Atmosphere

Question 1

Name permanent constiuent gases in the atmosphere (and list there percentages)

Answer 1

Nitrogen (78%)
Oxygen (21%)
Trace gases (1% - Argon, CO2, Neon, Helium, Methane, Krypton, Hydrogen, Xenon, Ozone)

Question 2

What type of varialbe constiuents can be found in the atmosphere

Answer 2

Solids (Particulates - dust, sand, salt, volcanic ash)
Liquids: Water droplets
Gases: Water vapour etc.

Question 3

How does CO2 contribute to temprature control in the atmosphere?

Answer 3

It absorbs certain heat radiation in long wave radiation bands

Question 4

What happens to Oxygen in the higher reaches of the atmosphere

Answer 4

Oxygen dissasociates from its molecular form (o2) to its atomic form (o) when under the influence of short wave solar radiation

re-combination takes place with some atoms to form Ozone (o3) which absorbs more short-wave rads.

these process create warmer layers in the higher parts of the atmosphere.

Question 5

What is interesting about gases in the upper reaches of the atmosphere

Answer 5

They are moving with great speed (indicating a relative high temprature) but they are so spaced out that we see lower temprature drop.

Question 6

What does water vapour do with solar radiation?

Answer 6

water vapour absorbs well in specific long wave radiation bands which thus promotes heat retention in the lower atmosphere.

through its absorption of heat, and changes in state thanks to latent heat (i.e. evaporating —> moving —> condensing/precipitating)

it is this process, and the varying states of water content in a specific area of the atmosphere that account for clouds/precipitaiton/fog

Question 7

Name some solids that may be present in the atmosphere

Answer 7

Sea Salt (from cyclones/torndaoes), Dust, Sulphur, Ash

Question 8

Name the layers of the atmosphere in ascending order

Answer 8

Troposphere, Stratosphere, Mesosphere, Thermosphere (Ionsphere/exosphere)

Question 9

how high, in miles and feet, does the Earth’s atmosphere extend upwards?

Answer 9

350 Miles = 1848000 ft

Question 10

How would you express positive or minus pressure using two letters?

Answer 10

PS or MS

Question 11

What is the world wide height of the tropopause?

Answer 11

36090 ft (6.8 Miles)

Question 12

where does most of the weather occur within the atmosphere?

Answer 12

within the Troposphere

Question 13

where does the Stratosphere end?

Answer 13

160,000 ft (30.3 mi)

Question 14

How is temperature typically controlled within the thermosphere?

Answer 14

conduction and convection - radiation absorption does also play a role

Question 15

How is temperature typically controlled within the Stratosphere?

Answer 15

mainly through absorbtion of radiation

Question 16

at what point does the Mesosphere end?

Answer 16

280,000 ft (53.3mi)

Question 17

at what point does the thermosphere end?

Answer 17

2,000,000 ft (378 mi)

Question 18

what is above the thermosphere?

Answer 18

exosphere

Question 19

name the atmospheric boundaries, along with associated altitudes in ft

Answer 19

Tropopause (36090ft) Stratopause (160,000 ft)
Mesopause (280,000ft) Thermopause (2,000,000)

Question 20

What can cause the thermopause to vary? and why?

Answer 20

Heat - temprature can cause air to rise, thus increasing the height of the tropopuase at the equators and causing it to decrease at the poles

Question 21

What height range can the tropopause typically occupy and where?

Answer 21

25000ft (at the poles) - 55000ft (at the equator)

Question 22

what three measures of atmosphereic pressure would we typically see?

Answer 22

hPa (hectorpascals), milibar, and inHg (inches of mercury)

Question 23

What device is used to measure pressure

Answer 23

Barometer

Question 24

how would you describe air pressure in terms of weight?

Answer 24

Pressure is the force of the air molecules pushing against you at a specific altitude

Question 25

what is the formula for pressure?

Answer 25

P(ressure) = F(orce) --------- A(rea)

Question 26

what is the formula for density

Answer 26

Rho(density) = m(ass) ----------- V(olume)

Question 27

what is the SI unit for density?

Answer 27

Kg/m3

Question 28

What is the diffence, in lay-terms, between pressure and density

Answer 28

density is how much stuff is in a unit area, and pressure is how quickly the stuff (molecules) move around that area - they are thus linked

Question 29

what does the abbreviation MSL mean?

Answer 29

Mean Sea Level

Question 30

What is the significance of the tropopause in terms of weather?

Answer 30

Clouds rarely form above the tropopause, and this is typically where wind speeds are highest Jet streams occur here and this is typically where you get the most significant CAT

Question 31

what does CAT stand for?

Answer 31

Clear Air Turbulence

Question 32

What is the definition of a jet stream?

Answer 32

wind speeds consistently above 80kts

Question 33

where is a jet engine typically most efficient? and why?

Answer 33

at the Tropopause - the ambient temperature typically levels off at this point, with the reduction in density not being counterbalanced by any further drop in temperature.

Question 34

What will happen to the temperature of the tropopause at the poles and at the equator?

Answer 34

at the poles the temprature of the tropopause will be higher whereas at the equator it will be lower due to variance in height.

Question 35

What is the range of tempratures typically for the tropopause

Answer 35

as warm as -40c in the winter and as cold as -80c in the tropical summer

Question 36

what is an approx value of changes in pressure with height?

Answer 36

1 hPa per 30ft - below 20000ft, then it is 1hPa per 50ft

Question 37

how do temprature changes effect pressure?

Answer 37

cold = more pressure, warm = less pressure

Question 38

why does density decrease despite air getting cooler as we move through the troposphere and stratosphere?

Answer 38

pressure effect is greater, thus causing density to decrease with height

Question 39

What is the calculation for air density?

Answer 39

rho (p) = p/RT rho = density (ratio of mass to volume kg/m3) p = pressure R = gas constant T = absolute temperature

Question 40

what is 1 millibar equal to?

Answer 40

1 hectopascal

Question 41

what is the ICAO SPS for pressure?

Answer 41

1013.2 hPa

Question 42

what is one bar typically? (1000mb)

Answer 42

the approximate atmospheric pressure at sea level

Question 43

what is the SPS in in (in Hg)

Answer 43

29.92 in Hg

Question 44

Name two different types of barometer

Answer 44

Mercury Barometer and Aneroid Barometer

Question 45

which is more accurate, a mercury barometer or an aneroid barometer?

Answer 45

Mercury barometer

Question 46

which type of barometer is used in aircraft?

Answer 46

Aneroid barometer

Question 47

what does ISA mean?

Answer 47

international standard atmosphere - reference for the average state of the atmosphere

Question 48

Who defines the ISA

Answer 48

ICAO (International Civil Aviation Organisation)

Question 49

What is the ISA value for surface pressure

Answer 49

1013.2 hPa (29.92 in Hg)

Question 50

What is the ISA value for surface temperature at MSL?

Answer 50

15 degrees celsius

Question 51

What is the ISA lapse rate up to the tropopause?

Answer 51

1.98c (2c) for every 1000 ft (6.5c/km)

Question 52

What is the ISA average temp for the tropopause

Answer 52

MS 56.5

Question 53

what is the ISA average density AMSL?

Answer 53

1.225 kg/m^3

Question 54

what typically happens around the 'pauses' with regards to temperature?

Answer 54

you get an isothermal layer - i.e. the temperature remains constant.

Question 55

what is the avg. temp at the stratopause?

Answer 55

0c

Question 56

what typically happens to the temprature in the stratosphere?

Answer 56

we see an inversion - i.e. it increases from the tropopause.

Question 57

what is the avg temp at the mesopause?

Answer 57

-90c

Question 58

what happens to the temprature in the mesosphere?

Answer 58

we see a drop in temps

Question 59

what happens to the temeprature in the thermosphere?

Answer 59

we see an inversion in temps

Question 60

What is density inversly proportional to? How would we express this as a formula?

Answer 60

rho(density = Pressure (p) / R(gas constant)*T(absolute temperature)

Question 61

why can hot air hold more moisture?

Answer 61

because there are more gaps between air molecules