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Climate Change > Frist Half > Flashcards

Frist Half Flashcards

1
Q

what is the difference between climate and weather?

A

Weather = state of the atmosphere at a given time

climate = avg weather over a long period of time (typically 30yrs)

  • it is a statistical measure and does not typically vary much
  • climate systems also includes the oceans, cryosphere, vegetation and lithosphere as well as the atmosphere
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2
Q

two methods of weather observation

A

global surface weather stations

upper air radiosonde (balloon) stations in north america

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3
Q

surface weather stations “stevenson screen”

A

white box about 1 m off the ground

measures humidity, temp, pressure and wind

white to minimize overheating

vents to allow air flow

anemometer is 1m above ground to measure wind

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4
Q

weather balloons

A

measure the lowest 30km of the atmosphere twice a day around the world

measures temp, moisture, wind and these are used to create weather maps at diff altitudes

when the balloon reaches 30km the balloon bursts and the measuring package is dropped

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5
Q

4 different observations that show climate change is actually happening

A
  1. global annual mean surface air temp
  2. global mean sea level
  3. arctic summer sea ice extent
  4. atmospheric carbon dioxide concentration and ocean acidification
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6
Q

evidence 1: global mean surface temp

A

in the last 50yrs the global surface temp has increased by 1 degree celcius

warming hiatus from 2002 to2012

last 5 years have the warmest since 1880

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7
Q

evidence 2: global mean sea level

A

increasing at about 3.4mm/yr = 34 cm/ 100yrs

it is going to increase no matter what but it can be kept to a minimum

better indicator of climate change because it better indegrates on a global scale the effects of increased radiative forcing

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8
Q

two reasons why the sea levels are rising

A
  1. Melting land ice (not sea ice in the north pole) in greenland, antarctica and glaciers
  2. thermal expansion - as ocean waters heat up the water molecules move more and therefore take up more space, increasing volume without increasing mass
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9
Q

evidence 3: arctic sea ice extent

A

loosing 0.83 million square km per decade

lg amount of inter-annual variability

in the linear decline observed in the las 40yrs continues, the arctic will be ice free in 50 years

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10
Q

evidence 4: increasing atmospheric CO2 and its effect on ocean acidification

A

increasing CO2 in environment warms climate and acidifies the oceans

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11
Q

what happens to atmospheric pressure and air density with height?

A

both decrease exponentially

the decreasing air pressure with height creates an upward pressure that balances the downward force of gravity - this is called hydrostatic pressure

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12
Q

the atmospheric layers and their boundaries

A

troposphere: closest to the earth, active weather is here, clouds and precipitation, weather impacted by earths surface

equatorial tropopause= boundary

stratosphere: also the ozone layer, clear, very dry and stable
- the ozone layer protects us from harmful UV radiation by absorbing it ( this is why temp actually increases with height in this layer)

stratopause = boundary

mesosphere: temp decreases with height bc of ozone heating

mesopause

thermosphere - extends to space where the thermopause in theory exists

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13
Q

chemical composition of air

A 
constant gasses: 
Nigtrogen
Oxygen
argon
neon
helium
hydrogen
variable gasses:
water vapour
carbon dioxide
nitrous oxide
carbon monoxide
chlorofluorocarbons
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14
Q

ozone

A

this gas is a minor player in climate change

most of it is found in the stratosphere where is absorbs harmful UV radiation from the sun - doesn’t reach earths surface

ozone in the troposphere is considered to be air pollution and is formed photochemically from nitrous oxides ( as a result of fossil fuel burning)
- ground level ozone is harmful to humans and plants

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15
Q

residence time

A

average lifetime of a molecule in the atmosphere

total mass in reservoir/ mass outflow rate

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16
Q

issue with residence time for carbon dioxide

A

according to the formual it is only 5 years

however the CO2 were adding is nowpart of the total climate system and goes intoplants and oceans fora few years and then comes back into atm so were not permanently removing it

reality is it takes hundreds of years to actually remove it

only way to get rid of it completely is to deposit it at the bottom of the ocean on the sea floor

17
Q

hydrological cycle

A

this is the water cycle

evaporation/condensation transfer large amount of heat from the surface to air

then you get land percipitation

also have soem evaporation and transpiration

percoaltion = water flows into groud then ground water flows back into ocean

18
Q

important facts about the ocean

A

71% of earths surface = ocean

ocean = 97% of earths water

avg depth is 3.7km deep
- deepest point is 11km

important for climate change because of their ability to store and transport huge amounts of energy and to delay temperature response because of its huge heat capacity

19
Q

what is the temperature at the bottom fo the ocean and why?

A

bottom of ocean is very cold

the thermocline is the layer where the ocean temp decreases rapidly with depth

the deep ocean is cold bc the water source is the polar sea surface
- the densest water will be cold and salty and therefore sinks to the bottom of the ocean

20
Q

properties of electromagnetic spectrum

A

amplitude

wavelength

frequency

waves are described based on specifying wavelengths or frequency

21
Q

thermal radiation

A

radiation emitted by substances based on its temperature

the hotter the material the more radiation is emitted
- material gets hotter, radiaiotn being emitted shifts to shorter wavelengths

all matter emits electromagnetic radiation in accordance to its temperature

most solid surfaces and liquids are able to absorb and emit radiation at all wavelengths efficiently

22
Q

black bodies

A

the material is able to absorb and emit radiation at 100% efficiency

gasses do not act as black bodies because they absorb and emit at very specific wavelengths

23
Q

infrared radiation (IR)

A

invisible radiation with wavelengths that are longer than the visible red wavelengths

2 types for climate studies: solar infrared, terrestrial

24
Q

solar infrared

A

near-infrared or shortwave infrared radiation

emitted by the sun

makes up approx. half of solar radiation

25
Q

terrestrial infrared

A

longwave infrared radiation

emitted by the earths surface and atmosphere

strongly absorbed and emitted by greenhouse gasses and clouds in the atm

26
Q

which electromagnetic waves can transmit through the earths cloudless atm?

A

some UV

most visible

some infrared

some microwaves

some radio

27
Q

energy conservation for the climate

A

when energy in = energy out the earth will have a constant energy content and constant global avg temperature

28
Q

albedo

A

fraction of incoming radiaiton that is reflectid by an object

an albedo of 1 = all incoming radiaiotn is reflected

an albedo of 0 = no radiaiotn is relfected, it is all absorbed

average planetary albedo is 0.3 (30%)

29
Q

three factors that determine the globally averaged surface temperature

A
  1. amount of incoming solar radiation - sun’s surface temperature + distance from earth
  2. albedo of the earth - determined by brightness of clouds/surface
  3. greenhouse factor - determined by amount of greenhouse gasses and clouds

predicted planetary temp is -18 but the actual observed surface temp is 15

30
Q

energy imbalance

A

this will occur when some of the outgoing terrestrial infrared radiation is reduced or blocked

out going terrestrial radiaiton gets progressively more blocked as teh greenhouse gas concnetration increases
- this is because greenhouse gasses absorb and emit at certain terrestrial infrared wavelengths

31
Q

what happens if the atm becomes more opaque at certain wavelengths?

A

the radiation at those wavelengths wil not be able to penetrate as afr in teh atm

addition of more greenhouse gasses is making the atm more opaque at many of the terrrestiral wavelenghts

32
Q

how adding greenhouse gasses warms the earth

A

as the greenhouse gas concentrations increase it makes the atm more opaque to certain wavelengths of terrestrial radiation

the penetration depth of the infrared radiaiton is reduced (i.e. the infrared radiaiton cannot travel as far in the atm)

as a result, more of the outgoing radiaiton escaping to space originates from higher in the atm where it is colder

but a colder srouce meits less thermal radiation

the result is that the earth is emitting less terrestrial infrared radiaiton back to spcae bc of the extra greenhouse gases

net incoming solar is the same - earth is accumulating energy which will drive up the global avg temp

33
Q

energy imbalance at the top of the atm

A

earth has less terrestrail radiaiton outgoing to space bc the atm is more opaque to terrestrial infrared

net incoming solar energy is larger than outgoing - total energy content of the earth is increasing (temp increasing)

global warming is happening bc the extra greenhouse gases are making the atm less transpartnt in the infrared

acuumalted energy goes toward oceans (94%), melting ice sheets (3%), heating the land (3%)

34
Q

achieving a new energy balance: stabilize greenhouse gases

A

as the heat content fo the earth increases: air, ocean and land temps will all increase, gradually increasing the amount of terrestrial infrared radiation escaping to space

results in eventually the outgoing terrestrial infrared energy becoming equal with incoming solar energy

energy balance is re-established however teh new steady state is at a hgiher surface temp

35
Q

how is heat related to warming?

A

heat capacity

if we add the same amount of heat to two systems with different masses, the larger system will have a smaller temperature increase and the change will occur slowly

rate of temperature increase depends on heat capacity

36
Q

how is the current energy surplus the earth is experiencing being used up?

A

heating the oceans (94%)

melting ice sheets and glaciers (3%)
heating the land and sub-surface (3%)

37
Q

how does the ocean cause a time delay in climate system and a reduction in the temperature response?

A

oceans have a large heat capacity - able to absorb a lot of heat without increasing the temperature much

also explains the difference between a maritime climate and continental climate

Climate Change (1 decks)

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