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Comment on If hot air rises, why is it colder at the top of a mountain?

Without checking, I would say that it’s because the heat dissipate away from the planet and the hot air will eventually cool down while rising? My understanding is that it’s hot near sea level because it’s where the heat from the sun get reflected and radiated from the earth surface, correct me if I’m wrong…

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JudahBenHur@lemm.ee ⁨2⁩ ⁨months⁩ ago
if you don’t know, don’t bother writing anything

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- mattreb@feddit.it ⁨2⁩ ⁨months⁩ ago
  Sorry i didn’t meant to be misleading, just to discuss! However after checking on Wikipedia en.m.wikipedia.org/wiki/Lapse_rate I omitted that lower pressure air at high altitude absorb/emit less heat, but what I wrote is not wrong, just incomplete…
  
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  - JudahBenHur@lemm.ee ⁨2⁩ ⁨months⁩ ago
    ✌️
    
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milicent_bystandr@lemm.ee ⁨2⁩ ⁨months⁩ ago
I believe it’s less about heat dissipation than about adiabatic expansion - where air as it expands does ‘work’ and loses heat.

The heat coming (as far as the air is concerned) mainly from the ground sounds like a good point, but IIRC the temperature at altitude follows the expected curve for adiabatic expansion given the pressure change, so I think that heat-entry-point-effect must be much less significant except close to the ground.

Come to think of it, most heat loss from the earth must be from infra red, which will also come from the opaque ground much more than from the air.

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- mattreb@feddit.it ⁨2⁩ ⁨months⁩ ago
  Yeah “dissipate away” is probably a bit misleading but I meant that the heat source is mainly the surface since it’s difficult to heat the thin outer layers directly, and from there heat moves up thorough ir radiation or adiabatic expansion. But it’s not like mountains are cooled down by adiabatic expansion, since the air wouldn’t move up without a temperature gradient, which means that it cannot get colder that the mountains already are. So I would think they are simply farther away form surface heat radiation and have thinner air that don’t assorb heat…
  
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  - milicent_bystandr@lemm.ee ⁨2⁩ ⁨months⁩ ago
    
    which means that it cannot get colder that the mountains already are
    
    Absolutely it can. That’s the adiabatic expansion: air gets colder precisely by expanding against other air. No mountain needed.
    
    As to solar absorbtion, the mountain is a good point: the sun is actually incredibly strong on mountains, because less air above is absorbing light, meaning, I think, you’ve actually got more intense surface heating at the top of a mountain, unless there’s snow to reflect the heat.
    
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