The Climate System Flashcards
(78 cards)
1
Q
What is a system?
A
- A set of interacting objects of which there are three elements
2
Q
What are the three elements of a system?
A
1) A set of components
2) A flow of energy
3) A process for internal regulation of their functioning via positive or negative feedback
3
Q
What is an open system?
A
- Allows energy and mass to pass across the system boundary
4
Q
What is a closed system?
A
- Allows energy but not mass across its system boundary e.g. earth
5
Q
What are the five components of the climate system?
A
- Atmosphere (all gases and particulates)
- Hydrosphere (all liquid water)
- Cryosphere (all frozen water)
- Biosphere (flora and fauna)
- Lithosphere (surface and subsurface)
6
Q
Describe the atmosphere
A
- Most unstable and rapidly changing of the climate system components.
- Changing composition and subsequent climate change is of considerable concern.
- Extreme events
7
Q
Describe the greenhouse effect in relation to the atmosphere
A
- Natural process that keeps the earth 15 degrees above freezing.
- Without it the global temperature would be -18 degrees.
- Human activity is increasing the greenhouse effect to an amount that is harmful for the atmosphere.
8
Q
What makes up the hydrosphere?
A
- Oceans, surface and subsurface water
- Has a circular system known as the Hydrological cycle.
9
Q
What makes up the cryosphere?
A
- Mountain glaciers, ice sheets, snow, sea ice, ice sheets, permafrost and frozen ground
- Consists of liquids in solid form
10
Q
Describe an area of glacier retreat?
A
- Cascade mountains- glaciers been retreating since 1928
11
Q
What is an important part of the biosphere?
A
- The carbon cycle
12
Q
What is the energy source for our climate system?
A
- The sun
13
Q
What is the radiation spectrum?
A
- Shows what kind of radiation reaches the earth.
- Radiation can be in the form of short or long waves.
- The visible radiation range is the radiation which we can with the naked eye and is between 0.4-0.8 micrometer
14
Q
What is the Stefan Boltzmann Law?
A
- Describes the amount of energy emitted by an object
15
Q
In radiation what does a lower temperature mean?
A
- Less temperature is emitted- proportional
16
Q
What is Wein’s law?
A
- Describes the relationship between temperature and wavelength
- Sun surface temperature is 6000 degrees, Earth’s is 15 degrees- shows that the sun emits more energy.
17
Q
What do short waves mean?
A
- More energy e.g. The sun
18
Q
What do long waves mean?
A
- Less energy e.g. Earth
19
Q
What are orbital varies?
A
- Things which affect radiation/energy that reaches the Earth’s surface e.g. Different distances from the sun and earth at different times of year.
20
Q
What is obliquity?
A
- The tilt of the Earth’s axis
21
Q
Give an example of a cycle
A
Milankovitch cycles
22
Q
What happens to the energy from the sun?
A
- It can be scattered, absorbed or reflected.
23
Q
How much solar radiation is absorbed by the Earth’s surface?
A
- 50%
- 20% reflected by clouds, 19% absorbed by clouds, 4% reflected from surface
- 6% reflected by atmosphere
24
Q
What happens to short waves?
A
- A shortwave received at the surface is made up of direct (28) and diffuse (23) components.
- Direct passes uninterrupted through the atmosphere.
- Diffuse is scattered or reflected downwards but does eventually make it to the surface.
25
What happens to long waves?
- Amount of long waves at the surface is the difference between the long wave received at the surface (96) and the amount of long waves emitted from the surface (117).
96-117= -21
26
How do you work out the net radiation?
- To find the net radiation we take the net shortwave radiation (Incoming SW-Reflected SW) and add it to the net long waves radiation (Incoming LW- Reflected SW).
27
What is the equation for net radiation?
- Q*= K*+ L*
| 30= 51 (28+23) + -21 (96-117)
28
What would happen if the earth didn't get rid of all it's latent and sensible heat?
- It would heat uncontrollably up to 200 degrees per day
29
What is albedo?
- Shortwave radiation reflectivity which determines incident shortwave radiation at the surface.
- Greater amounts of snow and ice= greater albedo= greater reflection
30
What happens when there is a build up of energy?
- Has to be gotten rid of
- Energy surplus in equatorial regions but a deficit in polar regions.
- Must be evened out.
- Mechanism for redistribution is global atmosphere circulations and also ocean circulations.
31
What is important with regards to the effect of net radiation?
- the nature of the surface has a big impact
| - is the surface wet or dry?
32
What is the global distribution of albedo?
- High amount of albedo in the region of the equator
33
How do we get the weather map result?
- The global atmospheric circulation
34
What is wind?
- Transfer of mass (air) from one place to another
35
What is the pressure gradient?
- The difference in pressure
- Cold air sinks (high pressure)
- Hot air rises (low pressure)
36
What is the effect of pressure gradient force on wind speed?
- Much steeper difference in pressure means there is a much greater wind speed.
37
What is the Coriolis force?
- Direct result of the rotation of the earth
- Increases away from equator
- Causes wind force to be deflected
- Greater the wind force, the greater the Coriolis effect
38
What is geostrophic wind?
- Forces tend to balance each other in the upper atmosphere
- 'free' atmosphere- free from Earth's affects
- Means that wind is running parallel between low and high pressure
39
What is gradient wind?
- The product of the Coriolis, Centripetal and pressure gradient working together
- The Coriolis effect and the Centripetal force balance each other out
40
What is surface wind?
- Balance between pressure gradient, Coriolis, Centripetal and friction forces.
- Earth's rough surface creates friction slowing wind down and deflecting it.
- Land surface friction much greater than over oceans.
41
What are the ideas about a simple circulation in the atmospheric circulation?
- The earth is not rotating in space
- The earth's surface is composed of similar materials
- The global reception of shortwave and long waves cause a temperature gradient of hotter air at the equator and colder air at the poles.
- These points are not necessarily true
42
What is the reality of the earth?
- Different cells
- Rotating earth is the reality.
- Big effect on wind and atmospheric circulations compared to straightforward patterns if the earth didn't rotate.
43
What are the different wind patterns?
- Polar easterlies
- Westerlies
- Northeast trades
- Southeast trades
- Westerlies
- Polar easterlies
44
Describe the three cell model of atmospheric circulation
- Polar cell, Ferrell cell, Hadley cell, equator, mirror image in Southern Hemisphere
- At the equator the convergence of the north trades and south cause ascension.
45
Describe seasonal heating and circulation
- Sun can be on either side of the equator
- Impacts on tropical convergence zone
- Westerly impacts on UK storms and wind
46
What is important to note about circulation?
- Circulation patterns are vertical as well as horizontal
47
What is the upper flow mostly westerly associated with?
- Hadley, Ferrell and polar cells.
| - In the upper atmosphere winds are all westerly because there is no Coriolis effect.
48
Describe some of the significant features of the westerly winds?
- Upper westerlies flow entirely around the globe
- Also have a tendency to meander
- Nature, size and spacing of these meanders may vary depending on the weather experienced in the mid-latitudes
- Meanders are known as Rossby Waves
- Within the upper westerlies strong ribbons of wind form which are known as jet streams.
49
What is a Rossby wave?
- Term used to describe the meanders in the upper westerly circulation
50
What is a jet stream?
- In the upper westerlies, strong ribbons of wind form and this is what this means.
51
What is the driving force behind Rossby waves?
- Changes in the Coriolis force involving latitude
52
What is the formula for calculating the absolute vorticity of Rossby waves?
```
Absolute vorticity (n) = geostrophic relative vorticity + Coriolis force
- n is a constant value and is always the same, so the other variables must change to compensate a change in the other.
```
53
What is absolute velocity?
- A measure of the total spin of everything on Earth
54
Describe jet streams
- Relatively narrow bands of wind in the upper westerlies (troposphere) that blow from west to east at altitudes up to 15000m.
- Surface temps determine the location of jet streams.
- Jet streams follow the boundaries of hot and cold air. As these are most pronounced in winter, jet streams are the strongest for both the north and Southern Hemispheres.
55
How do surface temperatures affect jet streams?
- A greater difference in temp leads to a faster wind velocity inside the jet stream.
- This abrupt change causes a large pressure difference which forces the air to move.
56
What causes jet streams?
- Combination of planet's rotation and atmospheric heating
- Results from latitudinal and vertical large pressure gradients.
- Combination of temperature and pressure differences and the Coriolis force creates acceleration of winds into the jet stream.
57
What is the polar jet stream?
- Cold polar air flowing down from the north which then meets the warmer air mass over the US causing the polar jet stream to form.
58
What is the subtropical jet stream?
- Ascending air in equator flows towards the poles after reaching the tropopause.
- It is deflected by the Coriolis force during its path toward the poles and becomes a westerly wind.
- Air blows rapidly from west to east.
59
What is the global pressure distribution?
- L, H, L, H from the equator to the poles
60
What are air masses?
- Large volumes of air with homogeneous thermal moisture and stability characteristics
- Formed when air sits over the ocean or land for several days.
61
What is interesting to note about the properties of air masses?
- They all have different physical properties e.g. Hot/cold, moist/dry
62
What are the three major types of front?
1) Cold
2) Warm
3) Occluded
63
What is a front?
- Essentially acts like a barrier
64
What happens in cold fronts?
- Warm air and cold air meet and warm air is forced upwards forming clouds and sometimes thunder storms
65
What happens in warm fronts?
- Warm air is advancing.
- Warm air is not dense enough to push the cold air and so the warm air slides over the cold air instead.
- Eventually this forms clouds
- However these are stratus clouds which are very thin and form over large distances.
- Here rain will fall quite downwind of warm front boundary (unlike cold fronts)
66
What happens in occluded fronts?
- Very cold advancing air meets receding cold air.
- Essentially this is when a cold front catches up with a warm front.
- Large amounts of rainfall over a large geographical area are associated with occluded fronts.
67
Describe cyclogenesis
- Cold air from north meets warm air from south and begins a rotation
- High pressure comes down to surface and vice versa
- In northern hemisphere mid-latitude cyclone paths generally go from east to west.
68
Describe hurricanes
- SST must be in excess of 26.5 C
- Lots of energy and moisture being transformed in the atmosphere.
- Needs to be limited vertical wind sheer which means low difference between wind speed at surface and mid and upper atmosphere.
- Tropical depression may form from multiple major thunderstorms joining together in an area of low pressure.
- A tropical storm may then form and as SST continues to drop it will become a hurricane when it reaches 32 mph
69
Describe ocean role
- Huge capacity to slow things compared to the atmosphere e.g. CO2, heat, water etc
70
What is the relationship between the oceans and the atmosphere?
- Exchange as much heat, water and CO2 between them as each transports horizontally.
- Water has a high specific heat capacity- 4x more energy to raise temperature of water than air.
- Oceans absorb half of CO2 produced from fossil fuels but when CO2 dissolves in seawater it forms carbonic acid which makes the oceans more acidic.
71
Describe the ocean circulation
- Ocean circulation generally mirrors the atmospheric circulation (wind patterns).
- Ocean guiserers- large circular ocean circulation which helps to transfer surplus energy to areas of deficiency.
72
Describe the Ekman drift
- Causes cool water to be upwelled
- Climate outcome is very dry because upwelling reduces evaporation
- Also impacts on minerals which can potentially shut down the food chain.
73
What is the weather?
- Day to day variations
74
What is the climate?
- More long term than the weather
75
What are the characteristics of climate variability?
- Ranges over many time and space scales
- Small scale phenomena- wind gusts etc
- Large scale droughts etc
- Fluctuations- seasonal, annual, decades
- Longer time scale phenomena associated more with the the atmospheric circulations.
76
Describe teleconnections?
- Persistent atmospheric and ocean features can occur simultaneously over vast, seemingly unrelated parts of the globe.
- May result in abnormal weather, temperature and rainfall
- Climate anomalies in different places may be opposite e.g. Hot, cold but are still relaxed
- Teleconnections are like a bridge
- Lots of different examples of teleconnections e.g. El Niño Southern Oscillation.
77
Describe the North Atlantic Oscillation...
- Variation in pressure between Iceland and the Azores
- Iceland normally has low pressure and Azores usually high.
- Positive phase means there is very intense low pressure in Iceland and very high in Azores results in north easterly storms with wet conditions in Northern Europe and dry conditions in Mediterranean.
- Negative phase is a reversal of this.
78
Describe Enso
- El Niño and La Niña represent opposite extremes of ENSO cycle
- Each episode lasts 9-12 months
- Form during June- August, peaking December- April, dying around May
- Can last up to 5 years
- Generally occurs every three to five years
- Can cause many issues for wildlife etc
- Reversal of climate conditions with El Niño
- Extreme intensification of conditions with La Niña
