M8.1 Flashcards
(26 cards)
What percentage of the atmosphere does oxygen make up?
21%
What percentage of the atmosphere does nitrogen make up?
78%
What percentage of the atmosphere do trace gases make up?
1%
What is the average height of the atmosphere?
760km
What can cause the height of the atmosphere to change?
Location and season
How high can the exosphere extend to?
1000km
What are the 5 main regions of the atmosphere?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
- Exosphere
What height range is the troposphere in?
The surface to between 8-14.5km high (5-9 miles)
What layer has the most weather activity?
The Troposphere
What layer is the densest?
The Troposphere
Why does considerable vertical movement occur in the troposphere?
Due to solar heating
What is the tropopause?
The layer that marks the end of the troposphere
What is the average height of the tropopause?
11km (36,000ft)
What is the significant of the average height of the tropopause?
Normal cruising height for a modern jet aircraft.
Why do modern jet aircraft cruise near the tropopause?
The air is thinner, resulting in less drag and consequently a higher fuel efficiency. It is also above most of the weather, meaning there will be less turbulence.
What is meant when the tropopause is described as an isothermal layer?
The temperature is constant throughout. (-56.5C)
What height does the stratosphere extend to?
Above the tropopause- 50km (31 miles) high
How does temperature vary with altitude in the stratosphere?
It doesn’t
What 4 factors is aircraft flight influenced by?
- Pressure
- Temperature
- Density
- Humidity
What is the atmospheric pressure at sea level that has been determined by ICAO?
1013.25hPa(14.7 psi) at 15C.
At what rate does atmospheric temperature decrease per 1000ft in altitude?
Roughly 2C per 1000ft until the tropopause, where it is constant at -56.5C.
How does density, pressure and height relate?
Density and pressure are proportional to each other but inversely proportional to height.
What is relative humidity?
Relative humidity is a measure of the amount of water vapour present in the air compared to the maximum amount of water it could hold at a given temperature.
What is the relationship between humidity and air density?
As humidity increases, the air density decreases.
