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Why is high in the sky not warmer as it's nearer the sun


FUNder

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I'm a total newbie to the fascinating subject of meteorology so bear with me my ignorance and total lack of education on the subject.

 

The sun is powerful enough to heat the ground on the earth. If you go into space and travel towards the sun you'd need a thicker heat shield the nearer you got to it. 

 

On a sunny day you are warm walking around at street level, if you go to the top of a building or to the top of a high hill it's even hotter - fitting in with being nearer the sun.

 

So, why is it so cold the higher up you go in the atmosphere, shouldn't it be hotter?

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The atmosphere is what retains the heat. The higher you go up, the thinner the atmosphere is, and the less heat it is capable of holding in. If you go to a hill or the top floor of a building, it is hotter. The atmosphere goes up a long way, so just going up a few floors of a building, or a steep hill isn't going to effect the atmospheres ability to retain the heat very much, and heat does rise. If you go to the top of a mountain or something however, the atmosphere is so much thinner that any heat there isn't isn't kept in as effectively as it would be where the atmosphere is thicker, and therefore it is considerably cooler.

There may be other factors involved in why it is cooler when you go up, but this one seemed like the main one to me. I hope this helps. :)

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Posted
  • Location: Portlethen - Aberdeenshire
  • Location: Portlethen - Aberdeenshire

    Whats stranger is that the earth is actually closer to the Sun in winter than in summer...

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    Posted
  • Location: N.Bedfordshire, E.Northamptonshire
  • Weather Preferences: Cool not cold, warm not hot. No strong Wind.
  • Location: N.Bedfordshire, E.Northamptonshire

    That and as I understand it the heat is what is reflected from the surface, to put it in simple terms.

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    Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL

    <quote>On a sunny day you are warm walking around at street level, if you go to the top of a building or to the top of a high hill it's even hotter - fitting in with being nearer the sun.</quote>

     

    This is not true. Temperature decreases with height (up to a point), so the top of a hill is not warmer than the bottom except in very specialized circumstances.

     

    The atmosphere is largely transparent to the incoming short-wave solar radiation, so the Sun does not heat the air around you directly. The surface absorbs the incoming SW radiation and emits long-wave IR radiation which does lead to heating of the air around you. 

     

    The distance from the Sun doesn't really matter, it is insolation that is important, which is why it's cold in the NH hemisphere winter even when the Earth is closest to the Sun.

     

    http://en.wikipedia.org/wiki/Insolation

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    Posted
  • Location: Evesham, Worcs, Albion
  • Location: Evesham, Worcs, Albion

    Actually, just to confuse things, although it starts off getting colder as you climb higher, it then gets warmer for a time ......and then gets colder once more before it then then warms up even more:  such that the warmest part of the atmosphere is actually the thermosphere, over 100km up, where it gets much hotter than it does on the Earth's surface..... Only out into the exosphere does it then finally cool off again as you move out into space .....

    Posted Image

     

    For a good explanation , see:
     

    http://www.windows2universe.org/earth/Atmosphere/layers_activity_print.html

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    Posted
  • Location: N.Bedfordshire, E.Northamptonshire
  • Weather Preferences: Cool not cold, warm not hot. No strong Wind.
  • Location: N.Bedfordshire, E.Northamptonshire

    I think absorbed by the surface and then re-radiated at different wave lengths. It's reflected by ice and snow, etc leading to the albedo discussion.

    Yes quite right, think the heat is getting to me (doh!)

     

    This includes some simple explanations of things

     

    (biiiiiiig picture)

     

    http://www.livescience.com/29572-earth-atmosphere-layers-atmospheric-pressure-infographic.html

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    Posted
  • Location: Dulwich Hill, Sydney, Australia
  • Weather Preferences: Hot and dry or cold and snowy, but please not mild and rainy!
  • Location: Dulwich Hill, Sydney, Australia

    Yes radiative strength gets weaker as you go further from the sun, basically according to an inverse square law,the intensity drops off as 1/r^2.

     

    However when you look at the difference in radiative strength between the top of the atmosphere and the bottom there is barely any difference because the atmospheric thickness (approximately 100kms) is so small compared with the earth's distance from the sun (150 million kms) which if you calculate that is something like a 0.00001% differnence. So basically we can regard this as constant, and the closeness to the sun is essentially irrelevant to how warm it is.  

     

    The difference is about where that incoming radiation is absorbed. While the atmosphere absorbs some radiation most of the radiation absorbtion occurs at the surface of the planet, there fore this is the warmest and heat generally rises up through re-radiation or convection into cooler temperatures. However there are other region of absorbtion, and for example ozone in the stratosphere causes rising temperatures as you go up as shown in the picture in Essans comment

     

    Also note the very high temps in the Thermosphere shown in that graph while correct are misleading - as while what gas there is is highly energetic (which is the definition of temperature) its essentially a vacuum and not "warm" as such. A traditional thermometer for example would measure muhc lower temperatures (below zero) as it would radiate faster than it could absorb energy from the gas.

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    Posted
  • Location: Camborne
  • Location: Camborne

     

    Also note the very high temps in the Thermosphere shown in that graph while correct are misleading - as while what gas there is is highly energetic (which is the definition of temperature) its essentially a vacuum and not "warm" as such. A traditional thermometer for example would measure muhc lower temperatures (below zero) as it would radiate faster than it could absorb energy from the gas.

     

    More or less correct.

     

    Above the mesopause, atmospheric densities are extremely low, although the tenuous atmosphere still effects drag on space vehicles above 250 km. The lower portion of the thermosphere is composed mainly of nitrogen (N2) and oxygen in molecular (02) and atomic (0) forms, whereas above 200 km atomic oxygen predominates over nitrogen (N2 and N). Temperatures rise with height, owing to the absorption of extreme ultraviolet radiation (0.125-0.205 um) by molecular and atomic oxygen, probably approaching 800-1,200 K at 350 km, but these temperatures are essentially theoretical. For example, artificial satellites do not acquire such temperatures because of the rarefied air. 'Temperatures' in the upper thermosphere and exosphere undergo wide diurnal and seasonal variations. They are higher by day and are also higher during a sunspot maximum, although the changes are only represented in varying velocities of the sparse air molecules.

    atraunauts

     

    In a sense the solar wind is similar to this. It reaches supersonic velocities but atraunauts don't get blown away.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    Whats stranger is that the earth is actually closer to the Sun in winter than in summer...

     

    For the NH yes. But during our winter the SH is having its summer.

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    Posted
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 :-)

    Good point CC, Probably that's why the South Pole is so much colder than the North Pole, But then again the South Pole is more than 9,000 feet in elevation.

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    Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

    Air is a very poor conductor of heat, so sunlight just passes through the atmosphere without heating it a great deal. However, the ground absorbs a lot of that light and heat. This then radiates heat out, warming the air above. Obviously, as you get further away from the ground, it will be less influenced by the warmer ground, so it gets cooler with height.

     

    The sudden spike in temperature in the stratosphere is due to the ozone layer absorbing UV radiation.

     

    At very high altitudes, temperature is a bit of a tricky concept as it fundamentally relies on the presence of air. But with the atmosphere being of such low density at high altitudes, this definition isn't very fulfilled.

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    Posted
  • Location: Shrewsbury
  • Location: Shrewsbury

    What is it about Britain though that 200m of altitude can make such a difference? Everywhere else I've been it's more like 500-1000m before you start to notice a different type of climate, for instance in the Mediterranean. 

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    Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

    What is it about Britain though that 200m of altitude can make such a difference? Everywhere else I've been it's more like 500-1000m before you start to notice a different type of climate, for instance in the Mediterranean. 

     

    Not sure if it is the case or not, but if it is I would imagine it's because there is greater surface heating at lower latitudes.

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