Chapter 1 - The Atmosphere Flashcards
What is the composition of the gases in the atmosphere up to 60km?
78% Nitrogen
21% Oxygen
1% Other gases (0.95% Argon)
What is the ranging amount of water vapour in the atmosphere and what is it affected by?
0-4% depending on:
- Altitude
- Location
- Temperature
What is the average amount of water vapour in the atmosphere?
1%
How high is the ozone layer?
Approximately 25km
How high is the tropopause at the equator, the poles and mean level?
16-18km at the equator
8-10km at the poles
11km on average
What is the temperature lapse rate in the troposphere in ft and m?
- 2degC per 1000ft
- 6.5degC per 1000m
How much of the atmospheric air mass is in the troposphere and why?
About 75% due to compression via gravity
Where is almost all of the water vapour in the atmosphere and why?
The troposphere, due to gravity.
Where does most visible weather phenomena take place?
Troposphere
What can affect the thickness of the troposphere?
Temperature
Pressure
Location
What are the characteristics of the tropopause?
It is the point at which temperature no longer decreases with altitude.
Above it the atmosphere is absolutely stable so no air can rise through it and instead can only move horizontally.
It acts as a partial weather barrier.
What is the temperature of the tropopause on average and at the equator and the poles?
Average: -56.5degC
Equator: -75degC
Poles: -40 - -50degC
What is meant by: The first section of the stratosphere (just above the tropopause) is isothermal?
The temperature stays the same/the lapse rate is 0.
What are the standard ISA conditions and what is is used for in aviation?
MSL temperature = +15degC
MSL density = 1.225kg/m3
MSL pressure = 1013.25mbar or hPa
It is used to standardise all aircraft instruments.
What are the approximate pressure levels at 0, 10000, 20000, 30000, 40000 and 50000 ft?
Respectively: 1013hPa 700hPa 500hPa 300hPa 200hPa 100hPa
