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1. PRESSURE ALTITUDE FORMULA MANUAL
2. PRESSURE ALTITUDE FORMULA PLUS
3. PRESSURE ALTITUDE FORMULA TV
4. PRESSURE ALTITUDE FORMULA DOWNLOAD
5. PRESSURE ALTITUDE FORMULA FREE

You can use this chart to do the temperature correction. No, it's not going to be precisely accurate, as it's based upon two assumptions, one that the barometric pressure at sea level is always 29.92, and a second that atmospheric pressure declines at the rate of 1 inch of mercury per thousand feet of altitude gain - but it's better than nothing. Pressure Altitude = 29.92 - (Physical Altitude / 1000) Station Pressure = 30.14 - (4500 / 1000) = 30.14 - 4.5 = 25.64īut what if we have nothing to tell us the atmospheric pressure at all? Then do this:

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The sea-level barometric pressure is also what is reported by radio and TV stations.Įxample: Your local TV station is reporting that the barometric pressure is 30.14 inches. You may obtain the sea-level barometric pressure from the weather service. Station Pressure = Sea-level Barometric Pressure - (Physical Altitude / 1000) If we have no instrument to measure the local station pressure, but we know the sea-level barometric pressure, we can do this:Īn approximation for the station pressure is: If you have obtained the Pressure Altitude from the table above, you may skip to Step 2 below.

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If you would like to download a copy of the Excel spreadsheet upon which the table above is based, so you can print your own copy, right-click on the following link: Pressure Altitude Spreadsheet. Finding 19.5 in the table, I see the Pressure Altitude is 11,374 feet.

If you aren't familiar with the distinction between station pressure and barometric pressure, you may wish to read this reference: Barometric Pressure and Ballistic SoftwareĮxample: The sensor in my Casio Pathfinder watch reads a pressure of 19.5 inches. Just pick the nearest increment to your station pressure. It's in increments of 0.25 inches of mercury. If you have the station pressure from an instrument you carry, the easiest way to find the Pressure Altitude is to consult the table below. The easiest method for doing this is to print copies of the table and the chart below, and use those.

Then we must compensate the pressure altitude for the temperature, which is usually different than the ICAO standard temperature at the pressure altitude. The pressure altitude is the altitude an aircraft altimeter would read at our location if the reference pressure on the altimeter were set to the current sea-level barometric pressure. However, it will get you pretty close if you don't have a Kestrel or other weather meter to do the calculation for you.įirst we must calculate the pressure altitude, because barometric pressure varies, which affects the pressure altitude. Your Kestrel includes humidity in its calculation of density altitude. This article is an addition to and continuation of the method of using density altitude in computing ballistic performance, Making Ballistic Cards Using Density Altitude

PRESSURE ALTITUDE FORMULA MANUAL

Therefore, the scale on the pressure gauge is relative pressure.Manual Calculation of Density Altitude Manual Calculation of Density Altitude The pressure gauge reading reflects the pressure difference between the fluid pressure and the surrounding air. The zero pressure indicated on a general pressure gauge is atmospheric pressure. In most practical engineering problems, because the atmospheric pressure experienced by the fluids is balanced with each other, the real pressure is relative pressure, so relative pressure is generally used to express static pressure.

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Knowing from Formula (1), the absolute pressure is equal to the relative pressure plus atmospheric pressure, that is

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When the atmospheric pressure Pa is on the free surface of the liquid, That is, the absolute pressure minus the local atmospheric pressure, the relative pressure value is obtained, and is expressed by the letter Pq, (Formula 1) The pressure port U calculated from the zero point makes relative pressure. The pressure displayed by the pressure gauge is the gauge pressure (relative pressure), which refers to the difference between the real pressure and atmospheric pressure somewhere inside the device. Since the pressure measured by most pressure gauges is relative pressure, the relative pressure is also called gauge pressure. The other type of pressure is based on absolute vacuum, which is called absolute pressure. Relative pressure is a pressure expressed with atmospheric pressure as a reference, and is one of the methods for expressing pressure. All you Need to Know about Relative Pressure Formula