I have some time to devote to schooling SA in atmospheric physics today:
Steve_American wrote:. . . One point of a fact I need to point out at the start is --- the reasons that climate scientists do not talk much about the effect of water vapor in the air are 1] The amount of water vapor can not be effected directly because the oceans are a huge source of more or less water vapor depending on things like the temp of the oceans and air above them. Warm water evaporates faster and warm air holds more water vapor, which is why it sometimes rains more than before and causes flooding.
That is more or less correct. Water vapor is in an equilibrium we can't significantly affect, including by CO2 emissions, because the negative feedbacks are too strong.
And, 2] The amount of water vapor in the air depends on the amount of CO2 in the air,
No, that's just false. The amount of CO2 in the air (pre-industrial) depended on the temperature, and so did water vapor. CO2 itself cannot affect water vapor more than microscopically unless it is far lower than it has ever been.
which scientist believe heats the ocean & air, so scientists can calculate in their models the amount of water vapor by knowing the CO2 level.
That CO2 controls temperature is an inaccurate model assumption, not a fact.
He said his 40 wool blankets represent the effect of water vapor in the air because H2O is 40 times better at absorbing IR het/light than CO2 is.
No, because there are ~40x as many H2O molecules in the air near the earth's surface as CO2 molecules. The difference in IR absorption per molecule is like the difference between a wool blanket and a cotton one: water vapor absorbs IR better than CO2, just as wool is a better insulator than cotton.
. . . Just above TtP asserts that only absorption CO2 matters, all the rest can be ignored, so he does ignore it. However, in his reply to me on the last page he didn't ignore water vapor. He said it absorbs 40 times more than current levels of CO2 do.
I ignore water vapor in the previous case because its GH effect is effectively constant and cannot be significantly affected by human activity, including CO2 emissions. I include it in the present case because it explains why Angstrom got the results he did, and why anyone repeating his experiment will get the same results.
. . . There TtP wrote: "CO2's effect is strictly on IR absorption."
I think that TtP hopes that you will accept that absorption of IR heat/light means that the IR heat/light is blocked. It seems like it because [while he also asserts that energy in = energy out] here he wants you to believe that because the IR heat/light is absorbed it can not later somehow escape into space.
No, it is absorbed and re-emitted over and over again, maybe thousands of times, before it makes its way high enough in the atmosphere to escape into outer space.
Here he asserts that CO2's only effect is on absorption. If this was so, [so the CO2 does NOT reradiate the IR heat/light] then it follows that the CO2/air would be getting hugely hotter and would heat the air around it to millions of deg.C. This doesn't happen because the heat/light is (in fact) reradiated.
No, its effect on surface temperature is based on its absorption of IR radiation because that's the only way it can
have an effect. The IR is immediately re-emitted in a random direction. The notion that CO2 has a significant effect on the earth's surface temperature is based on the fact that the re-emitted IR can go back down to the earth's surface. But as Angstrom showed, adding CO2 to standard atmospheric air has so little effect on IR absorption that the amount re-emitted back down to the surface is also barely affected.
I'm sure that TtP knows this. So, why did he assert that only absorption matters?
See above. Only absorption matters because re-emission can only happen after absorption.
. . . Is it because some is reradiated up and some down? This makes the description of the process very complicated. Too complicated to say it in a paragraph that a lay reader will be able to understand.
Nevertheless, that is what happens, and that is the relevant process. The lay reader may indeed find this difficult to understand, hence my blanket analogy.
The short answer is that the amount of energy that escapes to space must be very, very close to amount of solar energy that comes into the lower atmosphere or reaches the surface. We know this because each day, month, or better averaged over a year, the Earth warms or cools only about 0.0001 deg.C/day. That is 0.0001 deg.C per day.
No, we know it because the whole process is regulated by powerful negative feedbacks: the hotter something is, the faster it cools; the more CO2 there is in the air at the emission altitude, the more IR-excited molecules there are to emit IR to outer space; and the higher the emission altitude, the wider the angle that encompasses the overhead circular escape window.
. . . When TtP says that the IR heat/light is all absorbed in the 1st many meters from the land or water surface he may be right. But, it is all reradiated, half up and half down. Now as I just said, almost all of it does somehow reach space after being absorbed and reradiated many times. It is not blocked in the lower atmosphere.
You are learning from my explanations. Good.
. . . Therefore, it doesn't matter if it is all absorbed near the surface.
Yes, it does, because the difference between almost all and very nearly all is very small.
Almost all of the energy eventually reaches space.
It all does. In fact, a little more than that does, because the earth is constantly losing heat generated by radioactive decay in its interior, the friction of the tides converting its rotational energy into heat, etc.
. . . This percentage is very tiny. So, tiny that every possible verbal argument will not be accurate enough to pick up the tiny change that adding more CO2 to the air causes. However, it adds up more and more as the days become decades. That is, if you add up 0.0001 deg.C /day over the 10,957.5 days in 3 decades it becomes 1.09575 deg.C over 3 decades. If the amount of heating per day is actually 0.0002 deg.C/day then over 3 decades that total amount of heating is 2.1915 deg.C, or about 1.461 deg.C over 2 decades.
No. The negative feedback takes over. If the earth gets even microscopically warmer, it immediately just radiates heat away faster.
BTW --- climate scientists' models have to include the increase in water vapor in the air that will cause more heating.
The increase in water vapor caused by CO2 is a small fraction of what is assumed in the models.
This increased water vapor is caused by more heating caused by more CO2 in the air. There is nothing we can do about the increased water vapor, except reduce CO2 emissions.
No, the assumption that CO2 will somehow cause a big positive water vapor feedback is not based on any credible physical principle, and is disproved by the known negative feedbacks. It has simply been assumed to make climate models more sensitive to CO2.