Why do barometers have different centre readings? I thought 1000 mbar was average, as that's what barometers always used to have as the central reading ("change"), but Wikipedia says it's 1013. I've seen some newer ones with 1010 as the centre.
Barometers and average pressure
Feb 06, 2020
33 Replies
In space the average is 0 mbar
The same as the pressure between your ears.
On mine it's 29.5 inches
Barometers tend to be used on the ground.
So how come the bar was taken to be slightly different to mean sea level pressure? Was it measured inaccurately when they invented it?
A bar is not defined as 1 atmosphere (average) pressure. Just happens to be close (within 1% of it).
1 bar is equivalent to 100 kPa where 1 Pa (Pascal) is a defined SI unit pressure of 1 Newton per m2.
Phwoar! ;-)
All mine have both measurements. It would appear it should be corrected for altitude, but that would mean a rotatable dial. I've got an app on my phone that does it, it'll be interesting to see if it changes the centre position with altitude, 1010 mbar is about right for here.
So pot luck or something inaccurate in the past? The history of it sounds interesting.
Religious folk would say this was a 1% error made by god :-) So he isn't infallible!
Or an adjustment screw on the back for an aneroid barometer or a moveable linear scale on a mercury one. About 50 mb of adjustment needed here.
Maybe seal levels are dropping ;-)
I am sure Greta would say the air is heavier because of the CO2.
We use mm/hg
Too many clubs.
Oh those poor plants having an easier time breathing now we've unlocked the CO2 that used to be in the air anyway!
Why do you deliberately make the maths more difficult? Use stuff with multiples of 10.
Yes it could be easily done. Although.... should it be done? If you're at a higher altitude, you have lower pressure, but you also have more cloud. Clouds tend to hang around mountains.
That is metric. What did you have in mind?
Many measurments have changed over the years. The standard meter or foot or some length was changed not long ago and it was enough that the US east to west coast changed by almost 20 feet.
Metric.
Wouldn't you get that much by sea erosion anyway?
Dial? My barometer is a column of mercury.
Cindy Hamilton
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