Density altitude
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Density altitude is the altitude in the International Standard Atmosphere at which the air density would be equal to the actual air density at the place of observation. "Density Altitude" is the pressure altitude adjusted for non-standard temperature.
Both increase in temperature and increase in humidity cause a reduction in air density. Thus in hot and humid conditions the density altitude at a particular location may be significantly higher than the geometric altitude.
Density altitude can be calculated from atmospheric pressure and temperature (assuming dry air).
<math> \mathrm{DA} = 145426 \left[1-\left(\frac{P_0/P_{SL}}{\mathrm{T}/T_{SL}}\right)^b\right] </math>
where
<math>\mathrm{DA}=</math> density altitude
<math>P_0=</math> atmospheric (static) pressure
<math>P_{SL}=</math> standard sea level atmospheric pressure (1013.25 hPa)
<math>\mathrm{T}=</math> true (static) air temperature
<math>T_{SL}=</math> standard sea level air temperature(288.15 K)
<math>b=</math> 0.235
[edit] References
- (1 December 1989) Air Navigation. Departments of the Air Force and Navy. AFM 51-40 / NAVAIR 00-80V-49.
- Air Density and Density Altitude. Retrieved on 09 January, 2006.
