I hate to be the bearer of bad news, but…it’s winter. As I write this it’s -28 outside, huge piles of snow line the streets, and tow-truck operators are gainfully employed all over the city.
Winter is on everyone’s minds, which must be why I was recently asked several winter-related questions by Colin Grewar, host of CBC Radio’s Afternoon Edition. Such as:
Q. Is it true no two snowflakes are alike?
It depends on your definition of “alike.” A snowflake begins when water inside a cloud condenses and freezes on a speck of dust or other particle. This tiny crystal grows as it falls, collecting more water vapour on its way. The V-shape of water molecules insures that the crystal will be six-sided, but the exact shape depends on temperature and humidity. Because these change every few centimetres in the atmosphere, each additional bit of water vapour freezes to the snowflake in a different way. Every flake is a record of all the atmospheric changes it experienced between cloud and ground.
To resemble each other, two snowflakes would have to pass through exactly the same atmospheric conditions in exactly the same order for exactly the same amount of time. One estimate is that there are a million different combinations of temperature and humidity a snowflake might pass through as it falls, which makes the odds against two crystals passing through exactly the same conditions in exactly the same order approximately one-with-five-million-zeros-after-it to one. Since the total number of snowflakes that have fallen in Earth’s entire history is only around one-with-a-mere-35-zeroes-after-it, it’s highly unlikely any two have been the same. (A scientist in Colorado did recently find two nearly-identical snowflakes, but they arrived side by side on her microscope slide and so were probably joined together throughout their fall. That doesn’t count.)
Q. What was Regina’s worst winter?
It depends. Fraser Hunter, a meteorologist with Environment Canada, did some digging for me, (defining winter as December, January and February), and came up with these figures. 1972-73 was the snowiest, with 95.5 centimetres (40.7 centimetres of which remained on the ground at the end of February), but its mean temperature was only -16.6, 35th coldest. 1886 was the coldest year on record, at -24.4, but it ranked 93rd in terms of snow: only 10.2 centimetres fell. So your choice for worst winter depends on whether you hate cold or snow the most.
Provincially, Stony Rapids suffered the coldest winter on record: in 1971, the mean temperature there was only -28.4. Prince Albert has the dubious distinction of recording the coldest temperature on record: the mercury dropped to -56.7 there on February 1, 1893.
Q. Why don’t we get thunder and lightning in winter storms?
Lightning is an exchange of electricity between a region of the atmosphere with a strong negative charge and a region with a strong positive charge (or the ground). Air movement separates the charges. The towering cumulonimbus clouds out of which thunderstorms originate have very strong air currents inside them. The kind of clouds that give us snow don’t: as a rule, the air is far less turbulent in the winter than in the summer.
That’s mainly because turbulence is the result of warm air rising and cold air sinking, and there’s much less difference in temperature in a winter cloud than there is in a summer cloud. In a big thundercloud, the temperature can vary from +30 at the bottom to -60 at the top. In the winter, everything is roughly the same temperature: cold. Also, there tends to be a difference in electrical charge on either side of the “zero-degree isotherm”: the interface between above-freezing below-freezing temperatures. In the summer that’s usually two or three kilometers up. In the winter, it’s usually ground level: there IS no air that’s below freezing.
When thunderstorms do occur in the winter–as they did in a big blizzard in Winnipeg in the late ’80s–it’s usually because there’s been a sudden influx of very warm air over top of very cold air.
Q. Why do extension cords get brittle in the winter?
Heat is the vibration of molecules. The warmer something is, the more its molecules vibrate, and the looser the bonds among the substance’s molecules. The colder something is, the less its molecules vibrate, and the more tightly they bind together. At -40, the molecules in your extension cord’s insulation grip each other so tightly they have very little “give” left. Instead of bending, under pressure they lose their grip entirely, and the insulation cracks or even shatters.
Q. What happens when water freezes?
As I mentioned, water molecules are V shaped: two hydrogen atoms, the arms of the V, bind to an oxygen atom at the point of the V. The oxygen atom attracts electrons more strongly than hydrogen atoms, so its end has a slight negative charge, while the two hydrogen ends have slight positive charges. The positively charged arms of each V bind with the negatively charged points of others.
This rather awkward arrangement results in a very inefficient in its use of space when the water molecules bind most tightly together, as they do in ice: so inefficient that cold liquid water (in which some molecules are free to break loose and slide around other molecules without attaching to them) actually takes up less space.
This means that when water freezes, it expands, unlike almost every other substance, which shrinks. Ice is therefore less dense than water, which is why it floats–and it’s a good thing it does. The expansion of water when it freezes kills plants, because the water in their cells expands, rupturing the cell walls, and bursts frozen pipes. But it’s vital to life: if ice did not expand, and therefore did not float, every year the ice that formed on the surface of lakes and the ocean would sink to the bottom, killing all life. Any deep body of water would be reduced to a vast lake of ice with a little meltwater on top during the warmest months, and the whole planet would be gripped in a permanent Ice Age.
Q. What happens when you put your tongue on a cold metal object?
Your tongue is wet. The water freezes almost instantly to the cold metal, and the bonds among the frozen water molecules and between the ice and the metal are stronger than the bonds between your skin cells, so if you pull back suddenly your cells stay with the ice and you suddenly find a large chunk of skin painfully absent.
I should know: when I was a kid a family friend gave me an antique bugle which I left in the car one cold winter’s night. A few hours later I went out to the car and, anxious to play my new acquisition, put it to my lips, realized I’d just done something stupid, yanked it away–and left a nice little circle of skin on the mouthpiece. I still cringe at the thought.
In fact, I cringe at the thought of winter, period, and frankly, I don’t want to write about it any more.
