Additional Information:
Example 1: at 5050 feet elevation, 95 deg F air temp, 29.45
inchesHg 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 dewpoint 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/m^{3} (0.002378
slugs/ft^{3}).
