THE ATMOSPHERE Flashcards
What’s the atmosphere composed of?
78% Nitrogen
21% Oxygen
1% Argon
0,03% CO2
How high is the troposphere
- At the equator
- 45 deg lat
- At the poles
52’000ft at the equator (-80 deg)
36’090ft at 45 deg lag (-56 deg)
26’000ft at the poles (-50 deg)
How does the troposphere change in height with temp changes?
The colder the temp the lower the troposphere
What layer is above the troposphere?
How far up does it extend and what happens to temperature in this layer and also why does it increase slightly ?
Stratosphere that extends from 36’096ft - 170’000ft
Temp remains constant at start, then increases to 0 deg at the top.
Ozone causes surrounding air to warm
Define ISA?
At MSL: \+15 deg with a decrease of 1,98 deg/1'000ft up to 36'096ft 1013.25 hPa 1225 g/m2 (dry air density 760 g/m2 (water vapor)
What is JSA?
Jet standard atmosphere
Used by engine manufacturers
+15 deg @ MSL and decreasing by 2 degrees/1’000ft to infinity
Define “Specific Heat”
Water has high specific heat
Low specific heat loses and gains heat more quickly
The amount of heat needed to raise the temperature by 1 degree
How is the earth surface heated?
Suns short wave radiation heats the surface of the earth but not the atmosphere. Long wave radiation from the earth heats the atmosphere from below.
Boiling point and freezing point in Fahrenheit?
Boiling point = 212 deg F
Freezing point = 32 deg F
Boiling point and freezing point in Kelvin?
Boiling point = 373 K
Freezing point = 273 K
What is used to measure surface temp?
A Stevenson screen at a height at 4ft
When is insolation highest and when is temp highest?
Insolation highest at 12:00 and temp highest at 15:00
What is the Greenhouse effect?
Atmosphere (water vapour and CO2) is transparent to solar short wave radiation but don’t allow long wave terrestial radiation to leave and go back into space. This leads to an increase in temp on the ground
Where are the “3 breaks” in the troposphere?
1 st: 40 deg lat
2nd: 55 deg lat
3rd: 60-70 deg lat
Occurs where large temp diff occurs.
Co-incides with the Hadley- and Farrel cells
These breaks/temp diff causes strong winds called jetstreams
What’s an Isobar?
Places of equal pressure
How does pressure change with height?
Pressure decreases as height increases and at a decreasing rate
How does the pressure change with height depending of weather it’s warm or cold?
Pressure decreases more rapidly in cold air compared to warm air
How much change in height is 1 hPa at MSL?
27 ft
How does wind blow around a Low/High pressure system in the Northern hemisphere?
Anti-clockwise around a Low
Clockwise around a High
What are the properties of a Low pressure system?
Convergence at the surface and divergence at altitude
What happens to density with height?
What’s the contradiction here?
Density decreases with height
Pressure decreases with height which decreases density but temp decreases with height that would increase density.
Pressure have the overriding effect
Increased humidity also decreases density
Why is there relatively higher density at height over the equator compared to over the poles?
Density decreases relatively quickly in cold air compared to in warm air.
How does density altitude change with deviation from ISA?
By 118,8 deg C per degress away from ISA
How is humidity measured?
By a dry/wet bulb hygrometer
A cloth of destilled water is wrapped around a bulb. Water in the cloth evaporates into the air. Latent heat is absorbed from the atomsphere which lowers the temp scale until saturation occurs. Dew point is then given
How can air become saturated?
By adding extra water vapour or by lowering the temperature
Describe the relationship between
Solid - Liquid - Gas
and they change from one an other
Solid - Liquid is melting, latent heat absorbed
Liquid - Gas is evaporation, latent heat absorbed
Gas - Liquid is condensation, latent heat released
Liquid - Solid is freezing, latent heat released
Gas - Solid directly is called sublimation
Can you convert 12 degrees C to F?
Ballpark - Degrees Celsius multiply by 2 and add 32 (Vice/Versa for F to C). EX: 12x2=24+32=56
