fundamentals of climate
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what are the components of the climate system?
atmosphere ocean - including its biosphere land - including its biosphere cryosphere - glaciers, ice caps, sea-ice, seasonal snow cover
koppen climate classification determines variation of climate with location and is broadly determined by….
latitude, altitude, disatnce from the ocean, seasonal variation of temp and rainfall
temperature falls strongly with height in the…
troposphere and increases again in the statosphere
what temperature emits radiative energy?
absolute 0 (0 K or -273 degrees celsius) which includes ME!
what is the perfect emitter of radiation called?
a black body
what is total energy of the sun emitted per second per metere-squared?
T~5800 K
how much energy do we emit? (T - K measurement units )
T~300 K
What are good emitters and absorbers of thermal infrared radiation?
clouds and many gases in the atmosphere such as CO2 OR H2O
what amount of energy is available to warm the earth and power the earths system?
340 W m-2
what amount of sun is reaching the earth? (totar solar irradiance - w m-2)
The amount reaching the Earth is called the “Total Solar Irradiance” So ≈ 1360 W m-2
is all of the suns energy absorbed by the earth and if no where does it go?
Not all this energy is absorbed by the Earth. Satellite observations show that 30% of it is reflected back to space by clouds (≈15%), the Earth’s surface (≈10%) and atmospheric gases (≈5%)
what is the 30 percent of energy which is not absorbed by the earth and is reflected back to space by clouds, the earths surface and atmospheric gases known as?
planetary albedo - normally given as a decimal fraction, 0.3
what amount of energy is absorbed by planet earth? (W m-2)
240 W m-2
where is the earths emission and why?
in the thermal infrared - because its relatively cold
what percent of what is emitted by the surface reaches space?
60 percent This is because greenhouse gases and clouds absorb the infrared radiation emitted by the surface; because the atmosphere is cooler than the surface, the amount it emits is less than the amount it absorbs And some of the atmospheric emission is down to the surface, which helps keep the surface warm
how much of the suns energy reaches the surface?(fraction ish number)
around two-thirds – the role of the greenhouse gases is to essentially “trap” that energy in the system, keeping the surface warmer than it otherwise would be
atmosphere is made up of 99 percent of..
nitrogen and oxygen These are simple molecules that are ineffective at absorbing thermal infrared radiation
which main greenhouse gases are responsible for the natural greenhouse effect?
h20 - 60 percnt co2 25 percent other gases…..ozone, methane nitrous oxide
what percent do clouds contribute of trapping thermal infrared radiation?
around 20percent
which parameters determine the earths energy balance?(3 things)
the total solar irradiance , the planetary albedo and the concentrations of greenhouse gases, such as CO2 If any of these change they lead to an imbalance in the Earth’s energy budget (called “radiative forcing” – see next week) and the climate system responds (“climate change”) to try to re-establish balance
what is an imbalance in the earths energy budget called
radiative forcing
signs of radiative forcing determine whether the climate system….
warms or cools
changes in components of the climate system which influence the earths energy budget are called..
feedbacks
what do feedbacks do?
they can either amplify or reduce the size of climate change