Bars and millibars are metric (1 bar or 1000 mb equal one atmosphere. SI changed to Pascal as the unit of pressure, you choose the prefix to suit the value, aircraft use hPa because it’s the same number of digits as millibars, but kPa is fine for most atmospheric pressure, this is what the Canadians use for weather reports on TV. Over here in France (and I believe the rest of Europe including the UK) they use hPa for weather reports.
An interesting aside, I was driving back from the airport the other day and passed a line of Army Land Rovers, I thought they were probably French, but passing one I saw stencilled on the spare tire holder 60 PSI, so I figured they must be British, although I would have thought the British military were entirely SI by now. Mike Payne On 30 Jun 2014, at 06:51, cont...@metricpioneer.com wrote: > While customizing my http://www.TimeAndDate.com preferences today, I became > rather curious about why so many options are available for Pressure Unit. I > see on the list millibar, Hg, Pa, bars, mmHg, psi, atm and kPa. Now, since I > know less about Pressure Units than most of you, I am hoping someone would > jump in and recommend the most appropriate one. (I already know that none of > you will recommend psi.) Thanks in advance. See attached picture. I hope none > of your computers have trouble opening a png picture format. > > David Pearl www.MetricPioneer.com 503-428-4917 > <Pressure Unit.png>
