Density Altitude
From the user, an air temperature ,
a station pressure ,
and a dewpoint temperature
The density altitude calculation is quite complex. Before calculating the density
altitude, the virtual temperature must be calculated first. To perform all the
calculations for the density altitude calculation, the air temperature must
be in units of Kelvin ,
the station pressure must be in units of inches of mercury and
millibars
, and the dewpoint temperature must be in units of degrees Celsius
To see how to convert the temperatures and pressure, see the links below:
pressureConversion.php
tempConvert.php
To calculate the virtual temperature ,
a vapor pressure must
be calculated first using the equation below.
Then using station pressure in units of millibars ,
the virtual temperature can be calculated.
The virtual temperature answer will be in units of Kevin
and needs to be converted to Rankine to calculate the density altitude. To see
how to convert Kelvin to Rankine, see the link above. Finally, the density altitude
can be calculated. Using the virtual temperature in units of Rankine
and station pressure in inches of mercury
The density altitude will be units of feet. To convert, the answer to meters,
see the equation below:
