8.1 Physics Of The Athomsphere Flashcards
What are mixed gasses known as?
Air
What does the stratosphere comprise of?
21% oxygen
78% nitrogen
1% other gasses
The composition of air remains relatively consistent as altitude increases but what happens to pressure?
It decreases
The pressure level of each part of the mixture is proportional to what?
To mass contribution
Is the air compressible?
Yes
What does the air compressibility allow for?
Allows density to vary with pressure and temperature
What is the atmosphere?
A giant mass of air that turns together with the earth
The atmosphere has what shape?
Concentric shape
What is the average height of the atmosphere?
760KM
What are the 5 main regions of the atmosphere?
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Where does the troposphere start and where does it extend?
Starts at earths surface and extends 8 to 14.5 kilometres high (5-9 miles)
Where do most light and turboprop aircraft fly?
In the troposphere
Where there is the most water Vapor
Most cloud formation
What movement happens in the troposphere and why?
Vertical movement
Warm air rise
Cold air decrease
Direct consequence of solar heating
What is the tropopause?
Thermodynamic gradient layer
Marks end of troposphere
Approx 17 kilometres (9 miles) above equatorial regions
What is the average altitude of the tropopause?
11KM (36000ft)
Where is the regular cursing altitude of modern jet aircraft?
The tropopause
Why is the troposphere more favourable for cursing altitude?
The air is thinner
Has less drag
Higher fuel efficancey
Above most weather turbulences
The tropopause is a boundary layer between what and can also be called what?
Between troposphere and stratosphere
Be described as isothermal layer - the temp is constant through
what is the temperature constant at in the stratosphere?
-56.5 degrease Celsius
why is the stratosphere favorable for cursing?
because it can avoid all weather
what do many aircraft do in the stratosphere?
they cruse here
in the stratosphere the temperature does not vary with what?
temperature does not vary significantly with altitude
where does the stratosphere start and where does it extend to?
starts above the troposphere are extends 50KM (30 miles)
what does the stratosphere contain?
a protective ozone layer
the stratosphere is to dry for what?
to dry for clouds
what could penetrate the stratosphere?
vigorous thunderstorms can penetrate
what are the properties of the atmosphere?
aircraft flight is highly influences by quantity of air mass it operates in
kea factors are pressure, temperature, density, humidity
what are particles pulled to the center of the earth by?
gravity
what is the unit of pressure?
pascals (Pa)
what is the equation for atmospheric pressure?
P = F / A
p - pressure
F - force
A - exerted on surface area
when does air have grater pressure compared to what distance from it?
has grater pressure at sea level than it does at 10KM
what is pressure at sea level said to be?
1013.25hPa
what is 1 atmosphere in pascals, hectopascals, millimeters of mercury, inches of mercury, pound per square inch?
101325Pa
1013.25hPa
760mmHg
29.92mHg
14.7psi
what is atmospheric temperature?
temperature is a measure of average kinetic energy of monocles
what does actual atmospheric temperature equal to?
outside air
when does the temperature of air change?
changes with height due to convection
when is atmospheric temperature stable and what is the temperature?
stable at 36,000ft at -56.5 degree Celsius
what is atmospheric density?
mass per unit volume
what does density generally describe?
amount of mass pulled in to a space
what is the equation for density?
p = m / v
p - density
m - mass
v - volume
density and pressure are proportional but what changes with height?
they are inversely proportional to height
when would density decrease?
as temperature increases
what is less dense walm air or cool air?
walm air
what does air density vary with?
relative humidity
what is relative humidity a measure of?
the amount of water present in the air compared to the amount of water vapor
what happens as humidity increases?
air density decreases
what happens to relative humidity at 40,000ft?
relative humidity decreases but with a 1%-2% increase in altitude
humidity is greatly affected by what?
temperature
what does air density affect?
pressure and temperature
what s the international standard atmosphere for pressure, density, temperature?
pressure - 1013.25hPa
density - 1.225KG/m^3
temperature 288.15K / 15 degree Celsius
for ISA air temperature decreases when?
with altitude at linier rates
for ISA what do temperature pressure and density vary with?
the atmosphere
variations in atmosphere quantities must be what?
must be averaged to a standard
in ISA for every 1,000ft what happens?
temp drops by 6.5 degree Celsius
when there is an increase in altitude up to the tropopause what happens?
the temperature, density, pressure and density will decrease
pressure decreases with what?
decreases with altitude not linier matter
what is speed?
the distance a moving object covers in a unit of time
what is the equation for acceleration?
acceleration = change in speed / time
what is the equation for force?
f = m * a
what is acceleration due to?
due to earths gravity
(9.8m/s^2)
when is work done?
when an object is moved over a distance
what is the equation for work?
work = n * m
what is power a measure of?
watts
what is the equation for power?
work over time
d / t
sound waves are the same as what?
same as pressure waves
what is the equation for speed of sound?
a = 20 *square root t (m/s)
speed of sound depends on what?
temperature
when is the speed of sound lower and why?
is lower at higher altitudes because temperature is lower
