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An altimeter does not actually measure altitude directly, but rather just atmospheric pressure. So an altimeter is actually a barometer created for a specific purpose. The altimeter uses the changes in atmospheric pressure to determine the changes in altitude. Why does pressure change with altitude? Simply put, the pressure at any given point in the atmosphere around the earth is a result of the weight of the atmosphere above it (pulled down by gravity). For this reason, the higher in the atmosphere you are, the less atmosphere you have above, and the less pressure exerted on you.
Measuring altitude with barometric pressure is not free from difficulties, however. Atmospheric pressure can also change with changes in weather patterns. On an uneventful weather day it is not too unusual for an air pressure change of 1 mbar, caused by temperature changes alone. This 1 mbar change in pressure could result in a skewed altitude reading of up to 26 feet (8 meters). But on an afternoon full of weather changes, like an approaching cold front, air pressure could change by as much as 5 mbar, or more. This could result in a skewed altitude reading of up to 130 feet (40 meters), or more.
Typically, when bad weather is approaching, the pressure will be falling. And the altimeter thinks this decrease in pressure is due to an increase in altitude, so it will read higher than you really are. And the opposite is the case when the weather conditions are improving - the altimeter will read lower than you really are.
In order to compensate for weather changes, an altimeter must be calibrated using a known altitude or a known pressure value. A known altitude can typically be taken from a specific landmark on a topographic map. But if you do not have a known altitude to use, you will need to use a known pressure value. This is typically done with a barometric pressure value. "Barometric Pressure" is the current air pressure at sea level, for a specific location. Barometric pressure is measured several times per day, and can usually be obtained from flight service stations or aviation weather reports.
With all of the changes that affect an altimeter, your elevation can easily be skewed by a few hundred feet in as little as one day's time. You will want to calibrate your unit at least once per day, but for improved accuracy (especially in changing weather conditions), you may want to calibrate it every couple of hours at a known elevation.
What else can I help you with?
What Automatic transmission fluid do you use in a 1992 Mitsubishi pajero?
You can use any SAE certified automatic transmission fluid in your 1992 Mitsubishi. You should never overfill your automatic transmission fluid.
Use altimeter in a sentence?
My wristwatch has an altimeter, which as a backpacker, I find very useful.
How do you use altimeter in a sentence?
my American friend Keith Giles has one which includes an altimeter
How do you turn off altimeter gauge?
Altimeters don't normally need turning off. They are passive devices that work without power. They use an aneriod system, which is mechanical.
How do you use the word altimeter in a sentence?
Most altimeters use changes in atmospheric pressure to determine altitude. The altimeter is a crucial tool in air traffic control.
What instrument is used to measure sun's altitude?
what are all the instruments use to measure altitude
Use a sentence with the word altimeter in it?
ive been looking for this answer for ages
How do you remove the spare wheel bracket of the Mitsubishi pajero rear door?
To remove the spare wheel bracket from the rear door of a Mitsubishi Pajero, first, ensure the vehicle is securely parked and the spare wheel is removed. Use a socket wrench to unscrew the bolts securing the bracket to the door, typically found at the base of the bracket. Once the bolts are removed, carefully detach the bracket from the door. Finally, check for any remaining brackets or hardware that may need to be removed for a clean finish.
How does the pilot use the altimeter when flying the Cessna bush plane?
to measure their altitude
HOW TO Prepare an altimeter?
To prepare an altimeter for use, ensure it is calibrated to the correct setting for the current location, typically using the local air pressure. Check that the altimeter is properly attached and functioning correctly. Familiarize yourself with the altimeter's display and features before relying on it for accurate altitude readings.
What instrument do airplane pilots use to detremine altitude?
S(he) uses an altimeter which a kind of airborne barometer.
Is a Altimeter used specifically for measuring height above sea level yes or no?
It is unwise to demand a yes/no answer to a question unless you are an expert in the field (or, of course, an attorney trying to trap a witness). Some questions just don't have a yes/no answer, and this is one of them. The answer depends on the type of altimeter. For the standard aircraft altimeter which works by measuring pressure it also depends on how you use it.
