Nature of the Atmosphere

Question 1

How high do the gases that comprise the atmosphere typically raise up in the atmosphere?

Answer 1

1000 km above Mean Sea Level

Question 2

What % of the mass of the atmosphere lies above 30 km?

Answer 2

1%

Question 3

What is the rough molecular composition of molecules in the air?

Answer 3

Nitrogen = 78%
Oxygen = 21%
Other gases (Argon, Carbon Dioxide, Neon, Helium) = 1%

Question 4

What are the 4 main layers of the atmosphere? How does temperature decrease with height in each of them?

Answer 4

• Troposphere (temp decreases with height)
• Stratosphere (isothermal layer in lower layer, then increases)
• Mesosphere (temperature decreases with altitude)
• Thermosphere (temperature increases with altitude)

Question 5

What are heights of tropopause at the poles and at the equator?

Answer 5

• 20,000 ft at the poles

- 36,000 ft at the equator

Question 6

Which layer of atmosphere does majority of weather events occur?

Answer 6

Troposphere

Question 7

What is ISA ELR?

Answer 7

-2 C/1000 ft

Question 8

What is the ISA temperature at the tropopause?

Answer 8

-56.5 C

Question 9

What are average beginning and end heights of the stratosphere?

Answer 9

Begins at tropopause to around 160,000 ft

Question 10

Are there any significant weather in stratosphere?

Answer 10

No not normally

Question 11

What are height beginning and ends of the mesophere?

Answer 11

160 000 ft –> 280 000 ft

Question 12

What are the height beginning and ends of the thermosphere?

Answer 12

Begins at 280 000 f to 690 km above the earth.

Question 13

What are ISA pressure, temperature, density and ELR values?

Answer 13

• Pressure = 1013.25 hPa
• Temperature = + 15 C
• Density = 1.225 kg/m^3
• ELR = -2/1000 ft

Question 14

What height do humans require supplemental oxygen to function?

Answer 14

10,000 ft

Question 15

What is QNH altitude?

Answer 15

• Height Above MSL (AMSL)

Question 16

What is QNE altitude? When is it used?

Answer 16

• Altitude related to ISA 1013.25 hPa.

- Used for A/C above 18,000 ft

Question 17

What is QFE? When is an application of it?

Answer 17

• Height above aerodrome

Question 18

What effect does decreasing temperature, pressure, density or increasing altitude have on A/C performance?

Answer 18

• Decreasing temperature will improve A/C performance
• Decreasing pressure will decrease A/C performance
• Decreasing density will decrease A/C performance
• Increasing altitude will decrease A/C performance

Question 19

What occurs at higher altitudes re. A/C performance?

Answer 19

• TO and landing distances are increased
• Climb rates are decreased
• Powerplants and propellers are less efficient