Why is atmospheric pressure the same indoors?

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Discussion Overview

The discussion revolves around the concept of atmospheric pressure and why it remains consistent indoors despite the presence of a ceiling. Participants explore the nature of atmospheric pressure as a state function and its dependence on elevation, as well as the implications of having a ceiling above them.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why atmospheric pressure does not change indoors, given that there is a ceiling above them, suggesting that pressure is a state function dependent on elevation.
  • Another participant introduces a hypothetical scenario of pumping air out of a house to illustrate the concept of air pressure and questions what prevents air from entering through cracks if the house is airtight.
  • A different participant proposes that atmospheric pressure can be better understood as a density gradient of air, with the highest density at ground level.
  • Some participants express confusion regarding the explanation of atmospheric pressure as a column of air extending miles above, noting that this seems more applicable to outdoor scenarios.
  • One participant reiterates the idea that atmospheric pressure is due to air molecules pressing down, but acknowledges that this explanation feels more relevant when outdoors.

Areas of Agreement / Disagreement

Participants express varying levels of confusion and differing interpretations regarding the nature of atmospheric pressure indoors. There is no consensus on a singular explanation, and multiple viewpoints are presented.

Contextual Notes

Some limitations in the discussion include assumptions about the airtightness of structures and the implications of pressure being a state function. The discussion does not resolve these assumptions or the complexities involved in understanding atmospheric pressure indoors.

mcmath
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Hi, apologies in advance as I feel stupid for asking this, but believe me I tried googling. The typical explanation for atmospheric pressure is that there is a column of air sitting on us, creating a pressure of 101 kPa. But what if there's a ceiling above us? Now only a few feet of molecules is directly above our heads. Why doesn't atmospheric pressure change? I remember vaguely from a physics course that it's related to pressure being a state function only dependent on elevation, and that pressure is applied in all directions at the given elevation. So I can understand that my arms may feel the 101 kpa pressure, but if I'm indoors, why does the top of my head still feel the same 101 kpa pressure?
 
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mcmath said:
The typical explanation for atmospheric pressure is that there is a column of air sitting on us, creating a pressure of 101 kPa. But what if there's a ceiling above us? Now only a few feet of molecules is directly above our heads. Why doesn't atmospheric pressure change?
Imagine you pumped all the air out of your house. Is your house air tight? What keeps the air from pouring off the roof of your house and in through the cracks between your front door and its frame?
 
ok, so I guess a better explanation of atmospheric pressure is that there is a density gradient of air, with the density being heaviest at ground level?
 
I guess my main point of confusion is when people explain atmospheric pressure to me as a column of air above our heads, extending miles into the air, which would mean the 101kPa pressure is from the billions of air molecules pressing down on my head, which makes sense only if you're outdoors
 
mcmath said:
I guess my main point of confusion is when people explain atmospheric pressure to me as a column of air above our heads, extending miles into the air, which would mean the 101kPa pressure is from the billions of air molecules pressing down on my head, which makes sense only if you're outdoors

Well, this column likes to seep through any tiny crack and push in from all sides.
 

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