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Day after tomorrow: Can an ice age occur overnight?

  1. Sep 24, 2011 #1
    I just watched a day after tomorrow for the first time today, am I really hit me. Can A ice age occur overnight?
     
    Last edited by a moderator: Sep 24, 2011
  2. jcsd
  3. Sep 24, 2011 #2
  4. Sep 24, 2011 #3

    cmb

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    The second part of the question doesn't make much sense, because we are in an ice age right now!

    We just happen to be in an interglacial period, where the climate is, errr..., unpredictable and jumps up and down randomly a little!

    At the end of the Quaternary Ice Age we are in, if it is much as previous ice ages the temperatures will shoot up and the CO2 concentration will follow (not like this piddling little interglaicial we are in now, but 1,000's ppm CO2 and +10C) as the flora and fauna proliferates and accelerates the carbon cycles. Well, this is what looks to have happened before, after other ice ages like the one we are in now.

    We're currently in an interglacial that started around 12k years ago. There have been several such cycles of glacial/inter-glacials during this ice age, covering the last ~700k years. It looks like we are determinedly set to enter further glaciations before this ice age finishes.

    The other inference of your question, a point I found cringeworthy in the film, is the idea that just because the air temperature is at -150 so everything instantly freezes up. Nice for the story line I suppose, but I guess the script writers hadn't considered the thermal inertia of air (very low) versus a lump of helicopter (very high). I guess it would begin to struggle, but I doubt if a helicopter that flew straight into a -150 air mass would not have time to land safely.
     
    Last edited: Sep 24, 2011
  5. Sep 24, 2011 #4

    rude man

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    It can if you live in Ottawa, Canada in the winter! I did. (Now I'm in Phoenix, AZ where we already recorded 122F in the summer.)
     
  6. Sep 27, 2011 #5
    Even if a radical event happens that ejects millions of tons a debris into the atmosphere and blocks out the sun it would take months or even years before their is a large global cooling.
     
  7. Sep 27, 2011 #6

    D H

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    That depends on what you mean by "overnight". To a climatologist or geologist, the answer is "yes". They just have a different concept of what overnight means than do the rest of us. To a geologist, "overnight" means hundreds of thousands of years. Thousands of years is not just overnight to a geologist, it is a blink of the eye. Climatologists have learned that the climate can sometimes switch modes "overnight" -- where overnight means several years to a century or more.

    As for the movie you watched: It's just a study in how badly the media can mangle science.
     
  8. Sep 27, 2011 #7

    AlephZero

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    A small amount of icing on the rotor blades would be enough to cause big problems by screwing up the aerodynamics of the blades. That could well happen in a timescale of minutes. Aircraft anti-icing systems aren't designed to deal with temperatures as extreme as that. Even commercial jets cruising at 35,000 ft are only operating in temperatures of about -50 to -70C (-60 to -100F).

    If the rotor blades aren't aerodynamic any more, you can't even do an autogyro style engine-out landing.
     
  9. Sep 28, 2011 #8
    I cringed when the air from the upper troposphere instantly froze people - apparently -64F is nough to do that :rolleyes:.
     
  10. Sep 28, 2011 #9

    D H

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    I cringed when the air from the upper troposphere rushed down so rapidly that it had no choice but to stay ultra cold. Apparently the writers hadn't heard of adiabatic heating. Or maybe they did.



    Here's what really happens when air from the upper atmosphere for various reasons plunges toward the surface:

    Witchita, Kansas June 6, 2011 heat burst
    http://www.accuweather.com/blogs/weathermatrix/story/50816/wichita-heat-burst-last-night.asp

    A National Temperature Record at Loma, Montana
    http://ams.confex.com/ams/annual2003/techprogram/paper_54387.htm

    Downbursts such as these (heat burst, Witchita; Chinook wind, Loma) don't always make the local temperature hotter. If the incoming air is cold enough aloft it can still be colder than the air it replaces when it hits the ground. Sometimes the Santa Anna winds make LA get hot and dry, sometimes cool and dry. However, you'll never see air moving so fast that it forgets the laws of physics.
     
    Last edited: Sep 28, 2011
  11. Sep 28, 2011 #10

    cmb

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    Yes, at higher temperatures.

    But the plot of the film is a body of air with very low temperatures - at temperatures too low to carry water vapour to freeze. Air is very dry at such low temperatures.

    In parts of Russia, the ambient can drop below -70C. At that temperature, your breath freezes instantly and falls to the ground as ice, you can hear it crackling as it freeezes and drops out of the air.

    So the plot line of the film is reasonable - so long as the helicopter is being breathed on by a flying giant at the same time.... which is, perhaps, not so unreasonable, given the rest of the film :devil:

    We could argue that this cold air mixes with some lower air carrying humidity, and you get some sort of mix that results in a freezing fog.... but.... do we have to!!?!?

    Film-goers associate 'cold' with a layer of ice. That's the only reason it was put in the film like that. I'd guess the first risk would be waxing of the fuel, so if it was really bad enough to do anything, engine power would be lost and they execute an autorotation, promptly.
     
  12. Sep 28, 2011 #11
    If you go here to slide 8 you'll see that the practical minimum temperature to get(light) icing is -40C while moderate to severe icing can only occur normally between 0 and -20C.


    Right thou must be joking. I have seen the thermometer at -63C in Resolute Bay in Canada February 1989 and not a trace of such an event. But there were other interesting things to do with cooking water.

    Mark Twain
     
  13. Sep 28, 2011 #12

    D H

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    http://www.islandnet.com/~see/weather/events/life-80.htm
    The freezing of one's breath produced a continuous hissing sound similar to dry blowing snow, and a tinkle when the ice crystals hit the ground. ​

    One of my office mates (a few offices down the hall, actually) wintered over at the Amundsen–Scott South Pole Station. He reports a similar phenomenon, only he described it as sounding almost like a jet engine. Not nearly as loud as a jet engine, but a very similar roar. Then again, that was -95 F rather than a balmy -70. (He never did make it into the 300 Club. They had a mild winter that year. It only dipped below -100 F for a few minutes that year, not long enough to fire up the sauna.)
     
  14. Sep 29, 2011 #13

    cmb

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    Wikipedia says; "The lowest temperature ever recorded at the surface of the Earth was −89.2 °C (−128.6 °F; 184.0 K) at the Russian Vostok Station in Antarctica July 21, 1983."

    There is a deep valley somewhere in Siberia (if I recall where, I'll post it) where cold air collects and, partially hidden by the Sun, the temperature is routinely -78C (I'm talking 'C' here), so presumably some of the snow might include solid CO2 there?
     
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