Understanding the effects of gravity on a gas

In summary, according to the second law of thermodynamics, the pressure at the top of a gas container will be less than the pressure at the bottom due to the effects of gravity. This lack of pressure at the top is due to the random motion of the gas molecules and is not related to the temperature gradient.
  • #1
striphe
125
1
If a gas is enclosed in an insulated container on earth, I understand that at the top of the container there will be less pressure than at the bottom due to gravity.

What I want to know is if the top is colder due to the effects of gravity. If reliable sources could provided it would be appreciated (I can't seem to find any).
 
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  • #3
Can you go into it any more than just simply 'no' curl, as to why?
 
  • #4
The kinetic theory of gases describes the atoms or molecules of a confined gas as having a random distribution of the x,y and z components of velocity, and they move in straight lines until they collide with the container walls and bounce off. That description leads to a mixing that would have the population of molecules in any region of the container having the same average kinetic energy as the molecules in any other region of the container.

To produce the difference in pressure between the top and bottom due to gravity, change the reference to motion in straight lines into a reference to motion in parabolas that are very nearly straight lines. This makes the density and pressure slightly less at the top. Whether that causes a slight temperature gradient, I don't remember.
 
  • #5
Curl said:
Wrong. The answer is yes. First off, Wikipedia is not a reliable source, and secondly that wiki article doesn't say anything about the question being asked.

Lots of people go to the mountains in the summer to escape the heat. Think about that for a second.

Google the phrase "lapse rate".
 
  • #6
Mikelepore, My own consideration of what occurs within the gas regarding a possible heat difference; that heat is related to the kinetic energy of the molecules that make up the gas, with that kinetic energy being converted to gravitational potential energy if a molecule moves against the force of gravity.

D H, Curl may have read my other thread, "the altitude hypothesis" which brings about a particular dilemma based on this. The thread eventually came to a halt when I asked about lapse rate.

The hypothesis has two parts and what i was expecting was that the latter part to be the shortcoming. The users that posted opted for the first part as being the problem. That being a heat gradient does not emerge in contained body of gas under gravitational force.
 

1. How does gravity affect the behavior of gas particles?

Gravity plays a crucial role in the behavior of gas particles as it is responsible for the attractive force between particles. This force causes the particles to come closer together, resulting in a decrease in volume and an increase in pressure.

2. Can gravity change the state of a gas?

Yes, gravity can change the state of a gas. If the gravitational force is strong enough, it can cause the gas to condense into a liquid or solid state. This is why gas giants like Jupiter have a dense, solid core despite being composed mostly of gas.

3. How does gravity affect the movement of gas particles?

Gravity affects the movement of gas particles by pulling them towards the center of the Earth. This results in random movements of particles, known as Brownian motion, which is responsible for the dispersion of gases in the atmosphere.

4. Does gravity have the same effect on all types of gases?

Yes, gravity has the same effect on all types of gases regardless of their chemical composition or physical properties. However, the magnitude of the effect may vary depending on the mass and density of the gas particles.

5. How does gravity affect the pressure of a gas?

Gravity affects the pressure of a gas by compressing the gas particles closer together, which increases the number of collisions between particles and the walls of the container. This results in an increase in pressure, as explained by the Ideal Gas Law.

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