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Suunto Vector's Barometer
While I have read a number of thread about the Suunto Vector, I am still
a little confused about the operation of the barometer. I got a new Vector over the weekend and I really want to be able to understand it's operation. From the rather weak manual that came with it I know that there are 4 barometer screens (or sub-modes, as Suunto calls them). 1. The main screen 2. The pressure difference measurement screen 3. 4-day memory screen 4. Sea level screen What I am confused about is the how the barometer reading on the main screen (1) differs from the reading on the sea level screen (4). For example, right now (4/26/2005 in Salt Lake City, UT)the main barometer screen read 24.85 inHg while the Sea Level screen reads 29.20 inHg. NOAA.org says the reading should be around 29.85 inHg at the SLC airport, about 1800 ft. lower that I am right (so that's pretty close). What is the main barometer screen(1) really telling me? And why doesn't show a reading closer to what the local weather says it should be? Could this watch be defective? Also, I calibrated the altimeter using a known altitude, rather that adjusting the Sea Level pressure. As I understand it, this will give me a more accurate altimeter reading. Correct? Thanks, Jason |
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#2
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I beleive the main screen is giving your local actual reading. The sea
level screen gives your local actual corrected to sea level by a function based on altitude, which is the same number given on the weather reports except theirs is based on actual and altitude at the weather observation point. Local actual varies from point to point depending on a lot of things related to frontal movements, local topography, temperature variations and wind. Setting the altitude to a known local altitude is always the best way to get an accurate reading. From the numbers you've given, it sounds like the Vector is working fine. Tommy T. "holmbrew" wrote in message ... While I have read a number of thread about the Suunto Vector, I am still a little confused about the operation of the barometer. I got a new Vector over the weekend and I really want to be able to understand it's operation. From the rather weak manual that came with it I know that there are 4 barometer screens (or sub-modes, as Suunto calls them). 1. The main screen 2. The pressure difference measurement screen 3. 4-day memory screen 4. Sea level screen What I am confused about is the how the barometer reading on the main screen (1) differs from the reading on the sea level screen (4). For example, right now (4/26/2005 in Salt Lake City, UT)the main barometer screen read 24.85 inHg while the Sea Level screen reads 29.20 inHg. NOAA.org says the reading should be around 29.85 inHg at the SLC airport, about 1800 ft. lower that I am right (so that's pretty close). What is the main barometer screen(1) really telling me? And why doesn't show a reading closer to what the local weather says it should be? Could this watch be defective? Also, I calibrated the altimeter using a known altitude, rather that adjusting the Sea Level pressure. As I understand it, this will give me a more accurate altimeter reading. Correct? Thanks, Jason |
#3
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"holmbrew" wrote in message ... While I have read a number of thread about the Suunto Vector, I am still a little confused about the operation of the barometer. I got a new Vector over the weekend and I really want to be able to understand it's operation. From the rather weak manual that came with it I know that there are 4 barometer screens (or sub-modes, as Suunto calls them). 1. The main screen 2. The pressure difference measurement screen 3. 4-day memory screen 4. Sea level screen What I am confused about is the how the barometer reading on the main screen (1) differs from the reading on the sea level screen (4). For example, right now (4/26/2005 in Salt Lake City, UT)the main barometer screen read 24.85 inHg while the Sea Level screen reads 29.20 inHg. NOAA.org says the reading should be around 29.85 inHg at the SLC airport, about 1800 ft. lower that I am right (so that's pretty close). What is the main barometer screen(1) really telling me? And why doesn't show a reading closer to what the local weather says it should be? Could this watch be defective? Also, I calibrated the altimeter using a known altitude, rather that adjusting the Sea Level pressure. As I understand it, this will give me a more accurate altimeter reading. Correct? Thanks, Jason The main screen indicates the actual current barometric pressure at your location and elevation. The Sea Level screen is the theorectical barometric pressure with the atomospheric conditions at your location if you were actually at sea level. Using your example, if the main screen showed 24.85 and the sea level screen showed 29.20, then if you could suddenly go to the bottom of a hole at your location with a bottom at sea level, then the barometer main and sea level screens would both read 29.20. The value you see on the Sea level screen is referred to by pilots as the "altimeter setting". Aviation traffic controllers and weather people frequently give out this altimeter setting for a specific location. If you are at the airport and ATC says the altimeter setting is 29.20, then if you adjust your Vector so that the sea level screen reads 29.20, then your altimeter is calibrated and should indicate you current elevation correctly. The number you are getting at NOAA.org may be this altimeter setting rather than the actual local barometric pressure at the local elevation. The easiest way to calibrate your altimeter if you know your current elevation is to set it the way you described. Setting the altimeter using the weather service's "altimeter setting" is the way to set it if you don't know you current elevation. This is what pilots have to do when they are up in the air and don't know their altitude but want to calibrate their altimeters. BobT |
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