Barometers

GHA said:
Have a look here..
http://aprs.fi/
the WX icons are weather stations, many with live pressure readings, you could use local stations to calibrate your units. Assuming there's a button to do so. 1050 sounds a wee bit high...
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That's a nice link. Unfortunately the one thing it doesn't seem to give is the height ASL of the stations. There is a station about 2 miles from me but I think with quite a significant height difference.
 
geoffatstanpit said:
You need QNH

Remember it well! we called it queen nan how! I suppose it's now quebec november hotel. Doesn't roll off the tongue so well somehow!
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From what I've heard, they just call it "Q N H". It's kind of a word on its own, kyooenaich, so doesn't need to be spelled out. Like you don't say "Mike Mike Sierra India" for an MMSI on marine radio.

Pete
 
Sarpath will give you calibrated reading for the nearest (active) airport or harbour in any area in the World.

http://www.starpath.com/barometers/baro_cal.php

Just type in your Lat - Long into the boxes and it give a list of the nearest active airports or barometric stations in your area.

So for Carrickfurgus Marina NI which has a Lat - Long 54° 42.619'N 005° 48.792'W

The first calibrated barometer down the list is Belfast Harbour (54° 36.0´N 005° 52.0´W) 6.9nm away and the current pressure (1728UTC) is 1018.0 mB having risen from 1017mB this morning.



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Confuscius he say, "Man with one clock always know time, man with two clocks never certain."

Synoptic weather maps on the net or even in newspapers are usually good enough. A few Mb out is neither here nor there, it is the changes that count.
You can certainly use QNH from an aviation site but why bother when the Met Office publish the surface pressure chart here?
http://www.metoffice.gov.uk/weather/marine/
 
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Just checked the Metar for Aberdeen, about 14 miles from me. Q=1012. My house is almost exactly on the 100M contour, so should read 11.4Mb less.

Reading is 1001 as near as I can make it within the scale limits, so I'm well chuffed that it's accurate!
 
Thanks for all the replies, sorry for the delay in resounding but have been out of reception in Muck and Moidart. The barometers are going up and down like a yoyo at the moment and we are now holed up in Arisaig. I will reread all the posts and see if I can get access to the required info. I know that ships used to keep 3 chronographs in order to disregard the wildly inaccurate one and split the difference on the others. I know the importance with a barometer is its change but it would be nice if they were at lease partially right.
 
I think Confuscius would say "man with three barometers got too much money". I'd have thought that within 4 or 5 Mb was close enough for on board work - the datum really isn't that important but it would be easy to interpolate the charts to within one or two. Perhaps once it's set it would be of interest to log your barometer performance over a period of time and see how accurately it tracks the changes across the range of highs and lows.

PMG, you're on the 1017 - 1018 isobar in Arisaig right now according to a look between a couple of the the Met Office charts.
 
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prv said:
From what I've heard, they just call it "Q N H". It's kind of a word on its own, kyooenaich, so doesn't need to be spelled out. Like you don't say "Mike Mike Sierra India" for an MMSI on marine radio.

Pete
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Yep it's 'Kew-en-aich', not quebec november-hotel. I was taught to remember it as 'Q Not Here' that is not at the actual airport runway. QFE is 'Kew-eff-ee' as in 'Q Field Elevation'. The Q doesn't actually mean pressure because there were lots of Q codes in morse and Aldis lamp days (possibly still are for nerds) but very few of the Q codes are used nowadays. But every pilot sets QNH and often QFE on every flight.

And remember you don't need to know the elevation of the airfield if you use QNH - it's sea level pressure already. However you do need to do a bit of mental arithmetic if you want to calibrate your barometer at your house that's at a different elevation from the airfield (where pressure is QFE) and not at sea level (presumably above it!).

Some sort of nautical equivalent of VOLMET would be great. The airports are motivated to do recorded weather (called ATIS, rather than VOLMET which is different) because otherwise air traffic controllers have to give out the weather essentials (including wind and QNH) to every aircraft before takeoff and landing and sometimes at other times too, and doing it 'by hand' like they do at quieter airfields would drive them potty at busy ones and clog up the working channels. Where it's recorded it tells you which version you have, rotating round the alphabet, so if I have charlie and the controller thinks I should have delta he knows to bring me up to date. So normal procedure where there is ATIS is on contacting the first controller (perhaps called Nutwood Ground or Nutwood Tower if you're wanting to taxi and take off, or Nutwood Approach, or Nutwood Radar if you are inbound - all working on different frequencies) to make your number, tell him what you'd like to do (like land, or start your engine to taxi) and confirm you have the latest ATIS by adding to the end of your message . . . . 'with charlie (or tango or whatever)'.

By the way it''s E & OE as far as flying information goes because it's some years since I've piloted an aircraft and when I did I was . . . hmmm . . . not very good at it.

You could say in a yacht you don't need the actual pressure - as long as your barometer is consistent, what does it matter if it's consistently 10 millibars higher than actual? What you're interested in is how quickly and how much it's rising and falling. I'm not sure I agree with that as I like to note pressure in the log and it seems a bit barmy to note a pressure that I know is wrong. And how do I know my barometer is consistently wrong without checking it, at which point I might as well set it right.
 
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