Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hello, heres my question....it might seem obvious, but i would like a proper geographical explanation... Why do temperatures fall as altitude increases??

    Thanks!
    Offline

    0
    ReputationRep:
    Not too sure, is it to do with the higher up you go the less shielding ther is from surrounding objects, that may be a factor.
    Offline

    0
    ReputationRep:
    its something to do with the decrease in pressure as you get further up, cant remember right now... will think about it
    Offline

    0
    ReputationRep:
    Isn't it because the sun's rays pass through the atmosphere and the ground absorbs these rays and radiates them as heat. So doesn't it follow that the temperature will be highest closer to the ground than in an area of high altitude?

    But then I'm not totally sure, because wouldn't convection suggest otherwise - that hot air will rise due to it being less dense than the surrounding air and will thus collect largely at the top of a system... :confused:

    Help please, I'm a geographer...but a rather shoddy physicist.
    Offline

    0
    ReputationRep:
    (Original post by mobbdeeprob)
    Isn't it because the sun's rays pass through the atmosphere and the ground absorbs these rays and radiates them as heat. So doesn't it follow that the temperature will be highest closer to the ground than in an area of high altitude?

    But then I'm not totally sure, because wouldn't convection suggest otherwise - that hot air will rise due to it being less dense than the surrounding air and will thus collect largely at the top of a system... :confused:

    Help please, I'm a geographer...but a rather shoddy physicist.
    yeah, basically the primary source for heating of the air is the earth. so as you get higher in the trophoshere (the layer of atmosphere closest to the earth) there is a lapse rate of about 6.5oC per km. it is more complicated but as i dont understand any of the terms.. relates to convective something or other..another thing could be due to the fall in pressure, the gas expanding and therefore cooling as it requires energy to expand.
    (i am not a geographer! and we havn't really covered this in physics!)
    Offline

    0
    ReputationRep:
    ahh kind of got it, the ambient lapse rate is the actual change in temperature on average as you ascend a certain height.

    the adiabatic lapse rate is the change in temperature due to the thinning of the atmosphere, since it becomes less dense, the gases expand and cool due to the energy required to expand. (and because the atmosphere is primarily warmed only by heat radiated from the earth.)

    hope this makes some kind of sense, sure there are a lot of people who could explain it better than this.. any volunteers?
    Offline

    2
    ReputationRep:
    (Original post by slop8)
    Hello, heres my question....it might seem obvious, but i would like a proper geographical explanation... Why do temperatures fall as altitude increases??

    Thanks!
    air is heated from ground below
    Offline

    0
    ReputationRep:
    (Original post by FaerieLand)
    ahh kind of got it, the ambient lapse rate is the actual change in temperature on average as you ascend a certain height.

    the adiabatic lapse rate is the change in temperature due to the thinning of the atmosphere, since it becomes less dense, the gases expand and cool due to the energy required to expand. (and because the atmosphere is primarily warmed only by heat radiated from the earth.)

    hope this makes some kind of sense, sure there are a lot of people who could explain it better than this.. any volunteers?
    I understand (the middle part), because the Earth is a closed system full of gas etc. There will therefore be more pressure on something close to the surface of the Earth than in the troposhere (because there will be loads of air piled on top of it from above).

    Therefore, the less dense air at altitude will expand - because gases expand to fill the surrounding space. As you rightly say, this expansion will expend energy and also become less dense, cooler and fall to the ground (convection).
    Offline

    2
    ReputationRep:
    It is not the case that (very simply - GCSE level only):

    The air is heated from the ground (which is in turn heated from the sun).

    And that this acts as a raditator to the atmosphere and air around.

    The higher you go. The less land there is to heat the air (imagine tip of mountain), therefore less particles are heated and the air is cooler.

    I have learnt that: You go down by -10 Degrees C for every 1000m you go above sea level.
    Offline

    0
    ReputationRep:
    (Original post by TheWolf)
    air is heated from ground below
    How efficient is the transfer of heat from the ground to the top of the troposphere?
    Offline

    2
    ReputationRep:
    (Original post by mobbdeeprob)
    How efficient is the transfer of heat from the ground to the top of the troposphere?
    Quite good. By Radiation and then Convection.

    Anyway the point is that it isn't very good, hence colder then higher you go.
    • Thread Starter
    Offline

    0
    ReputationRep:
    Thanks guys for the info! From what youve told me i would say, in a nutshell, that air is less dense as it rises, therefore it loses heat. Is this correct? Have i understod it properly?
    Offline

    0
    ReputationRep:
    i dont rekon convection currents have nethin 2 do with it..hot air rises

    i think the windchill factor will affect the temp, although i do no that the lower the angle of the sun, the greater the amount of atmosphere through which the rays will have to pass. so..heat will be lost due to gases, dust and cloud in the atmosphere.
    hope it makes sense!
    Offline

    0
    ReputationRep:
    (Original post by neha p)
    i dont rekon convection currents have nethin 2 do with it..hot air rises

    i think the windchill factor will affect the temp, although i do no that the lower the angle of the sun, the greater the amount of atmosphere through which the rays will have to pass. so..heat will be lost due to gases, dust and cloud in the atmosphere.
    hope it makes sense!
    Of course convection has 'something to do with it', how would we get convectional cloud systems otherwise? Granted, in a simple GCSE response you don't need to mention it, but it would be foolish to think that convection played no part in temperatures at altitude.
 
 
 
Poll
Do you like carrot cake?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.