Chapter 2 - The Atmosphere Flashcards
The atmosphere is composed of:
78% Nitrogen
21% Oxygen
0.95% Argon
0.05% Carbon Dioxide
ISA gives standardised values for temperature,pressure,density,etc. in a “standard” atmosphere.
MSL pressure 1013.25 Hpa and temperature is 15 celsius.
Temperature reduces with height at 0.65 degree celsius per 100m
(1.98 degree celsius per 1000 feet)
In the staratosphere temperature remains constant at -56.5 degree celsius up to 20 km.
What’s the percentage of pressure decreases with altitude ?
At 8.000 feet the pressure is 3/4 of its sea level value
At 18.000 feet the pressure is 1/2 that at sea level.
Bu 36.000 feet the pressure has reduced to only 1/4 of its sea level value.
What is the percentage of oxygen in the atmosphere ?
The percentage of oxygen in the atmosphere remains constant up to about 70.000 feet,making up 21% by volume of the air we breathe.
What altitude will pilots need supplementary oxygen ?
The partial pressure of oxygen decreases with increased altitude which is why pilots will need supplementary oxygen above 10.000 feet.
