8.1 Flashcards
Gas proportions
Nitrogen 78%
Oxygen 21%
Other gases 1%
These proportions do not change with altitude
Troposphere
Lowest layer.
Contains the weather system.
Temp drops approx 2 degrees per 1000ft.
Tropopause
Upper limit of troposphere where temperature stops decreasing
Height of tropopause at the Equator and at 45 degrees latitude
Equator 16-18km, 53000-57000ft.
45 degrees 10-12km, 33000-39000ft.
Stratosphere
2nd major layer which is said to be a constant temperature.
Name all the layers in the atmosphere in order
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Where does most ozone reside?
Stratosphere (90%)
Temperature
Measure of internal kinetic energy
Temperatures at freezing and boiling
Freezing
0 degrees
32 Fahrenheit
273.15 Kelvin
Boiling
100 degrees
212 Fahrenheit
373.15 Kelvin
Standard sea level temperatures
15 degrees
59 Fahrenheit
288.15 Kelvin
Lapse rate
Temperature decrease with increase in altitude.
2 degrees per 1000ft in troposphere.
Increase in temperature on density
Reduction of density
Reduction of density
Reduces lift.
Drag gets reduced also.
Pressure
Force over Area.
Forces always acts at right angles to the surface.
Pressure increases with temperature.
Pressures at sea level
14.7 psi
29.92 In.Hg
1013.25 hPa
101325 N/m^2
How is pressure measured?
Using a barometer.
Force over Area.
Isobars
Lines of equal pressure
Pressure altitude
Altitude in which a given pressure occurs in the ISO.
If flying from a high pressure area to a low pressure area you would actually be lower.
Density altitude
Altitude at which air density would be equal to indicated air density at place of observation.
Increase in temperature, decrease in atmospheric pressure will increase density altitude.
Is air density given as height about sea level.
Gauge pressure
Pressure measured above atmospheric pressure.
Static Pressure
Pressure of gas when stationary.
In a Venturi the static pressure is decreased.
Pitot pressure
Also knows as total pressure.
Measured with a pitot tube and used to determine aircraft airspeed.
Measured with manometer.
Density
Mass over Volume.
Expressed in grams or kilograms.
Denoted by rho.
Pressure, temperature and altitude in respect to density.
Increase of pressure increase density.
Decrease of temperature increase density.
Increase altitude decreases density.
What level leads to hypoxia.
10000 ft
Service ceiling and absolute ceiling
Altitude which rate of climb falls to a specific figure.
Altitude which rate of climb falls to zero.
Avogadros law
Equal volumes of gases at same temperature and pressure have the same amount of molecules
Charles law
At constant pressure, volume is directly proportional to temperature.
Boyles law
At constant temperature, volume is inversely proportional to pressure.
Gay Lussacs law
At constant volume, pressure is proportional to temperature
Daltons Law
Total pressure is sum of all partial pressures
Adiabatic process
No heat is lost or gained from surroundings
Boundary layer
Viscosity causes a shearing of layers of air over an object moving through air. The layers formed on surface are called boundary layers.
What does speed of sound depend on?
Temperature of air.
The higher the temperature the higher the speed of sound.
Mach Number
Speed of aircraft over the speed of sound.
Critical Mach number
Lowest Mach number which the airflow of any point of aircraft reaches the speed of sound.
Absolute humidity
Density of water vapour in a given volume of air.
Relative humidity
Water vapour in the air divided by the amount of vapour the air can hold at the same temperature.
Dew point
Temperature at which relative humidity reaches 100%.
What measures humidity?
Hygrometer
