Lesson 1 - The Atmosphere Flashcards
The atmosphere is a mixture of gases, but it also includes other non-gaseous substances. Such as?
Droplets of water, particles of smoke, dust and ash.
Up to a height of 60km the atmosphere remains very?
Constant
The approximate composition of ‘dry air’ by volume is…
Nitrogen 78%
Oxygen 21%
Other Gases 1%
The other 1% of gases of ‘dry air’ could be…
Argon
Carbon Dioxide
Hydrogen
Carbon Monoxide
Helium
Carbon Dioxide although present in relatively low proportions has a significant effect on the global climate because…
It strongly absorbs long wave terrestrial radiation thereby acting as a heat source in the atmosphere.
Ozone plays a significant role by…
Absorbing short wave solar radiation, which acts as a heat source on the atmosphere.
Water Vapour comprises of which atoms?
Two atoms of Hydrogen
One atom of Oxygen
‘H2O’
When water vapour condenses into a liquid it creates weather phenomena such as..
Clouds and Rain
In lower atmosphere water vapour can comprise up to…
4% of the total volume.
Pressure and density decrease with…
Increasing altitude through all layers.
Starting from the surface and going upwards, the atmosphere is divided into four main layers….
Troposphere
Stratosphere
Mesosphere
Thermosphere
The boundary layer between each atmosphere layer is known as a?
Pause
In the Troposphere the temperature decreases at about..
2’C per 1000ft (1.98’c to be exact)
Known as the lapse rate.
About 75% of the mass of air and almost all water vapour is contained in the…
Troposphere
Most of the visible weather phenomena take place in the…
Troposphere
The Troposphere on average is how thick?
36,090ft (or 11km) above mean sea level (AMSL)
The upper limit of the Troposhere is defined by
An abrupt change in the lapse rate.
The boundary layer between the troposphere and the stratosphere is called
The Tropopause
Temperature is fixed above the Tropopause at what ISA temperature?
-56.5’C (ISA)
Over the poles the Tropopause is relatively low, but over the equator it is higher. Why?
Because the height of the Tropopause is determined by the temperature of the air in the Troposphere near the surface. ie The warmer the air the higher the Tropopause, the colder the air the Lower. Think of it like expansion.
Tropopause Folds (or breaks) cause abrupt changes in the height of the Tropopause. They occur because of…
the large temperature difference between air masses, the place where fast moving upper air currents (jet streams) are found.
Temperature decreases with height upto the…
Tropopause
The coldest temperature occurs at the highest….
Tropopause
At Sea Level ISA temperature is….
15’C
ISA stands for…
International Standard Atmosphere
In the Stratosphere temperature is constant to approx…
65,000ft
The Stratosphere is generally a good place to fly due to…
- Cloud formation is rare (lack of water vapour and vertical air movement)
- Above hazards of the Troposphere (weather phenomena)
Note: Turbulence is still possible
The Ozone layer is generally found at what height?
82,000ft or 25km
Temperature is constant in the Stratosphere to what height?
Approximately 65,600ft (or 20km)
The temperature rises steadily in the Stratosphere to above 0’C. This is due to?
The Ozone layer absorbing the suns harmful Ultraviolet Light (UV)
Without gravity the atmosphere would…
Float off into space.
It becomes an atmospheric pressure by gravity acting on the air mass pulling it down to earth.
In ISA at Mean Sea Level (MSL), temperature is
+15’C
In ISA at Mean Sea Level (MSL), temperature lapse rate is
1.98’C per 1000ft (2’C for calculations)
Or 0.65’C per 100m
In ISA at Mean Sea Level (MSL), pressure is
1013.25 hPa
or 28.92 InHg
In ISA at Mean Sea Level (MSL), density is
1.225 Kg/m^3
Near the surface assume 1hPa for every “?” of height.
30ft
At 18,000ft (half way to the top of the Troposphere) assume 1hPa for every ”?” of height.
48ft
At 22,000ft, ISA Density is approximately ”?” compares to AMSL
50%
At 40,000ft, ISA Density is approximately ”?” compares to AMSL
25%
The lapse rate within and between layers is not….
Constant and Uniform
