Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A1 Paper 2 > Atmosphere > Flashcards

Atmosphere Flashcards

lectures 1, 2 and 3 (97 cards)

Start Studying
1
Q

weather vs climate

A

Weather - day to day condition of atmosphere - temperature, rainfall and wind

Climate - average weather conditions of a place, measured over one year or month

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

climate and weather determinants

A

Climate is determined by location on east/west coast of large continent
Weather is determined by local weather system, however it is not independent of local climate

San Fran, California, richmond, virginia - same lat on continent. same anual mean temp, mean wind direction in mid-lat is from west to east. san fran on west coast has a more maritime climate. due to continental influence - richmond has 4x larger anual temp range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

climate as a system of interacting spheres

A

Atmosphere
Hydrosphere
Cryosphere
Geosphere
Biosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

solar radiation value

A

342 W/m^2 - most important energy source for the climate system

need energy to drive circulation

geothermal 0.6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

black body

A

emission of radiation only dependent on temperature

perfect emitter and absorber

raditation that is absorbed will be converted into heat and increase bodys temperature

higher temp = more radiation emissions

radiative equilibrium when its at the temp where it emits as much as it absorbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

plancks law

A

intensity of emitted radiation as a function of temperature and wavelength
sun is an example
hotter object emits more radiation at shorter wavelengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

stephan-boltzman law

A

total energy emitted across all wavelengths -
E = T^4 x sigma
follows inverse square law and so receive
E-total / 4pi x distance^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

milankovitch cycles

A

eccentricity, obliquity, precession
eccentricity - how strong the eliptical shape is
obliquity - 41,000 years long, variations in angle between rotational axis and orbital plane. stronger = stronger seasons
precession - shortest cycles, determines when seasons occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

black body temp of earth vs actual temp

A

BB - 255K (equating incoming and outgoing energy)
actual - 288K

only absorbed radiation needs to be balanced (stuff that isnt reflected immediatley)

worked out using ((1−α)⋅S/4sigma) to the power of 1/4
​alpha = 0.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

white body

A

refelcts all radiation irrespective of wavelength
albedo of 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

solar radiation reflection

A

earths surface - brighter surfaces such as deserts or snow have most
cloud droplets and aerosol particles
gas molecules - rayleigh scattering
earth has albedo of around 0.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

solar constant

A

1368 w per m squared
dependent on total radiation emitted by sun, and sun-earth distance
earths surface receives 1/4 of solar constant per surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

radiation travelling through the atmosphere

A
  • transmission, no interaction (mostly solar)
  • scattering, gas molecule or particle, changes direction (only solar)
  • absorption, converted to heat, inc temp of matter or gas, then emit radiation (solar and terrestrial - gh effect)

scattering and apsorption (by greenhouse gases) are wavelength dependent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how much of 341 W/M^2 is reflected

A

102
can use albedo to work out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

absorption

A

2x amount of radiation is absorbed at surface than the atosphere
means that atmosphere is heated from below (important consequences for the vertical structure of the atmosphere)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

scattering

A

rayleigh scattering is wavelength dependent
shorter wavelengths (blue), scatter more efficiently, produces blue sky when looking away from the sun

water droplets and ice crystals in clouds are the most important scatterer in the atm

aerosols both scatter and absorb, needed as nucleation sites for cloud droplets to form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

clouds

A

water droplets and ice crystals
most important scatterer in atm
dominate planetary albedo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

UV

A

most of it is absorbed by ozone layer 20-25km

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

visible light

A

little absorption in ozone
main absorber is water vapor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

infared

A

terrestiral radiation
gases absorbing infared are greenhouse gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

net absorption

A

0.9W/m^2
due to theramal inertia of oceans and declining albedo

due to warming trend, ocean is not in thermal equilibrium with the atmosphere

thermal inertia - resistance of a system to changes in temp due to its ability to store heat
atmosphetre adjusts rapidly to changes (low heat capacity)

ocean has slower response
deep ocean even slower, slow mixing, heat capacity
prolongs effects of global warming (comitted warming)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

% of radiation emmited at surface that is absorbed by GHG or clouds

A

90%
then heats atmosphere
emits radiation up and down
10% emitted to space through atmospheric window

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

solar vs terrestrial radiation

A

atm is largely transparent for solar (66% of absorption of solar takes place at the surface)
opaque for terrestrial
absorption of T traps heat in atm
to achieve balance, more needs to be emitted at surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is responsible for absorption of longwave raduation in the atm

A

99% of atm is either nitrogen or oxygen
nitrogen does not absorb shortwave or longwave raditation
oxygen absorbs shortest wavelenght of UV (responsible for production of ozone)
neither contirbute to greenhouse effect - but do contribute to rayleigh scattering threfore albedo
water vapour, co2, methane, nitrous oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
radiative forcing
artificial imbalance or difference between outgoing and incoming radiation a quantitative estimate of how a change affects the earths energy balance (W/m^2) calculated under controlled conditions warming is positive forcing
20
methane and forcing
oxidises CO2 therefore water vapour and increase in ozone
21
aerosols
for most - scattering of solar radiationdominates producing cooling soot is an excetion, absorbs radiation therefore net warming aerosols produce more cloud droplets, making them smaller and brighter therefore cooling
22
thermostat effect
cloud feedback effect warmer climate, more ET, more clouds clouds reflect, cools, reduces intital warming overall, climate models suggest clouds have postive feedback
23
stephan boltzman law feedback
a negative feedback since any warming will lead to a very strong increase in the emitted radiation. This will quickly limit any further temperature increases. Thus, the fourth power in the Stefan-Boltzmann law restricts the temperature change that a forcing will produce.
24
What happens during evaporation and condensation?
Evaporation: More water molecules transition from liquid to vapour. Condensation: More water molecules transition from vapour to liquid.
25
What is saturation in the context of water and air?
Saturation occurs when there is a zero net flux of water molecules between liquid and vapour, meaning as many molecules evaporate as condense. The atmosphere is then in saturation with respect to liquid water.
26
What determines the saturation vapour concentration or saturation vapour pressure?
The saturation vapour concentration or pressure depends only on temperature.
27
How does the saturation vapour pressure over ice compare to that over liquid water?
The saturation vapour pressure over ice is lower than that over liquid water for temperatures below freezing.
28
What effect does the curvature of water droplets have on saturation vapour pressure?
The curvature of very small droplets increases saturation vapour pressure. However, for most cloud and all rain droplets, the surface behaves like a flat surface, so evaporation and condensation occur similarly to over a lake.
29
What is the saturation vapour pressure?
The saturation vapour pressure is the partial pressure at which air becomes saturated with water vapour. It represents the contribution of water vapour to the total atmospheric pressure.
30
How does saturation vapour pressure change with temperature?
The saturation vapour pressure increases approximately exponentially with temperature. It rises slowly at low temperatures and much faster at higher temperatures.
31
How does a 10ºC temperature drop affect saturation vapour pressure at warm vs. cold temperatures?
From 30ºC to 20ºC: Saturation vapour pressure drops significantly, leading to much more condensation and latent heat release. From 0ºC to -10ºC: The change in saturation vapour pressure is much smaller. This difference explains why cloud formation is more vigorous in the tropics than in polar regions.
32
What happens when saturated air cools, and why is this important?
When saturated air cools, it becomes supersaturated, causing condensation and cloud formation to restore saturation. In warmer regions, more vigorous condensation occurs, releasing more latent heat, which affects vertical temperature profiles in low and high latitudes.
33
What does the hydrostatic assumption state about pressure at a particular altitude?
The hydrostatic assumption states that pressure at a particular altitude is determined only by the weight of the fluid above that altitude.
34
In which systems is the hydrostatic assumption a good approximation, and where can deviations occur?
The hydrostatic assumption is a good approximation in the atmosphere and the ocean. Deviations can occur on small spatial scales, especially in the presence of topography.
35
equation used to calculate how pressure changes with altitude?
dP=-pgdz
36
How does pressure change in the ocean with depth, and what is the rate of change?
In the ocean, pressure changes linearly with depth. The pressure increases by approximately 1 bar for every 10 meters of depth.
37
What factors cause slight variations in ocean water density?
Ocean water density varies slightly due to temperature and salt content.
38
How does air density depend on pressure and temperature?
Air density is proportional to pressure and inversely proportional to temperature: Twice the pressure means twice the density. Twice the temperature means half the density.
39
How does atmospheric pressure change with altitude at constant temperature?
Atmospheric pressure changes exponentially with altitude. pressure halves every 5.5km
40
Where is most of the solar radiation absorbed, and how does this affect atmospheric heating?
Most solar radiation is absorbed at the Earth's surface, causing the atmosphere to be primarily heated from below.
41
Why are radiation and heat conduction insufficient to remove heat from the Earth's surface?
Radiation and heat conduction alone cannot transfer heat effectively upward, so vertical motion is necessary to carry heat through the atmosphere.
42
What process carries heat upward in the lower atmosphere, and why does it occur?
Convection carries heat upward because warmer air, which has a lower density than colder air, rises.
43
What dominates heat transfer at higher altitudes, and how does this differ from the lower atmosphere?
At higher altitudes, radiative processes play a larger role in heat transfer, unlike the lower atmosphere where convection dominates.
44
What does the first law of thermodynamics state about the internal energy of a gas?
The first law of thermodynamics states that the internal energy of a gas can change when heat is added externally or when the gas does work against the environment.
45
How is the internal energy of an ideal gas calculated?
The internal energy of an ideal gas is given by: Internal energy = Temperature × Heat capacity at constant volume Internal energy=Temperature×Heat capacity at constant volume Intermolecular forces like Van der Waals forces are ignored for an ideal gas.
46
What are some ways heat can be added externally to air in the atmosphere?
Heat can be added externally through processes like radiation absorption or the release of latent heat during condensation.
47
What is an adiabatic process in the atmosphere?
An adiabatic process is when air moves without exchanging energy with the environment. In a dry adiabatic process, we also ignore latent heat release or consumption due to phase changes
48
What is the dry adiabatic lapse rate
The dry adiabatic lapse rate is the rate at which temperature decreases with altitude during a dry adiabatic process.
49
What is the value of the dry adiabatic lapse rate, and how does it relate to altitude?
The dry adiabatic lapse rate is approximately 1 Kelvin per 100 meters, meaning the temperature drops by 1 Kelvin for every 100 meters of altitude increase.
50
Prompt: What does the dry adiabatic lapse rate represent in terms of atmospheric cooling?
The dry adiabatic lapse rate represents the strongest cooling that can occur in the atmosphere without generating vertical motion or cloud formation.
51
What happens to air as it rises and reaches saturation?
As air rises and cools, the saturation vapour pressure drops. When saturation is reached, further cooling causes cloud formation, which releases latent heat from condensation.
52
How does latent heat release affect the lapse rate of rising air?
Latent heat release heats the air as it rises, reducing the dry adiabatic lapse rate to form the saturated adiabatic lapse rate (or moist adiabatic lapse rate).
53
What is the relationship between the saturated and dry adiabatic lapse rates?
The saturated adiabatic lapse rate is smaller than the dry adiabatic lapse rate because latent heat release reduces the rate of cooling as air rises.
54
Why does the saturated adiabatic lapse rate approach the dry adiabatic lapse rate at colder temperatures?
Since the saturation vapour pressure changes more slowly at colder temperatures, less latent heat is released. As a result, the saturated adiabatic lapse rate becomes closer to the dry adiabatic lapse rate in colder conditions, such as in polar clouds.
55
How does temperature affect the difference between the lapse rates in tropical and polar clouds?
In tropical clouds, the temperature decreases more slowly with altitude because of higher latent heat release. In polar clouds, less latent heat is released, so the temperature drops faster, approaching the dry adiabatic lapse rate.
56
What is the saturation mixing ratio?
The saturation mixing ratio is the mass of water vapour per mass of air at saturation. It changes depending on temperature and affects the amount of latent heat released.
57
What is atmospheric stability?
Atmospheric stability describes whether air will move vertically on its own. In unstable conditions, air rises freely due to buoyancy. In stable conditions, air resists vertical movement unless forced.
58
What determines whether air will rise or remain stable in the atmosphere?
The comparison between the observed atmospheric lapse rate (γ) and the dry adiabatic lapse rate (γdry): If γ > γdry, the atmosphere is unstable. If γ < γdry, the atmosphere is stable.
59
What happens when the observed atmospheric lapse rate (γ) is larger than the dry adiabatic lapse rate (γdry)?
The air parcel cools less (at γdry) than the surrounding atmosphere. This makes the parcel warmer and less dense, causing it to rise due to positive buoyancy. This is an unconditionally unstable situation.
60
What is an example of an unconditionally unstable situation in the atmosphere?
Thermals near the surface, where strong surface heating creates pockets of air that become buoyant and rise within the atmosphere.
61
What happens when the observed atmospheric lapse rate (γ) is smaller than both the dry adiabatic lapse rate (γdry) and the saturated adiabatic lapse rate (γmoist)?
The atmosphere is unconditionally stable. Vertically displaced air cools more than its surroundings, whether it follows the dry or saturated lapse rate, and it sinks back to its original position due to negative buoyancy
62
What characterizes an unconditionally stable atmosphere?
An atmosphere is unconditionally stable when the observed lapse rate is less than both the dry and moist adiabatic lapse rates, making displaced air colder and denser than the surrounding air, leading to its return to the original position.
63
What is an example of an unconditionally stable atmospheric condition?
Temperature inversions near the surface, where radiative cooling at night creates colder temperatures near the ground than higher up, resulting in a stable atmosphere.
64
What happens when the observed atmospheric lapse rate (γ) lies between the dry adiabatic lapse rate (γdry) and the moist adiabatic lapse rate (γmoist)?
his describes a conditionally unstable atmosphere. Initially, the lifted air cools dry adiabatically and is stable. Upon reaching saturation, it cools at the moist adiabatic lapse rate, leading to instability because the atmospheric lapse rate is larger than the moist lapse rate.
65
What is required for instability in a conditionally unstable atmosphere?
The occurrence of saturation is required for instability, as the air parcel then follows the moist adiabatic lapse rate, creating positive buoyancy.
66
What type of clouds form under conditionally unstable conditions?
Vertically developing or convective clouds, such as thunderstorm clouds, form under conditionally unstable conditions.
67
What is the typical lapse rate in the lower atmosphere under conditionally unstable conditions
he lapse rate is close to the moist adiabatic lapse rate, around 0.65 K per 100 metres for surface temperatures near the global mean.
68
What is atmospheric convection, and how is it classified?
Atmospheric convection refers to vertical motion due to positive buoyancy caused by local instability. It is classified as: Dry convection: No clouds involved. Moist convection: Clouds form, and latent heat release occurs, which is crucial for atmospheric heating.
69
Why is moist convection important?
Moist convection is important because it: Heats the atmosphere through latent heat release. Dominates precipitation in the tropics and mid-latitude summers.
70
What roles does convection play in the atmosphere besides heating?
Removes instability by redistributing heat and moisture vertically. Transports momentum and pollutants vertically.
71
Why is there little net transport of mass by atmospheric convection?
Convective updrafts are largely compensated by downdrafts in nearby regions, resulting in very little net mass transport. This makes convection distinct from the atmospheric mean circulation.
72
What is the troposphere, and what characterizes its temperature profile?
he troposphere is the lowest 12 km of the atmosphere, characterized by: Vertical mixing through convection. A mean lapse rate of 0.65 K per 100 m. It ends at the tropopause.
73
What causes the temperature increase in the stratosphere?
In the stratosphere, temperature increases due to: Absorption of solar radiation by the ozone layer. This layer is extremely stable and ends at the stratopause (~48 km altitude).
74
What defines the mesosphere, and how does its temperature change?
The mesosphere lies between the stratopause and mesopause (~80 km altitude). Temperature decreases with altitude. Dominated by dry adiabatic processes, with some heating from radiation and atmospheric waves.
75
Why does temperature rise in the thermosphere?
In the thermosphere (~80 km and above), temperature rises due to: Absorption of solar radiation at very short wavelengths by oxygen. At higher altitudes, air density becomes so low that temperature is less well defined.
76
How does radiation transport heat in the atmosphere?
Radiation transports heat through: Emission (causes cooling). Absorption (causes heating). Radiation can also be scattered or transmitted, influencing where absorption occurs.
77
What is turbulence, and how does it transport heat?
Turbulence is caused by friction at the surface. Produces turbulent eddies that mix heat vertically and horizontally. Dominates in the boundary layer (lowest ~1 km of the atmosphere). Transports heat that enters the atmosphere via surface conduction.
78
What is advection, and how does it transport heat?
Advection involves the horizontal transport of air over large scales (kilometers and above). Horizontal convergence/divergence leads to vertical transport. Driven by temperature differences and reduces temperature gradients. Includes heat transport from equator to poles by global circulation.
79
cirrus clouds
tend to warm - greenhouse > albedo
80
deep cumulus clouds
radiatively neutral
81
stratus clouds
tend to cool albedo > greenhouse
82
what effects the amount of solar radiation received at the earths surface
latitude effect - shallower angle towards poles, radiation illuminates a larger area sun angle throughout the day seasons - summer tilted towards sun, days are longer further away from equator
83
most radiativley relevant components of atm
occur in very small concentrations water vapour - highly variable amounts, half a percent avg
84
CO2 absorption
CO2 absorbs nearly all radiation at certain IR wavelenghts adding more CO2 broadens the band of wavelengths that are absorbed more co2 means the altitude at which radiation escapes to space increases - higher in the atmosphere = colder = less energy emitted (stephan boltzman) therefore planet warms at surface to rebalance the outgoing and incoming energy
85
water vapour effect
positive feedback a warmer atm = higher water vapour concentrations required before clouds can form = more WV in atmosphere acting as a GHG, amplifying the warming
86
Ahrens 2009
cite for - - general atmospheric dynamics - cloud formation - mid latitude cyclones
87
Meliers et al 2015
cite for long term climate transitions and trends
88
palmer 2017
atmospheric structure and processes GHG, feedbacks radiative forcing
89
Bigg 2003
ocean atmosphere interactions currents, AMOC
90
andrews 2010
physics behind atm processes fluid dynamics of atm atm circulation and jet streams
91
what is the hydrostatic assumption
the pressure at a particular altitude is only determined by the weight of a fluid above that alititude very good approximation - climate models used

A1 Paper 2 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions