On Thu, 06 Feb 2020 14:37:11 -0000, "Commander Kinsey"
wrote:

On Thu, 06 Feb 2020 14:11:13 -0000, Andy Bennet wrote:

On 06/02/2020 14:00, Commander Kinsey wrote:
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.

In space the average is 0 mbar

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?

Maybe seal levels are dropping ;-)

I am sure Greta would say the air is heavier because of the CO2.