Why are the top of mountains cold?

Discussion in 'Earth Science' started by John Connellan, Oct 23, 2009.

  1. kira Valued Senior Member

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    I believe that spidergoat post (post #2) is correct:

    There was similar thread about this, but I can't figure it out where. Something is hot or cold is depend on the heat (which represent the amount of energy), but not necessarily the temperature. Do you recall some heat formula, such as in definition of latent heat or sensible heat? Heat is a function of mass (and hence density), too. So, up in the mountain is colder because the air density is fewer. As what is explained by Spidergoat earlier.
     
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    John, you are exhibiting a lot of miss understanding (and probably have never been tossed around in an airplane at 30,000 + feet by rapidly rising air, as part I made bold of your text text above is wrong)

    I suggest you read my post 13 until you can understand it. It corrects your prior error in detail. You have a very false idea about the importance of the surface heating of high altitude air - it is insignificant without the vertical mixing (vertical movements of air masses) I described in post 13 as then only conduction (thru air which is a very poor conductor of heat by pure conduction) and radiative transfer are available to transfer heat vertically.

    If you can not understand part of post 13 I will respond to any question you hav on what it teaches.
     
    Last edited by a moderator: Oct 26, 2009
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  5. John Connellan Valued Senior Member

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    A lot? I thought u said nearly all of my previous post was correct? Why the sudden change?

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    Actually no, not a lot at 30,000 feet. Tended to happen a lot lower than that for me.

    I understood what you were saying before about the wet ALR.

    From where did you get this idea? Isn't my whole point (from the very first post) that the reason mountain tops are cold is because the surface heating of air at high altitudes is insignificant? Are you not reading my posts properly?

    I dont understand where you are going with this point. Please explain.
     
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  7. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    You're just playing word games here.

    We aren't talking about "the higher levels of the troposphere." We're talking about mountains, which are - by definition - in the planetary boundary layer, where vertical mixing is very strong. As anyone who'se ever spent much time on mountains can easily discern.

    The upper levels of the troposphere - by contrast - are approaching the stratosphere, where vertical mixing is poor and temperature increases with altitude. But that's neither here nor there when it comes to the temperature on mountains.
     
  8. John Connellan Valued Senior Member

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    You're the one playing word games with the below so don't start that:



    I was just correcting you.


    Anyway, I am not disputing that vertical mixing occurrs in the atmosphere, just that it has nothing to do with my point.

    Take inner siberia for example. Mountains there will be cold and that fact that it is cold is not directly a result of the air pressure atop the mountain. it is cold because it is further from the heated surface. Also, any covection trying to occur will soon stop because the dry ALR will mean that a warm air parcel will soon reach the temperature and density of the surrounding air long before the top of some high mountains.

    We can ignore any wet ALR processes in Siberia due to the very low moisture content.
     
  9. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Because you now have added this nonsense: "there is not much vertical air movement"
    Yes, the vertical momentum of air is less at 30,000 feet than at the top of mountains, but some strong tropical thunder heads even reach that high, so it is nonsense to say, as you did,: "there is not much vertical air movement" at mountain tops.
    Good. Does that now include fact you were wrong to say: "the parcel is often even colder than the surrounding air." as I explain due to the effect of H2O vapor condensing it is actually warmer and accelerating upward. ??

    Also at any altitude the pressure in adjacent air masses is essentially the same. Thus, if one were colder it, it is denser and would sink to a lower altitude EVEN IF THERE WERE NO WATER VAPOR IN IT. - Another reason why what you stated is false / nonsense.
    You spoke of upper air being heated from the ground AND also falsely claimed: "there is not much vertical air movement" I was only pointing out how totally self contradictory you were being.

    Convection which is overwhelmingly the most important heat transport mechanism in air and ceases to exist with your "there is not much vertical air movement." Then there is only conduction and radiation to move heat upwards. The top of mountains would be much colder than they are without convection helping the sun to heat them.
     
    Last edited by a moderator: Oct 27, 2009
  10. iceaura Valued Senior Member

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    The mountain top is a heated surface - with less barrier air above it, it is more strongly heated by the sun than the lower surfaces.
     
  11. John99 Banned Banned

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    i don think so.

    and they dont retain the heat. the distance from the mountain top to the ground is not a significant factor. so heat loss due to distance between them is not an issue. too many other things to consider.
     
  12. John Connellan Valued Senior Member

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    Well i am still right in saying there is not as much as there is lower down nearer the surface. At the tops of high mountains, vertical mixing occurs much less than at the lower slopes. That's all I was saying. Anyway all of this is off topic. The point is, the parcel does not contribute to the cooling of the upper air (or warming for that matter).

    I am still right though. there are not that many stratospheric thunderclouds around the world when looking at the bigger picture. We're talking about the average climate of a mountain top here. But I can see you're point that there are probably many thermal clouds other than thunderclouds which can reach to mountain hights of 5000m or 6000m.

    Air ascending at the dry adiabatic lapse rate is also warmer than the surrounding air. Water vapor is irrelevent! But I am not wrong. Parcels of air are often forced up sides of mountains where they can adiabatically cool to a temperature lower than the surrounding atmosphere. Sort of like a natural refrigerator.

    It might seems like nonsese to you at first but you are overlooking many simple things like my point above.

    How many times do I have to repeat myself? Look what I asked just a few posts ago:

    And why didn't you answer this question anyway?

    I said in the upper troposhere.
     
  13. John Connellan Valued Senior Member

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    This is true. There is more radiation energy per square foot. However, how many square feet do you have?

    Think about it.
     
  14. John99 Banned Banned

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    that is another factor.
     
  15. John Connellan Valued Senior Member

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    It's not the distance to the sun he is talking about. It is the thickness of atmosphere above your head.
     
  16. John99 Banned Banned

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    no it isnt above my head.

    why is the atmosphere thick? you know humidity creates thick air.
     
  17. iceaura Valued Senior Member

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    Depends on the mountain. Many are large and flat an top ("mesas").

    The Tibetan plateau is measured in square miles.
     
  18. John99 Banned Banned

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    mountains are primarily hard surfaces that is one factor. another is that there is no water on the mountains especially saturated ground or lakes.
     
  19. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    Have you ever been to a mountain before?
     
  20. iceaura Valued Senior Member

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    ? Of course it is. Climb one and find out - very strong sunlight at high altitudes.

    There are many high altitude lakes on this planet, and they are in general much colder than the low atlitude lakes in the same region.

    Despite absorbing more solar energy from stronger sunlight.
     
  21. John99 Banned Banned

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    iceaur, the base of the lakes is hard rock. there are no trees. one thing where there is some contention is in deserts.
     
  22. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    There are plenty of mountains that are treed all the way to the top, which still exhibit the predicted temperature decreases with altitude.

    Example
     
  23. iceaura Valued Senior Member

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    I am not familiar with places where the "base of the lakes" is trees. The base of the lake nearest me is rock. Nevertheless, it is warm in the summer sun. Crater Lake is not as warm in summer, despite being in stronger sunlight. Crater Lake is of course surrounded by trees, but the shade of trees rather cools than warms any nearby water: http://en.wikipedia.org/wiki/File:Crater_Lake_National_Park_Oregon.jpg
     

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