MOTR wrote on Oct 22
nd, 2012 at 6:22am:
I'm not sure why you are making Rabbitoh out to be a dill when it's what they teach at Colombia University.
The Climate System
EESC 2100 Spring 2007
Text by Yochanan Kushnir, 2000.
Quote:Effective temperature.
By absorbing the incoming solar radiation, the Earth warms up, like a black body (see radiative heat transfer) and its temperature rises. If the Earth would have had no atmosphere or ocean, as is the case for example on the moon, it would get very warm on the sunlit face of the planet and much colder than we experience presently, on the dark side (the little warmth on the dark side would come from the limited amount of heat stored in the ground from the previous daytime - this is, to some extent, what we experience in a cloud-free, land locked desert climate).
All heated objects must emit electromagnetic radiation, particularly so if they are surrounded by empty space. This radiation is referred to as outgoing. As long as the incoming radiative flux is larger than the outgoing, the radiated object will continue to warm, and its temperature will continue to increase. This in turn will result in an increase in the outgoing radiation (according to the Stefan-Boltzman law the outgoing radiation increases faster than the temperature). At some point the object will emit as much radiation as the amount incoming and a radiative equilibrium (or balance) will be reached. Using what we have learned about radiative heat transfer and some geometric calculation we can calculate the equilibrium temperature of an object if we know the amount of incoming energy. Here is how we do that in the case of a planet rotating around the Sun:
First let us denote the solar radiative flux at the top of the planets atmosphere by So (for solar constant) and the albedo of the planet by a. Then let us figure out the total amount of radiation absorbed by the planet. To overcome the difficulty posed by the fact that the planets are spherical and their surface tilts with respect to the incoming radiation, note that the amount distributed over the sphere is equal the amount that would be collected on the planets surface if it was a disk (with the same radius as the sphere), placed perpendicular to the sunlight. If the planet's radius is R the area of that disk is πR2. Thus:
heat absorbed by planet = (1 - a) πR2So
The total heat radiated from the planet is equal to the energy flux implied by its temperature, Te(from the Stefan-Boltzman law) times the entire surface of the planet or:
heat radiated from planet = (4πR2) σT4
In radiative balance we thus have:
(4πR2 ) σTe4 = (1 - a) πR2So
Solving this equation for temperature we obtain:
Te = [(1-Aa)So / 4σ] 1/4
We have added a subscript e to the temperature to emphasize that this would be the temperature at the surface of the planet if it had no atmosphere. It is referred to as the effective temperature of the planet. According to this calculation, the effective temperature of Earth is about 255 K (or -18 °C). With this temperature the Earth radiation will be centered on a wavelength of about 11 μm, well within the range of infrared (IR) radiation.
Because of the spectral properties of the Sun and Earth radiation we tend to refer to them as "shortwave" and "longwave" radiation, respectively.
Speaking of the 33 degrees. There is a discussion going on that no-one seems to want to have. I dont know enough about it to comment on it, but you may be interested. May not.
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Contrary to popular myth this “33 degrees” is not observed, empirical fact at all. The book’s authors and converts to our science say it is the product of a botched equation by NASA’s Dr. James E. Hansen from the 1980′s. Currently, my article on this is doing the rounds.
Dr. Pierre Latour earlier this year proved that Hansen’s “33 degrees” is the result of a fatal mixing of a scalar temperature value with a vector temperature value (
not permitted in either math or physics). That no one questioned this till we ‘Slayers’ did suggests it is perhaps among the most successful elements of the GHE fraud. Pointedly, it duped two top skeptic climatologists, Dick Lindzen and Roy Spencer, among other leading skeptics, who never questioned its validity and when challenged opted to play “follow my leader.”
It appears Lindzen first swallowed the bogus “33 degrees” number at least since March 1990, as proven by his paper ‘Some Coolness Concerning Global Warming’ AMS, Vol 71. In September 2010 on his blog Spencer admitted he merely followed Lindzen’s lead. But Spencer went further and actually asserted (crassly) that Hansen’s “33 degrees” number offers a “real-world observed radiative-convective equilibrium.”
But both Spencer and Lindzen are shown, since March 2012, to have circled the wagons obstinately avoiding the issue. Despite our urging neither will apply due diligence to verify the providence of the number. But if they had looked more closely at the “33 degrees” from the outset they would have seen that the first value Hansen used to obtain it is a 3-D measure (a vector) of the infrared radiation emitted by Earth back into outer space (255K). Hansen then put that alongside a 2-D measure (288K), which is an average of surface weather stations (a scalar). That’s how Hansen and government climate science “got” it’s 33 degrees greenhouse gas effect. But anyone trained in higher math or physics knows this is not a permissible procedure as it’s the equivalent of adding apples to oranges
more
http://johnosullivan.wordpress.com/2012/10/21/now-australians-take-up-challenge-...