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Thread: Two questions about arctic areas

  1. #1 Two questions about arctic areas 
    Forum Junior anticorncob28's Avatar
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    1) I have heard that it never snows in Antarctica (very, very rarely actually). The snow that does fall, never melts.
    What if it did actually snow frequently in Antarctica? I guess that every water molecule on earth would eventually get to that area, and it would snow and never melt. So Antarctica would be building up enormous ice and eventually taking up all the water in the world.
    2) If Pangaea was located mostly in the arctic or antarctic areas (say the center of it was in the north or south pole), how would that have affected the evolution of life on earth up to today?
    I wonder about this.


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  3. #2  
    Forum Cosmic Wizard
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    1) "What if" can be fun questions to think about. If all the water was getting locked up in a polar ice sheet I think it would eventually get to the point it would stop doing it.

    Try not to waste too much time thinking about this one.
    2) Our ancestors would have been much hairier than we are.


    Last edited by dan hunter; February 22nd, 2014 at 07:30 PM. Reason: white space correction
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  4. #3  
    Forum Professor jrmonroe's Avatar
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    Snow and ice sublimate, which explains the shrinking ice cubes in an unused ice tray.

    sublimate
    v.
    to cause to change directly from a solid to a gas, or from a gas to a solid, without becoming a liquid
    Grief is the price we pay for love. (CM Parkes) Our postillion has been struck by lightning. (Unknown) War is always the choice of the chosen who will not have to fight. (Bono) The years tell much what the days never knew. (RW Emerson) Reality is not always probable, or likely. (JL Borges)
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  5. #4  
    Moderator Moderator Janus's Avatar
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    To answer your first question, it snows an average of 6 in. a year in Antarctica. But is it not quite true that it never melts. The its sheer weight compresses and pushes the ice sheet out to the Ice shelves which float on the ocean. Ice breaks off these shelves forming ice bergs which float into warmer waters and melt. The snow that does fall in Antarctica is slowly returned to the ocean.

    So, if it snowed more in Antarctica, this would be offset by faster growth in the ice shelves until the iceberg formation once again balanced things out.
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  6. #5  
    Universal Mind John Galt's Avatar
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    The volume of sea water is approximately 13 billion cubic kilometeres. The area of Antarctica is approximately 14 millions square kilometres. Ignoring compression the snow would have to be almost 100 kilometres high on the continent to empty the oceans. It is obvious why that would be impossible, so the hypothetical problem - like the snow - evaporates1.


    1. I am well aware that snow does not evaporate, but - as jrmonroe has pointed out - it sublimes. However, I insist upon misusing the words because of the elegance of the resulting phrase2.

    2. Some of you will rightly point out that it is still ridiculous to talk about evaporation of snow. All that means is that we are going from the sublime to the ridiculous.
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    The sublimation rate would be proportional to the surface area. If you just piled the snow higher and deeper, that wouldn't increase the surface area, so I agree with the iceberg explanation.
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  8. #7  
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    Quote Originally Posted by Harold14370 View Post
    The sublimation rate would be proportional to the surface area. If you just piled the snow higher and deeper, that wouldn't increase the surface area, so I agree with the iceberg explanation.
    But the relative scarcity of H2O molecules outside the icemass would change the vapour pressure differential and that should limit the process.

    You would also soon hit the point where the weight of the ice would be more than the bearing strength of the ice and it would yield. It would creep outwards to escape the pressure and the surface area would increase.
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  9. #8  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by dan hunter View Post
    Quote Originally Posted by Harold14370 View Post
    The sublimation rate would be proportional to the surface area. If you just piled the snow higher and deeper, that wouldn't increase the surface area, so I agree with the iceberg explanation.
    But the relative scarcity of H2O molecules outside the icemass would change the vapour pressure differential and that should limit the process.
    Surely if there is less moisture in the atmosphere that should increase the sublimation rate.
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  10. #9  
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    Quote Originally Posted by John Galt View Post
    Surely if there is less moisture in the atmosphere that should increase the sublimation rate.
    I thought that was obvious, but yes, and that should limit the process of ice accumulation.

    Sorry if I tend to be too brief in my comments.
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  11. #10  
    Universal Mind John Galt's Avatar
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    Yes, brevity in this case created a grammatical flow in which sublimation was the process. Thank you for clarifying. (I like brevity, but I also like precision, )
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  12. #11  
    Forum Junior anticorncob28's Avatar
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    So, does anybody else have anything to say about my second question?
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  13. #12  
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    2) If Pangaea was located mostly in the arctic or antarctic areas (say the center of it was in the north or south pole), how would that have affected the evolution of life on earth up to today?
    I wonder about this.
    Pangaea could not possibly have been located "mostly" at either of the poles. Just look at the relative sizes of those areas versus the continents you're thinking of.



    The World 57,308,738 Sq. Miles (148,429,000 Sq. Km) 100%
    Asia (including the Middle East) 17,212,000 Sq. Miles (44,579,000 Sq. Km) 30.0%
    Africa 11,608,000 Sq. Miles (30,065,000 Sq. Km) 20.3%
    North America 9,365,000 Sq. Miles (24,256,000 Sq. Km) 16.3%
    South America 6,880,000 Sq. Miles (17,819,000 Sq. Km) 12.0%
    Antarctica 5,100,000 Sq. Miles (13,209,000 Sq. Km) 8.9%
    Europe 3,837,000 Sq. Miles (9,938,000 Sq. Km) 6.7%
    Australia (plus Oceania) 2,968,000 Sq. Miles (7,687,000 Sq. Km) 5.2%


    The 4 largest land masses add up to 78% of the total land mass, while Antarctica is less than 9%. The Arctic Ocean is much the same size as Antarctica, barely 5 & 1/2 million sq miles. So it also is equivalent to about 9% of the total land mass.

    The best comparison for these purposes is North America. Large parts of Canada and Alaska are within the Arctic circle, above 66 degrees of latitude. While Mexico City is a mere 19 degrees of latitude above the equator.

    Quite enough scope for evolution of just about anything and everything from polar bears to tropical frogs.
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  14. #13  
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    Most of the Antarctic ice is not moving towards the sea at all, but simply accumulated to such a high elevation that the air is too cold and thin to hold water vapor sufficient for snowfall. If there is mass escaping from the center of the cap it's probably mostly from melting and sub-ice river systems near the bottom.
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  15. #14  
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    Central Antarctica also has high winds that cause erosion.

    http://www.amnh.org/education/resour...tic_winds.html
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  16. #15  
    Forum Junior anticorncob28's Avatar
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    Thanks for your response. I actually suspected that was the case, adelady. So, if the center of gravity of pangaea was located at the north or south pole, the super-continent would have been large enough so the coast would be 30 degrees away from the equator, or even closer. So the most extreme thing is that everything living in the center of pangaea was arctic animals and life, and as you got closer to the coast, the climate was warmer and was represented so by the life. That actually sounds quite neat. Makes me kind of wish that was true. Is that what you meant by "Quite enough scope for evolution of just about anything and everything from polar bears to tropical frogs. "?
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  17. #16  
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    Is that what you meant by "Quite enough scope for evolution of just about anything and everything from polar bears to tropical frogs. "?
    Near enough.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  18. #17  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    One mus also consider the Permian climate, which was in general warming from the end Carboniferou s iceage, and which resulted in warming and drying of the Pangean interior. https://en.wikipedia.org/wiki/Permian#Climate
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  19. #18  
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    The continental crusts are (most likely) constantly growing at the expense of the oceanic crust. So, comparing pangea to the present continents is a bit of a stretch.
    true?
    (literally and figuratively)
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  20. #19  
    Forum Radioactive Isotope Paleoichneum's Avatar
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    Not true. You are forgetting the major influence of erosion on continental mass.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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  21. #20  
    Forum Junior anticorncob28's Avatar
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    Whether the total land mass was higher or lower back then doesn't matter much; it is clear that Pangaea was far too large to be located mostly in an arctic region.
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  22. #21  
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    Climate systems are generally more complex than that. For instance, one immediate problem with an entirely ice-covered supercontinent is that there are a severely limited number of viable carbon sinks, so over relatively short periods of time the climate will warm to the point where the ice melts.

    Remember that there have been a number of times throughout geological time when there was no ice at the poles.
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  23. #22  
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    Quote Originally Posted by drowsy turtle View Post
    Remember that there have been a number of times throughout geological time when there was no ice at the poles.
    Even during cold periods there is still meltwater under the ice because the earth itself generates heat too.
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    Quote Originally Posted by John Galt View Post
    we are going from the sublime to the ridiculous.
    Groan.
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