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Planetary cloud albedo level is a function of solar energy absorption
Pioneer photo of Venus in the UV
OK, I think we have more clarity on the difference between N&Z and Harry Dale Huffman’s interpretation of Venus and Earth data.
> On 1/29/2012 12:34 PM, Rog Tallbloke wrote:
>
> Hi Ned,
>
> I think I’ve managed to get Harry Dale Huffman to state what the key
> point he has at issue is:
>
> “I deduced nothing about the “proportion” or “amount” of solar energy
> absorbed by the atmosphere. I deduced something about the fraction of
> solar energy absorbed by the atmospheres of both Venus and Earth: They
> absorb the same fraction, and it is in the infrared. The amount they
> absorb is different, as the definitive fact is, Venus absorbs 1.91
> times as much solar power as the earth (so its atmospheric temperature
> is 1.176 times that in Earth’s atmosphere, at a given tropospheric
> pressure), because it is closer to the Sun (and not for any other
> reason).
>
> I am waiting to see that fact acknowledged as such by all, in all
> the debates.”
>
> Harry Dale Huffman
>
> Is this something you would agree with him on? If so, we can tell him
> that, and move forward together.
>
> Thanks for your time.
>
> Rog
Galileo photo of Earth in the UV
On Sun, 29 Jan 2012 15:13:55 -0700, Ned Nikolov wrote:
> Rog,
>
> I agree with Huffman’s general finding that the temperature of
> Venus’s atmosphere should be about 1.176 times that of Earth’s
> atmosphere at the _same_ pressure level. This is fully consistent with
> our theory! Indeed, the solar irradiance at the top of Venus’
> atmosphere is about 1.92 time larger than the solar irradiance above
> Earth’s atmosphere. Since temperature is proportional to the 4th root
> of radiation, it follows that 1.92^0.25 = 1.177, which is very close
> to the ratio reported by Hoffman
>
> However, Huffman needs to correct his terminology. The ratio 1.91
> (or 1.92 in my calculation) is NOT how much more radiation Venus
> _absorbs_ than Earth, but how much _larger_ the SOLAR IRRADIANCE (i.e.
> solar constant) of Venus is compared to that of Earth. This is the
> solar flux ON TOP OF THE ATMOSPHERE (TOA) and BEFORE correcting for
> the albedo. The actual_ absorbed_ radiation by a planet is calculated
> by the formula: S*(1-A)/4, where S is the TOA solar irradiance, and
> A is the albedo. Since A = 0.75 for Venus while A = 0.30 for Earth ,
> Venus actually absorbs some 31% LESS radiation than Earth despite
> being closer to the Sun and having a larger solar irradiance!
> Huffman states “…_Venus absorbs 1.91 times as much solar power as
> the earth_ ..”, which is INCORRECT! Venus is ILLUMINATED 1.91 times
> stronger than the Earth, but it absorbs 31% less [incident] radiation than Earth.
>
> There is a very interesting phenomenon here, which is that surface
> temperature apparently scales with TOA irradiance rather than with
> actual_ absorbed_ radiation. We discuss this in our full paper. The
> implication of this is that the atmospheric albedo (cloud cover
> reflectivity) is a function of the internal energy of the system
> maintained by solar heating and pressure. In other words, the cloud
> albedo is mostly a _byproduct_ of the atmospheric energy, not an
> independent driver of planetary climate as assumed by the current GH
> theory.
>
> – Ned
>
Exciting stuff!!
Harry’s says this in his original article:
“This result also flies in the face of those who would say the clouds of Venus reflect much of the incident solar energy, and that therefore it cannot get 1.91 times the power per unit area received by the Earth — the direct evidence presented here is that its atmosphere does, in fact, get that amount of power, remarkably closely. This in fact indicates that the Venusian atmosphere is heated mainly by incident infrared radiation from the Sun, which is not reflected but absorbed by Venus’s clouds, rather than by warming first of the planetary surface. (It also indicates that the Earth atmosphere is substantially warmed the same way, during daylight hours, by direct solar infrared irradiation, and that the temperature profile, or lapse rate, for any planetary atmosphere is relatively oblivious to how the atmosphere is heated, whether from above or below.)”
However, the Albedo of Venus is what it is, and can be measured quite accurately from it’s brightness. Harry told me that:
“I deduced something about the fraction of solar energy absorbed by the atmospheres of both Venus and Earth: They absorb the same fraction, and it is in the infrared.”
I pointed out that convection currents are set up in shallow lakes on Earth, from the heat absorbed in the dark coloured bottom. Clearly, Earth does not absorb anything like as much of the incident solar radiation in the atmosphere as Venus does, since almost none of it reaches Venus’ surface. There seems to be some contradiction in what Harry says, but I’ll let everyone help tease it out in comments.
Read more at Tallbloke Talkshop
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