The Pressure screen will equal the Baro screen when the REF ALT on the Baro sub-menu is equal to zero (0). This measurement is displaying the station pressure at all times (there is no REF ALT input). The 4250 is the only Kestrel with a dedicated station pressure screen. Density Altitude is not related to the Altitude screen nor the REF ALT or REF BARO in any way. Shows you the current density altitude for your current location. If the reference altitude is zero, then the Kestrel is displaying station pressure. Shows you the current pressure adjusted for sea level based on the reference altitude.
Pressure altitude formula update#
If the altitude is not reading correctly you most likely need to update the reference barometric pressure to the local, current barometric pressure. Shows you current altitude based off of the pressure sensor and reference barometric pressure. If you turn Sync Alt OFF, the Kestrel will automatically turn Sync Baro to OFF and vice-versa. PLEASE NOTE: If you turn Sync Alt ON, the Kestrel will automatically turn Sync Baro to ON and vice-versa. If set to ON: When you adjust the REF ALT, the Kestrel will automatically update the REF BARO with the updated altitude value.If set to OFF: When you adjust the REF BARO, the Kestrel will not change the REF ALT value.įound in the Barometric Pressure sub-menu (center button on Baro screen).If set to ON: When you adjust the REF BARO, the Kestrel will automatically update the REF ALT with the updated barometric value.Sync Baroįound in the Altitude sub-menu (center button on Alt screen). PLEASE NOTE: This value does not affect the density altitude (all models) or ballistic solution screen (ballistic models only). In this case, you would not have to adjust this reference value when changing altitudes. If you would like to know your station pressure, you would set the reference altitude to zero (0). As long as you do not change altitudes, the barometric pressure will remain correct. This value needs to be set to your current, local altitude in order for the barometric pressure to read correctly. Ref Altįound in the Barometric Pressure sub-menu (center button on Baro screen). PLEASE NOTE: This value does not affect the density altitude (all models) or ballistic solution screen (ballistic models only). If the atmospheric pressure changes, altitude will change even if unit did not change locations. This value needs to be set to your current, local barometric pressure in order for the altitude to read correctly. Stands for reference barometric pressure. Please note: Density Altitude will always read correctly on your Kestrel independent of your location or any reference values.įound in the Altitude sub-menu (center button on Alt screen). In other words, it is the air density expressed as an altitude above sea level. The altitude at which you would find the local air density, assuming standard atmospheric conditions (ISA). When measuring pressure at sea level, station pressure and barometric pressure are equal. The station pressure adjusted to mean sea level. house, the top of a mountain, or on the shore). The pressure measured at a station, without any adjustment. Please note: Kestrels do not contain a GPS chip. GPS AltimeterĪn instrument that determines your local altitude based on a GPS chip in the unit and satellites triangulating your location. Pressure Altimeter <- KestrelĪn instrument for determining elevation based on changes in air pressure. I saw a value of 101800 or so for an altitude of 800ft, which is completely wrong, and then the output starts turning into negatives around 100,000ft.An instrument for measuring atmospheric pressure, used especially in weather forecasting. Any idea what the issue with this equation is?ĮDIT: inaccuracy alone isn't the problem, it's not giving the right values for anything. Upon completion of the equation, which I think spits out Pascal values, they don't match what a pressure would realistically look like at that altitude (comparing the output value to one from Wolfram). molar mass of dry air M = 0.0289644 kg/mol.universal gas constant R = 8.31447 J/(mol.Earth-surface gravitational acceleration g = 9.80665 m/s2.sea level standard temperature T0 = 288.15 K.sea level standard atmospheric pressure p0 = 101325 Pa.I am trying to find out the pressure at a given altitude but have been disappointed to find the following equation does not work at all: (h = height in meters)