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Terrestrial atmospheric pressure and density
by
cube
on 07 Mar, 2022 23:44
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Hello, I know that at sea level the hotter it is the less dense the air is, but in this same situation would the air also have a lower barometric pressure because of the heat?
In some videos they explain that air pressure can be visualized as the weight of a column of air above a certain surface so I guess in my situation even though the air is less dense (dilated ) there is always the same amount of air above the ground so there is the same pressure at sea level regardless of the temperature.
Is my guess correct?
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#1
by
Jim
on 08 Mar, 2022 00:25
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They both are interrelated. And no, the height of the atmosphere fluctuates
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#2
by
Nomadd
on 08 Mar, 2022 00:35
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Hello, I know that at sea level the hotter it is the less dense the air is, but in this same situation would the air also have a lower barometric pressure because of the heat?
In some videos they explain that air pressure can be visualized as the weight of a column of air above a certain surface so I guess in my situation even though the air is less dense (dilated ) there is always the same amount of air above the ground so there is the same pressure at sea level regardless of the temperature.
Is my guess correct?
Think about it again. Barometers would never change if that was true. Since different temps mean different densities, there isn't always the same amount of air in an particular column. Some videos over simplify things. Air moving also affects barometric pressure by creating density variations..
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#3
by
cube
on 09 Mar, 2022 12:55
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So if one increases the other automatically increases and vice versa
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#4
by
Barley
on 10 Mar, 2022 19:05
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You can answer the question empirically by looking at weather reports. You will find both cold high pressure areas (air mass comes from the arctic) and warm high pressure areas (air mass comes from the tropics).
In some places in winter high pressure areas are usually associated with cold temperatures. A cold core high may hold records for both highest surface pressure and lowest surface temperature in some areas.
The atmosphere is not in equilibrium, is three dimensional, and water changing state must be considered.
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#5
by
cube
on 25 Mar, 2022 21:14
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There is something that seems a little strange to me, there was a solar flare which caused a magnetic storm which caused the starlink satellites to re-enter, if I understood correctly during this storm the upper atmosphere slightly warmed and this would increase the density of the atmosphere (and drag) where the starlink satellites were, but the warmer air is assumed to be less dense, i'm slightly confused.
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#6
by
Nomadd
on 26 Mar, 2022 02:36
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There is something that seems a little strange to me, there was a solar flare which caused a magnetic storm which caused the starlink satellites to re-enter, if I understood correctly during this storm the upper atmosphere slightly warmed and this would increase the density of the atmosphere (and drag) where the starlink satellites were, but the warmer air is assumed to be less dense, i'm slightly confused.
There was more air where the sats were because the increased temperature from the solar storm caused the atmosphere to expand. Average density from the ground up decreased. Think of gravity constrained air as sort of a non linear pressure balloon.
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#7
by
cube
on 26 Mar, 2022 18:16
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Thank you, I hadn't realized that it was the global density (and pressure) of the atmosphere (whether at sea level or at 10km altitude) that had decreased compared to normal.
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#8
by
Jim
on 27 Mar, 2022 13:52
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Thank you, I hadn't realized that it was the global density (and pressure) of the atmosphere (whether at sea level or at 10km altitude) that had decreased compared to normal.
pressure doesn't change at sea level, the same amount of air is in the column. It is less dense but it is also higher.
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#9
by
cube
on 27 Mar, 2022 14:12
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But if the density is different does this not mean that the quantity of air in a certain column of air will be different (so different pressure) as said above?
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#10
by
Jim
on 28 Mar, 2022 16:47
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But if the density is different does this not mean that the quantity of air in a certain column of air will be different (so different pressure) as said above?
No, the "volume" of air expands (higher) too. The total amount of air is fixed for the purpose of this discussion.