The Atmosphere Flashcards
Height of the Troposphere at the poles
30,000 ft
Height of the Troposphere at the equator
60,000 ft
Layer of atmosphere most flying happens in
Troposphere
How much of each gas in the atmosphere
Nitrogen
Oxygen
Other
Nitrogen - 78%
Oxygen - 21%
Other - 1%
What unit?
Force is measured in?
Newtons (N)
What unit?
Mass is measured in?
Kilogram (Kg)
What value and unit?
Gravity constant is measured in?
9.81 m/s^2
M F A
Mass = Force / Acceleration
General Knowledge
REMEMBER:
Enforce MultiFactor Authentication
What is the definition of pressure?
Amount of force spread over an area
Equation for pressure
General Knowledge
Pressure = Force / Area
What is the pressure of the following flight levels?
Sea Level
5000
10,000
20,000
30,000
35,000
Sea Level - 1013
5000 - 840
10,000 - 700
20,000 - 466
30,000 - 300
35,000 - 240
Why does an aircraft have a “ceiling” altitude?
At altitude, air pressure is reduced.
1% difference of pressure on upper surface of wing at 20,000ft is less than 1% difference at sea level
Wings can therefore lift less weight at higher altitudes
What are the values of ISA at sea level?
Temperature
Density
Pressure
- Temperature - 15 C
- Density - 1.225 kg/m^3
- Pressure - 1013.2 hPa
What are the values of ISA lapse rates?
Temperature lapse rate
Pressure reduction (up to ????? ft)
Temperature: -1.98 C per 1000 ft
Pressure: 1 hPa per 30 ft up to 20,000 ft
Which gas law is defined below?
At a constant temperature, the volume of a gas is inversely proportional to its pressure
Boyles Law (PV = K1)
P = pressure (Pa)
V = Volume (m^3)
K1 = Constant (Joules)
If a contained with fixed amount of molecules inside is reduced in volume, more molecules hit the sides, causing greater pressure
Which gas law is defined below?
The volume of gas at a constant pressure is directly propotional to its absolute temperature
Charles Law (V = K2T)
T = Absolute temperature (Kelvin)
K2 = Constant produced
Which gas law is defined below?
The pressure of an atmosphere is simply the sum of pressures of the individual gases within the atmosphere
Daltons Law (Ptotal = P1 + P2 + P3 + Pn)
Ptotal = sum of all pressures
Pn = Individual pressure
Which gas law is defined below?
The amount of gas dissolved in a liquid is proportional to the gas pressure outside of the liquid.
If the pressure of a liquid is reduced, then the amount of gas dissolved in the liquid will reduce
Henerys Law (P = Kh C)
P = partial pressure
C = concentration of the solute
Kh = Constant with dimensions of pressure divided by concentration
Remember the gas laws
Boil (Boyle) at constant temperature
King Charles under pressure (constant pressure)
Dalton needs to Pee
Henry drinks coke (pressure liquid)
General Knowledge
What happens to air density with an increse in altitude?
Becomes less dense
What happens to air density with an increase in temperature?
Air becomes less dense
Cold = Dense = Thicker
Warm = Less Dense = Thinner
Moist (humid) air contains MORE or LESS water vapour than dry air?
MORE
Water vapour is MORE or LESS dense than air?
LESS
Humid air weights MORE or LESS than dry air?
LESS
The amount of water vapour that air can contain is dependent on what?
Temperature
Air of HIGHER temperature can contain MORE or LESS water vapour?
MORE
Air of LOWER temperature can contain MORE or LESS water vapour?
LESS
Engine Power
LESS dense air means MORE or LESS oxygen?
What does this do to power available?
LESS oxygen
LESS power
Engine Power
MORE dense air means MORE or LESS oxygen?
What does this do to power available?
MORE oxygen
MORE power
Aerodynamic Lift
LESS dense air means MORE or LESS lift?
LESS lift
What is Boyles Law
At a constant temperature, the volume of a gas is inversely proportional to its pressure
Pressure increases, volume decreases
What is Charles Law
It a constant pressure, the volume of gas is directly proportional to its absolute temperature.
If temperature increases, volume increases
What is Henrys Law
The amount of gas dissolved in a liquid is proportional to the gas pressure outside of the liquid.
If the pressure of a liquid is reduced, then the amount of gas dissolved in the liquid will reduce
Think about the squeezed bottle and water. Release the bottle cap, the water turns into cloud
What is Daltons Law
The pressure of an atmosphere is simply the sum of pressures of the individual gases within the atmosphere
Ptotal = P1 + P2 + P3
What is Newtons 1st Law
An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force
Object at rest or in motion = CONSTANT
What is Newtons 2nd Law
The acceleration of an object depends on the mass of the object and the amount of force applied
Mass = Force / Acceleration
Heavier the object, more force required to move it at the same acceleration as a lighter object
What is Newtons 3rd Law
Whenever one object exerts a force on another object, the second object exerts an equal and opposite on the first
Opposite and Equal Reaction
At the same IAS, as altitude inceases, what happens to dynamic and static pressure
- Dynamic pressure REMAINS CONSTANT
- Static Pressure DECREASES
As altitude increases, the atmospheric (static) pressure reduces.
Since the air is “thinner” at altitude, the aircraft travels faster (physically), but from a DYNAMIC pressure point of view, the dynamic pressure remains the SAME (the same molecules of air collected in the same time, but over a greater distance)
