil, as well as absorbing heat from the sun (a very dense, large, clump of green can get surprisingly warm on a sunny day at high altitude). Add to that the fact that the wind speed in and around a cushion can be cut by up to 98% from open areas, you have a perfect recipe to prevent heat loss. Many alpine cushion plants also have very hairy leaves, which trap even more heat within. This allows the plants to maintain a relatively stable, warmer than average microclimate that is resistant to sudden changes in weather and temperature outside (such as freezing temperatures at night or sudden storms). Interestingly enough, this stabilizing effect can also be a benefit when it gets too hot out, maintaining lower temperatures against baking sunshine.

Very cool!

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Image: Michael Haferkamp, via CC

Not all snowflakes are unique in their shape. There's one fact for you.

And here's another: The shape of snowflakes — whether individually distinct or mass-production common — is determined by chemistry. Specifically, the shape is a function of the temperatures and meteorological conditions the snowflakes are exposed to as they form and the way those factors affect the growth of ice crystals.

This short video from Bytesize Science will give you a nice overview of snowflake production and will help you understand why some snowflakes are unique, and why others aren't.

Twin Cities Boingers will be meeting up this Saturday afternoon. The meetup is ostensibly scheduled around the Art Sled Rally in Powderhorn Park, but will still happen even if there isn't enough snow on the ground for the sleds to, you know, sled.

Emily Lloyd has graciously volunteered her house, across from Powderhorn Park, as the location of the meetup. We'll meet at 3216 10th Ave South at 1:00 — BYOB and a snack to share. Then, at 2:00 (King Boreas willing) we'll cross the street to watch some awesome sledding action!

See you there!

Hey, guys, I figured out where all of Minnesota's winter snow went. It's in Cordova, Alaska.

Since Nov. 1, storms have dropped 176 inches of snow and more than 44 inches of rain on the town, about 150 miles southwest of Anchorage.

Temperatures warmed overnight, and residents awoke to standing water because of stopped-up drains. The rain also made the existing snow heavier.

The warmer temperatures - about 35 degrees midday Wednesday - brought another hazard to the Prince William Sound community of 2,200 people: avalanche danger.

There's one road leading out, and it was closed though it could be opened for emergency vehicles.

"We have the National Guard right now using the standard shovel, and they're getting pretty trashed every day - not the shovels but the Guardsmen themselves," he said.

That's from an AP story in the San Francisco Chronicle. Read the whole thing to learn about the intricacies of snow shovel design, and why a standard shovel just ain't enough to deal with 176 inches of snow. Better ones are being airlifted in.

The image above—taken by the Alaska Division of Homeland Security and Emergency Management—gives you an idea of what it's like to dig out of a snow pack like this. I will admit, as much as I realize what a disaster it would be to live in Cordova, Alaska right now, there is a part of me (the part that is approximately 5 years old) that just looks at this photo and thinks, "I will build the most AWESOME fort EVER!"