Measurement of atmospheric pressure

Tyeeking

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Anyone who wants to know the weather conditions.

I mean, why is the barometric pressure shown in the daily weather report?
But who really pays attention to the barometric pressure in the daily weather report? The average user who wants to know how the weather is going to be for golf, fishing, painting the house doesn’t care about that and the more serious weather observer already understands the various units of measurements as they are used today.
 

Charles_McG

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And here I thought that 1 Bar and 1 Atm were both meant to define a typical condition- just not the [exact] same one. A little like I need to keep an eye on whether an sccm is defined at 0°C or 20°C
 

MetricRocketeer

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But who really pays attention to the barometric pressure in the daily weather report? The average user who wants to know how the weather is going to be for golf, fishing, painting the house doesn’t care about that ...
Perhaps you are correct on that issue.

I am just wondering, however, whether barometric pressure -- if it is going to be reported -- should be reported in atmospheres.
 

Charles_McG

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Perhaps you are correct on that issue.

I am just wondering, however, whether barometric pressure -- if it is going to be reported -- should be reported in atmospheres.
-Should- will always depend on the audience. Apparently European weather maps are drawn in hectopascal and millibar is an American thing.

Technical communities will always pick units that make for easy math and have values that are 1-3 digits, mostly to the left of the decimal. Hence medical people express thing in mg/dL and wineries use g/hL (except when I'm feeling weird and use g/gal - but that's only because 1 g/gal of K2S2O5 yields ~150ppm SO2. Another case of make the math easy.)
 

Marc_G

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Just a thought: when barometric pressure is reported locally, in inches of mercury, it is usually adjusted for altitude versus sea level and reported as relative pressure. I've never seen this done with millibar units. Hurricane reporting is (I think) always done with sea level measurements. Thus, perhaps the use of millibar in reporting is to remove ambiguity as to whether the pressure is absolute or relative, as a convention.

Again, I'm not an expert in any of this.
 

heada

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Fisherman certainly pay attention to air pressure. The air pressure and to a larger extent, pressure waves, effect feeding habits of fish. Its not uncommon to see increased number of fishing boats just before a storm rolls in.

Want to know who uses air pressure the most, and why it'd be such a huge effort to change? Airplanes. Every time a plane is cleared in for landing, ATC gives them the local air pressure at ground level. Pilots then adjust their instruments to compensate. If they're off too much they slam into the ground.
 

MetricRocketeer

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For instance, Fahrenheit is vastly superior to Celsius when trying to measure body temp or ambient air temp, because it has a larger range, and can be more precise without resorting to more significant digits. But if you want to boil or freeze water, at 1 atmosphere of pressure only of course, and the water is pure and has no salts in it, then…well…Celsius is the way to go! Never mind that no other substance has melting and boiling points that easy to remember. We should definitely choose our everyday temperature system based on the phase change points of water at standard atmospheric pressure. :rolleyes:
I prefer to measure temperature using a system where water freezes at 0 degrees and boils at 100 degrees.
 

smstachwick

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Normal atmospheric pressure at sea level measures 29.92 inHg, rounding to two decimal places. Wait! What? Who can remember this?
Me!

I will probably never be able to un-remember the robotic-sounding voices in Microsoft Flight Simulator 2004/X saying “altimeter two niner-niner two” in the many times I flew in fully standard conditions.
 

Steve Shannon

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I prefer to measure temperature using a system where water freezes at 0 degrees and boils at 100 degrees.
There’s nothing wrong with that, but understand that it’s a personal preference. Other people have other preferences. Some might even insist that a temperature range based on absolute zero is more correct. Any other zero is somewhat arbitrary.
None is actually superior. They’re just different views of the same property.
 

smstachwick

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I prefer to measure temperature using a system where water freezes at 0 degrees and boils at 100 degrees.
Imperial isn’t that difficult to work with either, especially in regards to everyday temperature. I think of it a bit like a percentage. Most people are ok in the 70s% range, below that ranges from cool to really cold, above that ranges from warm to too hot for comfort. Out of the scale means some truly uncomfortable extremes indeed.
 
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