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Venus atmosphere pressure

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#1 k.s.min

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Posted 28 January 2020 - 03:18 PM

l,m  studing  gravity.

 

Venus'  surface   atmosphere  pressure  is  known  as  200  atm.

Earth  has   1 atm pressure.

 

The  2  planets'  density, mass, size  are  almost  same.

Gravitational  force  affecting  to  each  air  molecular   is  propotional  to  the  planet's  mass.

 

then,  why  the  2  planets  have  so  different  air-grasp- abilities?

Our  Earth  also  can  grasp  such  an  huge  specific  amount  air-mass    making  200atm(200kgf/cm squre) ....if  human  would  prouce  enough  CO2  gas? 



#2 Stellar1

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Posted 28 January 2020 - 04:03 PM

Well, im going to give this the olde college try, the atmosphere on venus, (whatever molecules present) are in a much higher concentration than earths atmosphere. i imagine venus's atmosphere is dense

enough that if you had a scale to measure atmospheric density, 1 being earths, and 100 being the density of water, Venus's atmosphere is so heavy that it would feel like being under water, all that matter would exert a pressure much higher than here on earth.

 

Now, as for air grasp capabilities, it would be tempting to ponder that but, venus, being much closer to the sun, has vented off much more trapped gasses than earth has. What im trying to say is, even though

both planets may have equal gravitational power to hold their atmospheres, Venus has off gassed into its atmosphere a lot quicker, given millions of years maybe Venus is slowly equalizing to an atmosphere

closer to earths pressure.

 

Someone may shoot me down but, i tried and my daddy would be proud i say! 


Edited by Stellar1, 28 January 2020 - 04:04 PM.


#3 StarBurger

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Posted 28 January 2020 - 04:55 PM

It's a matter of the escape velocities of the atmospheric constituents and chemistry.

Both Venus and Earth have similar surface gravities and hold on to similar gases in the same way. Once those gases are present in their atmospheres there is no major mechanism apart from EXTREME heat ( causing the molecules to exceed escape velocity) or chemical reactions ( by locking up the gases in the surface rocks) that can reduce the atmosphere.

Mercury is just too hot to hang on to any atmosphere.

Venus was born with a heavy CO 2 atmosphere and little of it has been lost.

Earth probably had a similar CO 2  load but it has been locked up in the surface rocks, the oceans and in plant life which Venus does not have.

Mars, with its low escape velocity, has a thin CO 2 atmosphere due to its low gravity allowing most of its original atmosphere to bleed into space.

If our poor Earths atmosphere continues to accumulate CO 2 it will simply continue to do so until we have unlocked all the carbon in the rocks and oceans and then we will start to look like Venus!

It's not an "air grasp'" difference. Both planets are the same.Both hold on to CO 2 the same way.

The difference is in the initial CO 2 present and the way in which the CO 2 has been removed from the atmosphere.

Another effect is temperature of course. Venus being closer to the Sun and hotter will tend to loose the lighter gases more than CO 2, hence the higher concentration.

CO 2 is a "heavy" gas and tends to stick around.

It is all a little more complex than this when we have to consider the effect of UV light and other processes on the evolution of an atmosphere, but gravity is not the important aspect.


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#4 sg6

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Posted 28 January 2020 - 05:05 PM

Now, as for air grasp capabilities, it would be tempting to ponder that but, venus, being much closer to the sun, has vented off much more trapped gasses than earth has. What im trying to say is, even though

both planets may have equal gravitational power to hold their atmospheres, Venus has off gassed into its atmosphere a lot quicker, given millions of years maybe Venus is slowly equalizing to an atmosphere

closer to earths pressure.

I would have suggested that Venus being closer to the sun has lost a greater degree of the lighter gasses that were originally present.

 

So over time the Earth would also lose more of it's proportoion of the lighter gasses and so we would tend towards Venus, rather then Venus tending towards Earth.

 

Unsure of the core of Venus and if it has a magnetic field, but being closer the solar wind will have plucked away at the lighter gasses, if they were in free form and not as part of a heavier mollecule.

 

Being hotter it seems reasonable that whatever gasses are present have sufficent energy to bond into heavy molecules also. Oxygen is fairly reactive and I would suspect that with higher ambient temperatures it cannot exist as O2, so rapidly forms CO2 and H2SO4.



#5 llanitedave

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Posted 28 January 2020 - 07:32 PM

Earth probably had a similar CO 2  load but it has been locked up in the surface rocks, the oceans and in plant life which Venus does not have.


This is the big ingredient.  Earth stores much of its carbon it its rocks and biomass, Venus stores it in the atmosphere.

 

Venus has no limestone.  Earth's crust has huge volumes of it.



#6 VeloBob

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Posted 05 February 2020 - 10:05 AM

One other thing--Venus has remnants visible that suggest the largest amount of vulcanism known.  On earth, CO2 is one of the main ingredients of volcanic eruptions.  So not only did Venus not get the advantage of life, it probably had the disadvantage of having much more CO2 added by its period of intense volcanic activity. 




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