To
use the calculator, just click the type of units that
you will be entering, then enter the altitude, temperature,
altimeter setting and dew point. Then click the calculate
button.
Additional
Information:
Example 1: at 5050
feet elevation, 95 deg F air temp, 29.45 inches-Hg
barometric pressure and a dew point of 67 deg F, the Density
Altitude is calculated as 9252 feet.
Example
2: at 1540 meters elevation, 35 deg C air temp,
997 hPa barometric pressure and a dew point of 19 deg C,
the Density Altitude is calculated as 2821 meters.
Air
density is affected by the air pressure, temperature and
humidity. The density of the air is reduced by decreased
air pressure, increased temperatures and increased moisture.
A reduction in air density reduces the engine horsepower,
reduces aerodynamic lift and reduces drag.
Input
Values:
The
elevation (or altitude) is the geometric elevation above
mean sea level, and is the elevation at which the altimeter
setting, temperature and dew point have been measured.
The
altimeter setting is the value in the altimeter's Kollsman
window when the altimeter is set to correctly read a known
elevation. The altimeter setting is generally included in
NWS reports. The altimeter setting is not the same as the
sea level corrected barometric pressure.
This
calculator uses dew-point rather than relative humidity
because the dew point is fairly constant for a given air
mass, while the relative humidity varies greatly as the
temperature changes.
Output
Values:
The
density altitude is the altitude in the International Standard
Atmosphere that has the same density as the air being evaluated.
The
absolute air pressure is the actual air pressure, not corrected
for altitude, and is also called the station pressure.
Relative
density is the ratio of the actual air density to the standard
sea level density, expressed as a percentage.
The
ICAO International Standard Atmosphere standard conditions
for zero density altitude are 0 meters (0 feet) altitude,
15 deg C (59 deg F) air temp, 1013.25 mb (29.921 in Hg)
pressure and 0 % relative humidity ( absolute zero dew point).
The standard sea level air density is 1.225 kg/m3
(0.002378 slugs/ft3).
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