Low pressure

[Clive]

I know it's not calibrated but that's the lowest I've ever seen it go, but at least it's back on the rise now.

 

[+Ibbo]

My weather station recorded about 28" but I reckon the outside temp was a bit off at 60°C

 

[philjay]

My barameter is showing 958mbar at tge mo, never seen it this low either.Its almost off scale any lower and it l bend the pointer

[+Bino-viewer]

Can you explain what '30' denotes and 28 please ?

I'm guessing some old imperial measurement ?

 

I thought they generally used millibars on barometres ?

[philjay]

Heres mine

[philjay]

8 minutes ago, Bino-viewer said:

Can you explain what '30' denotes and 28 please ?

I'm guessing some old imperial measurement ?

 

I thought they generally used millibars on barometres ?

Inches mercury. 28 is about 980 millibar

Edited November 2, 2023 by philjay

[Clive]

20 minutes ago, Bino-viewer said:

...I thought they generally used millibars on barometres ?

We still use pints and miles as units of measure in the UK so I've no problem with inches of mercury 😆

[+Bino-viewer]

Thanks for the explanation.

 958 mb is very low, isn't it ?

 

It's been a day of records.

Lowest UK barometric pressure reading (at sea level, in England & Wales during November)

occurred today in Plymouth at 953.3 mb. The previous low during November occurred in 1916.

 

The all time record UK low occurred over central Scotland on January 26, 1884 at 925.6 mb

 

Looking at world records lows, you have to venture into the eye of tropical hurricanes, cyclones and typhoons.

A reading of 870 mb was recorded inside the eye of Typhoon Tip, which hit the western Pacific area on 12 October 1979

 

 

But even lower pressures can be found inside tornados, which is why you hear people recounting that their ears 'pop'

if they've had an encounter with a tornado. I don't think these pressures are routinely measured though, and the other record lows

are all listed as 'non tornadic'

 

All fascinating stuff......

 

 

 

 

 

 

 

[+Ibbo]

 

About a million years ago when I worked at Orgreave Coke ovens we had to calibrate the thermometers for 2 reasons I can remember one being to calc the calorific valve of the gas we prduced and also the salting point of the napthalene.

 

Anyway we had a proper barometer that was actual mercury and was in a lovely case , one or 2 of the staff had to get a box to stand on to read it.

 

28" is about 948mb if google is correct.

Edited November 2, 2023 by Ibbo

[+Bino-viewer]

According to Siri (on my iPhone) the current reading in Derby is 968.32 mb so it looks like its gone up a touch.

[+Bino-viewer]

For those of us who are mountaineers.....

 

The lowest tolerable pressure of air is about 0.47 atm (475 millibars of atmospheric pressure) - recorded at 5950m altitude. At about 0.35 atm (less than 356 millibars at around 8000m) life is impossible. Pulmonary and cerebral edema lead to death.

 

 

[philjay]

The inches mercury originates from the stick barometers which had a glass tube filled with mercury with an inch scale next to it.

As pressure changed you read the value from the scale adjacent to the meniscus.

[Clive]

In a few years prior to retiring I worked for a company that amongst it product line were pressure sensors, both standard of the shelf and bespoke models.  Even the of the shelf models were offered with options for 17 different units of pressure measurement.