Lately, we have been having some gale-force conditions here in So. Calif. I decided that I was going to assume my typical anal self and wanted to see if my barometer was accurate. I emailed NOAA and they said to contact the local Coast Guard. We have a CG station in Corona del Mar, next to Newport Beach, and I called. A young sounding guy answered and said he would "go down to the boat" and get a reading. He called back and said it was 28.63! My barometer was reading about 29.5. I double checked and he said this was his reading. Then, I radioed our Harbor Dept which is directly next door to the CG. Their's said 30.25. At the time, the day was clear, no clouds and light wind. No way was it 28.63. Our nearest airport is about 5 miles inland which would be different that at sea level. Does anyone have a suggestion how I can get my barometer calibrated? Thanks, John Richard s/v Jack's Place
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Bill O'Donovan
Me too
I paid $99 to West Marine and mine is goofy too. West said to compare it to the Weather Channel, and it's showing 30.3 vs. 30.0. That's closer but still imprecise. Be curious to see what response you get.
I paid $99 to West Marine and mine is goofy too. West said to compare it to the Weather Channel, and it's showing 30.3 vs. 30.0. That's closer but still imprecise. Be curious to see what response you get.
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Les Andersen
Barometers
John, Look up the following link, it has more than you ever wanted to know about barometers and calibration. Looks like the easiest way would be to take your barometer to the CG office and set it there using the adjustment in the back. I think that if it is a Weems
John, Look up the following link, it has more than you ever wanted to know about barometers and calibration. Looks like the easiest way would be to take your barometer to the CG office and set it there using the adjustment in the back. I think that if it is a Weems
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Tim Schaaf
Very Easy
It is very easy to adjust your barometer, and the best source of information is an airport. They need to know airpressure, not just for weather, but to calibrate altimeters, so they are usually spot on. They also can factor in altitude. If I were you, I would take my barometer to the nearest airport. You need to do this from time to time, as they don't stay calibrated, for ever, as you will see from how easy it is to move the adjusting screw! But, as a previous post mentioned, the most important thing is the trend, not the actual pressure. Good Luck.
It is very easy to adjust your barometer, and the best source of information is an airport. They need to know airpressure, not just for weather, but to calibrate altimeters, so they are usually spot on. They also can factor in altitude. If I were you, I would take my barometer to the nearest airport. You need to do this from time to time, as they don't stay calibrated, for ever, as you will see from how easy it is to move the adjusting screw! But, as a previous post mentioned, the most important thing is the trend, not the actual pressure. Good Luck.
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Mike Lobenberg
Barometers calibration
I was in West Marine the other day looking at their Barometers. They had 5 or 6, and no two had anywhere near the same reading. The spread was much like your findings in southern California. I guess the barometer readings are somewhat relative, and you are looking for falling or rising conditions. The closest Airport probably has the most accurate readings, but altimeters are set each time you take off which gives you your altitude reference. In school, we made a barometer with a tube sealed at one end and filled with mercury. The tube was inverted (open end down) and placed in a bowl of mercury, then measured the column of mercury within the tube. This will give you an accurate measurement.
I was in West Marine the other day looking at their Barometers. They had 5 or 6, and no two had anywhere near the same reading. The spread was much like your findings in southern California. I guess the barometer readings are somewhat relative, and you are looking for falling or rising conditions. The closest Airport probably has the most accurate readings, but altimeters are set each time you take off which gives you your altitude reference. In school, we made a barometer with a tube sealed at one end and filled with mercury. The tube was inverted (open end down) and placed in a bowl of mercury, then measured the column of mercury within the tube. This will give you an accurate measurement.
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Tom Pfleeger
Use airport barometric pressure
Set your barometer to the reading at your airport (the one only 5 miles away). The barometers at airports are adjusted to take into account their elevation i.e. they are set for sea level. If you take your barometer inland and up in elevation it will have to be reset otherwise you are just reading change in elevation (then its called an altimeter).
Set your barometer to the reading at your airport (the one only 5 miles away). The barometers at airports are adjusted to take into account their elevation i.e. they are set for sea level. If you take your barometer inland and up in elevation it will have to be reset otherwise you are just reading change in elevation (then its called an altimeter).
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Nick
Follow that Low . . .
Unless you are at sea and trying to get into and follow a particular pressure contour the ticks matter little. Set the pointer or note the reading and if she goes up (over several hourly readings) it's an indication of higher pressure and fair WX. Usually . . . Nick "Julia Bell" C-27 #86
Unless you are at sea and trying to get into and follow a particular pressure contour the ticks matter little. Set the pointer or note the reading and if she goes up (over several hourly readings) it's an indication of higher pressure and fair WX. Usually . . . Nick "Julia Bell" C-27 #86
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Dave McCarthy
Weather Radio for Barometric Pressure
I am sure that the airport readings would be most correct. But the transport of the instrument to and from the site could jar and change the calibration. I have used the weather radio and bouy reports from all around my area. When all stations are reporting similar readings, (within a few points) I set my instrument to an appropriate average. I choose a day where there is little 'weather' happening in the area so there is a better chance of being as 'correct' as possible. As pointed out in other replys, the true value of the instrument is in tracking trends, so absolute accuracy is not necessary. Fair Winds, Dave
I am sure that the airport readings would be most correct. But the transport of the instrument to and from the site could jar and change the calibration. I have used the weather radio and bouy reports from all around my area. When all stations are reporting similar readings, (within a few points) I set my instrument to an appropriate average. I choose a day where there is little 'weather' happening in the area so there is a better chance of being as 'correct' as possible. As pointed out in other replys, the true value of the instrument is in tracking trends, so absolute accuracy is not necessary. Fair Winds, Dave
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Andy Howard
Try this Link
It gives current conditions almost all airports in the country. I adjusted mine using an airport several miles inland. Like an earlier poster said, It's not what your baromoter reads so much as the direction it's moving. To HP: My W
It gives current conditions almost all airports in the country. I adjusted mine using an airport several miles inland. Like an earlier poster said, It's not what your baromoter reads so much as the direction it's moving. To HP: My W
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Rich
To calibrate an aneroid barometer
Assuming you have an adjustable, aneroid barometer, there are two approaches to calibrate it in the U.S.: 1. Take it to a manned, official National Weather Service observation site which has a calibrated barometer. Set the device next to the NWS barometer. Adjust your barometer's reading to match the NWS reading. 2. Determine the precise elevation of your barometer above sea level. (This is not a trivial thing to do.) Obtain the sea level pressure reading from a nearby, calibrated NWS observation site. The site needs to be nearby because pressure varies in the horizontal direction. Based on the elevation of your barometer, determine the pressure offset to be added/subtracted to the NWS reading. (This involves applying a simple equation.) Apply the offset to the NWS reading and adjust your barometer to match this final number. I recommend the first approach.
Assuming you have an adjustable, aneroid barometer, there are two approaches to calibrate it in the U.S.: 1. Take it to a manned, official National Weather Service observation site which has a calibrated barometer. Set the device next to the NWS barometer. Adjust your barometer's reading to match the NWS reading. 2. Determine the precise elevation of your barometer above sea level. (This is not a trivial thing to do.) Obtain the sea level pressure reading from a nearby, calibrated NWS observation site. The site needs to be nearby because pressure varies in the horizontal direction. Based on the elevation of your barometer, determine the pressure offset to be added/subtracted to the NWS reading. (This involves applying a simple equation.) Apply the offset to the NWS reading and adjust your barometer to match this final number. I recommend the first approach.
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