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$1$atm $= 101325$pa
$1$bar $= 100000$ pa
$1$atm $= 1.013$ bar
$1$bar $= 0.987$atm

From wiki:

The bar is a metric (but not SI) unit of pressure exactly equal to $100000$ Pa.[1] It is about equal to the atmospheric pressure on Earth at sea level. Atmospheric pressure is the pressure exerted by the weight of air in the atmosphere.

My question: I presume ground level is higher than sea level. #Why is the pressure at sea level Less than at ground level?# I thought that since sea level is at a lower level, there will be a greater weight of air and hence higher pressure on it compared to at ground level

my correction. I am sorry. Why is the pressure at sea level =1bar Less than at ground level=1atm, when supposedly there would be more air hence a greater weight of air hence a higher pressure?

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    $\begingroup$ I'm not sure I understand the question - a bar is roughly one atmosphere (standard), which makes it a kind-of useful unit. Where is the ground level vs sea level coming from? $\endgroup$ – Jon Custer Dec 14 '15 at 19:00
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    $\begingroup$ @Boomzxc - You are reading too much into that snippet from wikipedia. We happen to like powers of ten, and 100000 is about equal to 101325. That's all there is to it. $\endgroup$ – David Hammen Dec 15 '15 at 10:27
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As David has mentioned, you are interpreting too much into the value 101'325 Pa. This is an average pressure which can change quite a lot depending on the weather. E.g. if you are in a low pressure system, the sea level pressure can be far bellow 100'000 Pa, If the local weather is a high pressure system, it will be much higher than 101'325 Pa.

Of course you are right: ground level pressure is usually lower than sea level pressure.

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Why is the pressure at sea level greater than at ground level?

Most of the time, sea level is below ground level.

So, most of the time, you're at a higher elevation than sea level, and the column of air above you will weigh less than it does at sea level.

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  • $\begingroup$ Then, why is it that the pressure at ground level(101325pa) is greater than that of sea level(100000pa)? $\endgroup$ – Boomzxc Dec 15 '15 at 5:37

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