Why is it colder at higher altitudes?

21 February 2010

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Question

I was told that, the closer one is to the sun the hotter it is. So why is it that, the higher the altitude one is at, the colder it is?

Answer

Well, the reason, Dennis, is if you think about it, the distance between the Earth and Sun is a very long way. It's a hundred million miles or so. And therefore, the distance between the Earth's surface and the top of Everest at 29,000 feet is a tiny fraction of the total distance to the Sun: in the grand scheme of things, it's a trivial change in the actual distance. So that isn't why the temperature changes and therefore also why it isn't hotter.

The reason it's actually colder is because, as you go up in the atmosphere, the Earth's atmosphere feels less pressure the higher up you go. So as the gas in the atmosphere rises it feels less pressure, which makes it expand. When the gas expands it does some work. And and if it's doing work, it must be losing some energy; and if it loses energy, its temperature must drop because we define temperature as the average energy of the particles. Therefore, if the energy of the particles is lower, the temperature must be lower.

That's why, at altitude, the temperature appears to fall. In space, outside the earth's atmosphere, if you're facing the Sun, you can actually fry. That's why space suits are specially designed in order to keep people from getting too hot in the sunny bits but also prevent them from becoming too cold in the non-sunny bits.

Comments

Mountains are cooler than other places

Upward radiation from the atmosphere at lower altitudes is largely absorbed by the atmosphere at higher altitude and subsequently reradiated downward. As one goes higher this is less true and more of the radiation
escapes into interplanetary space. This makes the higher altitudes colder. The radiation is electromagnetic (photons) in the infrared part of the spectrum.
It is true that rising air cools, but this does not apply to the steady state of the atmosphere.

With increasing altitude, temperature falls; it reaches a minimum at about 15-20km, then begins to rise again. The drop is because the air expands and cools the atmosphere. The rise is because, beyond a certain point, UV is no longer attenuated by the ozone layer and conditions warm up again.

Technically temps should rise above 32 degrees Fahrenheit roughly up 200k ft ...well before we reach the moon

If cold air is more denser than hot air it means it's mass is heavier than hot air than it should flow on earth surface

Good explanation

its the atmosphere that makes it colder

Due to gravitational pull maxim.gas particle remains near earth surface.so when we go upward atmospheric pressure is low.

Bloody great answer! Thank you!

Why is this article written so unintelligently?
The pressure feels less? No the pressure can't feel anything the atmospheric pressure is less.

It's valid English to write that, and it's also true; the atmosphere - meaning the gas molecules therein - "feel" less pressure at higher altitude.

In this explanation, perhaps "feels" was selected as a poor choice of words to describe that at higher altitudes, gases expand because as high space is approached by lighter gas particles they spread out due to the vacuum in higher altitudes. Gases don't actually have tactile feeling and thus feels less pressure per se...but it's one way to explain what happen to heated gas molecules in their expanded state rising and cool differential to heavier heated molecules staying close to the surface of Earth, trapping moisture molecules in the process which is another matter entirely. Snowbirds appreciate heat humidity. Now figure out why dry ice vapors sink. Is it possible that cabon dioxide is in vapor form heavier than the air we breathe?

Wait hold up, doesn’t hot air rise so why isn’t all the hot air going up If there is also less pressure higher up?

The lower density of hot air means that convection carries it aloft continuously, just as smoke rises up a chimney. The steady warming of air close to the ground replenishes the warm air lost upwards by heating the cooler air that flows in to replace it. This establishes a steady cycle of rising warm air and in-coming cooler air.

I’m trying to do my homework

Why do people get sun burns at different rates

Because it depends on peoples stupididty

The amount of melanin in the skin determines how quickly one sun burns. The darker your skin the slower you burn. Melanin absorbs sunlight like the color black represents little to no light energy reflecting back from the observed object depending on how deep the black is.

An object with total or near 100% light absorption is considered perfect black and the eye at that point can't even make out 3d dimensions.

Consider a red object is red light reflecting back while the other colors are absorbed.

I'm not satisfied. At what distance shall become hot once again?

I don’t know that there is anything to be unsatisfied about lol. The temperature will start slowly increasing when there is no longer a significant change in pressure, and you decrease the distance between the object in question and the sun.

why is it increasing if we go up in to the mountains then decrease in the top?

Actually as we are climbing high we are going close to the sun but why is that it gets cooler

Perhaps try reading the answer above...?

Interestingly enough the time of year that is the hottest for us is when the earth is furthest from the sun.

On summer days, you go to the mountainous range or plain terrain. Only then the pilot of plane tells that the outside temperature is -40 ° C, while you are close to the sun and still you feel cold.

Why there is less pressure in the high altitudes???

Because you are further from the center of the earths gravitational pull (Which creates a force, and hence the pressure)

The height of the atmosphere - at tens of kilometres - is negligible in comparison with the distance from the centre of the Earth to the planet's surface (6000 kilometres). Certainly gravity plays a role - without it there would be nothing to hold on to the atmosphere, but it is the mass of the atmosphere itself that exerts the pressure at ground level. As you ascend in the atmosphere there is less atmosphere above you and hence less force / pressure.

Mass does not exert a pressure, force does. The mass of the atmosphere above a given point on or above Earth's surface (think a column or area A of air particles above that point that is within Earth's gravitational pull) times the standard acceleration due to gravity, g, which equals about 9.8 m/s^2, gives you the force. Divide that force by area A to get a value for pressure.

Thanks. U Are True Scientist. I Agree With U.

Pressure = Force/Area = mass*acceleration/Area = mass*acceleration from gravity/Area =m*g/A

It is both the mass of the atmosphere and the acceleration due to gravity that results in atmospheric pressure, to the first approximation.

Why does well water feel cold in summar, while warmer in winter?

I agree with Chris here, its the mass of atmosphere that is majorly changing, the 'g' is more or less constant.

density is changing which result in a change of mass.
pressure = density * g * h
g = acceleration from gravity
h = height

Gravity does change. Gravity at the equator is actually less than closer to either of the poles. This is caused by increased centripetal acceleration which acts in the opposite direction to gravity. As the altitude increases the distance to the centre of the earth increases, reducing the gravity, and the centripetal acceleration increases, reducing the gravity further, but the stuff about atmosphere is true

this is in relation to the higher you go the cooler it becomes. Assuming global warming is increasing as science has it, does this mean that water vapor will fail to condense at some point in time?

That's very unlikely to happen. Global warming considers ground surface temperatures and the changes that are being predicted are of the order of a few degrees. Unless we enter a runaway greenhouse state like Venus, which doesn't seem likely at the moment, water will still condense.

So if I had 2 clear boxes, one with low pressure air and one with high pressure air, after a few hours the one with high pressure air would be warmer than the one at low pressure? assuming they are well insulated

The important take-home point here is that the rising air is "doing work" against the atmosphere as it expands. When something "does work" then it must consume energy. Something with a lower average energy will have a lower temperature. 

Air in a sealed box is not doing work because it is at a constant volume; therefore its temperature remains constant. But if the air is allowed to escape and expand - for instance like air issuing from a pressurised cylinder - then it will produce a drop in temperature as it expands.

what make the air to expand, when it escape

The answer given is the correct one. Perhaps you should research a topic a little more before making pronouncements like the one below that serves only to show how little you do actually know... What has been said in answer to this query is quite right.

To echo the thought posted below in hopefully a less condescending tone, I thought that any pressure allowed to sit for a time would eventually average out to a "room temperature" of sorts. I was under the impression that high altitudes were cooler because of distance from the surface (or whatever is absorbing most of the suns heat), which was why depths in the ocean are cooler despite their higher pressure. This however does not account for cold air on a mountain top on a calm day, so I'm looking for a better explanation.

I think you're right. The reason why it's colder the higher you go is because there is less atmosphere around you to contain energy/heat.

hahaha...dumb answer above. The sun energy per unit surface is the same, this is correct, but the air is already thin at high elevations and is not expanding anymore to drop the temperature. Try again.

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