Week 3
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If you are looking at a wiggly line what is the wavelengths?
the difference in distance between the peaks
What is an example of a long and a short wavelength?
Long - radio/microwave - size of a building-butterfly Short- Gamma ray or x-ray - size of atmoic nuclei-atoms
What is the colour relationship for long and short wavelengths?
Only a small visible range
What is the relationship between temperature and wavelength
cooler objects emit longer wavelenths, hotter objects emit shorter wavelengths
What kind of radiation can penetrate the earths atmosphere and what is in the grey and what can;t
CAN Radio and infrared-visible MAYBE Some radio and some infrared CANNOT microwave and vible-gamaray short wave
What is Planck’s law
Hotter objects emit more radiation - higher specific spectral emittance hotter objects emit short wave radiation and more radiation overall the peak wavelength at which objects emit decreases with increasing temperature
What does the sun emit?
the peak is in the visible part of the spectrum
What kind of wavelength does the earth emit
the earth is colder the sun, emits in the infrared part of the spectrum
what percentage of the suns energy does the earth absorb and reflect?
70% absored 30% relected- espeically by light surfaces like clouds, snow and deserts
What is the unit of mesurement for radiative fluxes
W/m^2 the flow of energy through a given surface area over a certain amount of time
What is the global-mean incoming solar radiation and what is the net-absorbed solar radiation
global-mean incoming solar radaition = 340W/M^2 net-absorbed solar radiation is 240w/m^2
What is a radiative balance and how is it achieved?
energy in= energy out emissions of infrared radiation to space
Without the atmosphere what temperature would the earth be?
-19oc
Without the ghg effect whast would the earth temperature be?
15oc
What is the Co2 content of the atmosphere for Earth and Venus?
.02% = earth 96% Venus
What is the ghg effect?
radiation emitted by earth is trapped by gases in the atmosphere and re-emitted in all directions when it is re-emitted down this is the greenhouse effect the large up and down longwave fluxes idea that there is an asymmetry between absorption by ghg of infrared and visible radiation- traps infra-red
What is albedo?
the reflection of solar energy depends on the albedo the earth atmosphere high albedo - light reflective surfaces like snow and clouds low albedo - dark surfaces like water and forests
How do you calculate albedo?
albedo= reflected solar radiation/incoming solar radiation 1= everything is reflected 0= nothing is reflected
What is the earths mean albedo
30% however this varies spatially and depends on the surface type
Where is shortwave radiation absorbed
mainly at the surface - some in the atmosphere but this is more UV rather than visible Ozone layer - absorbs harmful carcogenic UV - holes in the ozone due to man-made CFCs
Why are there different amounts of emission from different parts of the atmosphere
due to temperature changes - but what matters is the emissions out to space typical level that escapes to space has a temperature that corresponds to that emission
What is water vapour opque to?
infrared radiation at many wavelengths - therefore it absorbs it
Why is there so much focus on carbon dioxide
it stays for longer in the atmosphere and thermodynamically unreative - very stable molecule once produced it will remain for a long time
Methane from? and how much in the atmosphere?
gas leaks and livestock has more than doubled