The atmosphere and Ocean lecture 1

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The atmosphere and oceans contrast with the other components of the Earth System in the sense that they are
rapidly moving fluids. It is this behavior that makes them so important to understand, because they link the other components of the Earth System together.
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No water, no life. Water is provided by the
ocean and atmosphere.
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No movement of air or water, no dispersal of simple organisms, or
chemistry required/produced by the biosphere
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And of course the atmosphere and ocean play many important roles in the Earth System irrespective of their interaction with the other components. E.g.
The atmosphere regulates temperature, The ocean circulation maintains ½ the planets biology
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It is clear from looking at the different temperatures of planets in our solar system that greenhouse effects operate – on a massive scale Clearly the differences in temperature of Mercury Venus and Earth
can not be explained simply by their distance from the sun each has a greenhouse Venus’ atmosphere is 97% CO2, ours is 0.04% CO2
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This hits a cross section of earth – a disk - which we can describe with the equation for a circle
– Pi*radius squared - This gives is the total amount of the sun’s energy hitting our planet
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We use a disk rather than dividing the energy across the surface of a sphere (the earth’s surface) because where the earth’s surface is not perpendicular to the incoming radiation, that energy is
diluted’ over a larger area – i.e. 1m2 of the surface at higher latitudes receives less than 1366W/m2 This gives us the total amount of the sun’s energy arriving at our planet
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Over a day this energy is spread over the whole surface of the planet, so we can divide that number by the area of a sphere
– 4*Pi*radius squared - This gives us the average energy hitting a square meter of the earth’s surface
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What are watts?
342W is a flow of energy approx. equivalent to eating a mars bar every hour continuously
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But about 1/3rd of that energy is reflected by reflective surfaces
like ice So the total energy being absorbed by the earth is on average 240W/m2
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The relationship between temperature and emission of radiation is described by the
stephan boltzman constant multiplied by the 4th power of temperature – the line shown here
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Average temp should be :
-18c but its actual 14 c
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The energy is still all lost (at least in a preindustrial atmosphere), but from higher up in the atmosphere
the surface temperature is kept warmer by greenhouse gasses
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The greenhouse effect is caused by the different ways in which the radiation emitted by the sun, and
the radiation emitted by the earth interact with the atmosphere
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cloudy nights are warmer than
clear nights
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By absorbing the radiation the atmosphere will warm up, and that
radiation will not directly escape
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The main absorbers of outgoing ‘longwave’ radiation
We see that water vapor is actually the most important greenhouse gas – but after that it is CO2
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Average temp
32c
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absorption of radiation by molecules is a bit messy, and there is partial absorption at the edges of these peaks – it is in these wavelength bands that
CO2 will be absorbing more radiation in the future
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An important consequence of this is that you get more warming for a given CO2 concentration increase at lower CO2 concentrations – and the temperature increases by about the same amount each time you
double the concentration of CO2 in the atmosphere
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This is also why methane is such an important greenhouse gas
- Concentrations of methane are so low that an increase in concentrations will absorb more radiation in every wavelength band that it covers
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Aersols
n2, 02 etc
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Then over more recent time – the 800,000 years, we have very good estimates of atmospheric CO2 concentrations from ice-core bubbles.
this tells us clearly that there is a strong carbon cycle that reacts to and drives changes in climate And of course more recently atmospheric greenhouse gas concentrations have been increasing very rapidly because of human activity
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But we should be aware that continuous observations are only
available for the recent past
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RCP 8.5
highbaseline
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Energy supply
26% greenhouse gas , industry 19% and waste only 3%
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Aerosols are probably the second most important component after CO2 The can form from:
Naturel – volcanic, dust of deserts, wildfires Anthropogenic processes – product of fossil fuel burning
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Magnitude of effect that they have on climate is not tied down precisely
Because interaction with system complicated
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Aerosols produce spatially heterogeneous forcing
and differential heating is what causes weather (to change)
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And largely because of the problems associated with air pollution – for example the smogs in large Chinese cities We expect the concentrations of most aerosol species to
fall rapidly in the future
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Radiation arriving from the sun at the top of our atmosphere averages about: 1350W per m2 or about 340W per m2 at the Earth’s surface…
…or 1 kettle constantly boiling over every 6m2 of the planet
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Whilst cycles in the suns activity, related to sunspot activity do correlate in part with recent warming, this variability is tiny This is not to say that there might be some more subtle effects of this variability
for example this variability happens in specific wavelengths, which it has been suggested might have an impact on stratospheric chemistry and therefore perhaps even episodes of extreme weather in Europe But globally there is no mechanism known which
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This SO2 acts just like industrial SO2, and oxidises to particles of sulphate aerosols, effecting climate in all the ways we’ve discussed with aerosols However, because some eruptions are incredibly explosive, the aerosols can be projected into the
above the clouds - where they will not rain out -so they can stay up there for a couple of years
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Much- Scream
Kratatoa
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Other cards in this set

Card 2

Front

No water, no life. Water is provided by the

Back

ocean and atmosphere.

Card 3

Front

No movement of air or water, no dispersal of simple organisms, or

Back

Preview of the front of card 3

Card 4

Front

And of course the atmosphere and ocean play many important roles in the Earth System irrespective of their interaction with the other components. E.g.

Back

Preview of the front of card 4

Card 5

Front

It is clear from looking at the different temperatures of planets in our solar system that greenhouse effects operate – on a massive scale Clearly the differences in temperature of Mercury Venus and Earth

Back

Preview of the front of card 5
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