Ch 4 - Atmospheric Density

Question 1

Density =

Answer 1

The mass of air in a given volume (g/m^3)

Question 2

Density decreases with Altitude:

Answer 2

MSL. 1.225 kg/m^3
22,000 0.609 kg/m^3 (roughly 50% MSL)
40,000. 0.302kg/m^3 (roughly 25% MSL)

Pressure has the over ruling affect on density
-> Temperature and Humidity also impact density

Density is proportional to pressure

Density is inversely proportional to temperature and humidity

Question 3

Optimal Performance conditions for an Aircraft

Answer 3

High Density 
Low Altitude 
Fairly Dry
High Pressure
Colder air

Question 4

Density Altitude

Answer 4

Difference between the pressure Altitude and the Density Altitude (where the aircraft thinks it is)

= 120 x ISA Deviation (Gives you an answer in feet)

If it is colder than ISA, you minus the answer (above) from the Pressure Altitude which then gives you the density Altitude.

If it is warmer than ISA, you add the answer (above) to the Pressure altitude which gives you the density altitude