Baby, it's cold out there

Posted by Daniel Pendick
on Tuesday, February 06, 2007

The top story this week in our part of the country is the Arctic air mass that has settled over the land, cracking water pipes, chapping lips, and closing schools for fear that students would turn into popsicles waiting for the bus. Forecasters whipped the populace into a frenzy with threats of wind chills in the negative double digits. For cosmic irony perhaps, note that the latest global-warming forecast by the Intergovernmental Panel on Climate Change was unleashed in the midst of the big chill.

Planetary scientists might take a dimmer view of all the hoopla this week over the falling mercury. Speaking of Mercury, the planet closest to the Sun offers some contrasts in temperature unmatched in the solar system.  It reaches 660° F (350° C) in the day and then plunges to –274° F (–170° C) at night.

Even the most earth-like planet, Mars, strikes fear into the hearts of winter-coat manufacturers: Although the global average temperature on the Red Planet is –81° F (–63° C) it can get as cold as –220° F (–140° C). On the bright side, if you choose your summer vacation spot carefully on Mars, you may enjoy a balmy summer day of 68° F (20° C). That's almost warm enough for sunbathing, although the lack of a natural planetary sunscreen to filter out harmful ultraviolet rays might give you a fatal skin peel, not to mention an all-body case of melanoma.

The lowest low ever recorded on Earth dates to January 23, 1971, when the temperature dropped to –79.8° F (–62° C) at the Prospect Creek Camp in Alaska's Endicott Mountains, 20 miles (36 kilometers) north of the Arctic Circle.  That's pretty darn cold, but I almost hear snickering in the background from Arno Penzias and Robert Wilson, who won the 1978 Nobel Prize in physics for discovering the cosmic microwave background radiation.  "Minus 79.8?" they chortle. "You call THAT cold?"

The microwave hangover from the Big Bang warms the universe to an equivalent of 2.73° Kelvin. That's 2.73° above absolute zero, the point at which molecules freeze in their tracks. And just think: It only took a wind chill of around 250° Kelvin to shut down the Milwaukee Public Schools.

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