Atmosphere Flashcards

1
Q

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

A

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

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2
Q

What type of varialbe constiuents can be found in the atmosphere

A

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

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3
Q

How does CO2 contribute to temprature control in the atmosphere?

A

It absorbs certain heat radiation in long wave radiation bands

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4
Q

What happens to Oxygen in the higher reaches of the atmosphere

A

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.

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5
Q

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

A

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

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6
Q

What does water vapour do with solar radiation?

A

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

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7
Q

Name some solids that may be present in the atmosphere

A

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

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8
Q

Name the layers of the atmosphere in ascending order

A

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

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9
Q

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

A

350 Miles = 1848000 ft

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10
Q

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

A

PS or MS

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11
Q

What is the world wide height of the tropopause?

A

36090 ft (6.8 Miles)

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12
Q

where does most of the weather occur within the atmosphere?

A

within the Troposphere

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13
Q

where does the Stratosphere end?

A

160,000 ft (30.3 mi)

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14
Q

How is temperature typically controlled within the thermosphere?

A

conduction and convection - radiation absorption does also play a role

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15
Q

How is temperature typically controlled within the Stratosphere?

A

mainly through absorbtion of radiation

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16
Q

at what point does the Mesosphere end?

A

280,000 ft (53.3mi)

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17
Q

at what point does the thermosphere end?

A

2,000,000 ft (378 mi)

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18
Q

what is above the thermosphere?

A

exosphere

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19
Q

name the atmospheric boundaries, along with associated altitudes in ft

A

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

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20
Q

What can cause the thermopause to vary? and why?

A

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

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21
Q

What height range can the tropopause typically occupy and where?

A

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

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22
Q

what three measures of atmosphereic pressure would we typically see?

A

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

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23
Q

What device is used to measure pressure

A

Barometer

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24
Q

how would you describe air pressure in terms of weight?

A

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

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25
Q

what is the formula for pressure?

A

P(ressure) = F(orce)
———
A(rea)

26
Q

what is the formula for density

A

Rho(density) = m(ass)
———–
V(olume)

27
Q

what is the SI unit for density?

A

Kg/m3

28
Q

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

A

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

29
Q

what does the abbreviation MSL mean?

A

Mean Sea Level

30
Q

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

A

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

31
Q

what does CAT stand for?

A

Clear Air Turbulence

32
Q

What is the definition of a jet stream?

A

wind speeds consistently above 80kts

33
Q

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

A

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.

34
Q

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

A

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

35
Q

What is the range of tempratures typically for the tropopause

A

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

36
Q

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

A

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

37
Q

how do temprature changes effect pressure?

A

cold = more pressure, warm = less pressure

38
Q

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

A

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

39
Q

What is the calculation for air density?

A

rho (p) = p/RT

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

40
Q

what is 1 millibar equal to?

A

1 hectopascal

41
Q

what is the ICAO SPS for pressure?

A

1013.2 hPa

42
Q

what is one bar typically? (1000mb)

A

the approximate atmospheric pressure at sea level

43
Q

what is the SPS in in (in Hg)

A

29.92 in Hg

44
Q

Name two different types of barometer

A

Mercury Barometer and Aneroid Barometer

45
Q

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

A

Mercury barometer

46
Q

which type of barometer is used in aircraft?

A

Aneroid barometer

47
Q

what does ISA mean?

A

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

48
Q

Who defines the ISA

A

ICAO (International Civil Aviation Organisation)

49
Q

What is the ISA value for surface pressure

A

1013.2 hPa (29.92 in Hg)

50
Q

What is the ISA value for surface temperature at MSL?

A

15 degrees celsius

51
Q

What is the ISA lapse rate up to the tropopause?

A

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

52
Q

What is the ISA average temp for the tropopause

A

MS 56.5

53
Q

what is the ISA average density AMSL?

A

1.225 kg/m^3

54
Q

what typically happens around the ‘pauses’ with regards to temperature?

A

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

55
Q

what is the avg. temp at the stratopause?

A

0c

56
Q

what typically happens to the temprature in the stratosphere?

A

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

57
Q

what is the avg temp at the mesopause?

A

-90c

58
Q

what happens to the temprature in the mesosphere?

A

we see a drop in temps

59
Q

what happens to the temeprature in the thermosphere?

A

we see an inversion in temps

60
Q

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

A

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

61
Q

why can hot air hold more moisture?

A

because there are more gaps between air molecules

62
Q
A