EXXON Contradicts its Own Scientists

[_Res Ipsa]

The problem with religious nutjobs like Brad is they really don't know what they are talking about.

I mentioned already that CH4 is combustible. What the means is it naturally breaks down either through direct combustion or because of radiation. So all the CH4 in the atmosphere right now will be gone in 10 years unless it is replaced. Also, even though CH4 is 20 times more powerful of a greenhouse gas than CO2, there is a slight problem religious zealots like Brad fail to mention. It's a narrow band absorber which overlaps with another greenhouse gas H2O. And since there is vastly more H2O in the atmosphere that already absorbs the same spectrum as CH4, there really isn't any contribution made by CH4 to global warming.

So, see what Tobin has done here? He's identified two factors other than the amount of a greenhouse gas in the atmosphere that affect a greenhouse gas's ability to warm the atmosphere: the absorption spectrum of the molecules in the gas and the distribution of the gas in the atmosphere. So, he has known all along that there are other things besides the quantity of gas in the atmosphere that determine whether a greenhouse gas is significant in terms of the ability to warm the atmosphere. So, when I repeatedly asked him the question whether he was claiming that the quantity was the sole determining factor, he knew the answer was "no." Why wouldn't he just say that?

Now, he has introduced a new argument: methane can't absorb and re-radiate long-wave radiation because water vapor has the same absorption spectrum and so is already absorbing all the radiation at the relevant wavelengths. As we haven't finished with evaluating Tobin's claim that water vapor is 4% of the atmosphere, I'm going to table that issue and come back to it. As we will see, Tobin's theory was disproved in the 1950s, so he's over half a century behind in the science. But let's not let him distract us by throwing in new crap on top of his old crap.

[_Res Ipsa]

Earth to the religious lunatics in this thread, namely Brad. I know science isn't your thing because your assumptions are divorced from reality. I want you to think about something very carefully though. The vast majority of the world is covered by something? Your assumptions about humidity fails to take into account the actual geography of the planet Earth and something special that happens in those areas. Given that fact, 4% is actually a very good number. But again, you have to have an IQ higher than 60 to figure out why.

Tobin here is, of course, referring to supersaturation. Under certain conditions, the atmosphere can hold more than 100% humidity. But note what Tobin doesn't do: he doesn't provide any data about (1) where supersaturation occurs; (2) what percentage of the atmosphere is actually supersaturated at any given time; or (3) what the relative humidity typically is in supersaturated air. Remember Tobin's claim: he wants you to believe that the percentage of water vapor in the atmosphere is 4% when basic physics tells us:

1. It requires a temperature of 85F or so to even permit the atmosphere to even hold that much water vapor; and
2. At that temperature, it would require 100% relativity to reach that figure. (lower if you get hotter)

If he wants to "rescue" his 4% number by invoking supersaturation, he's going to need to provide evidence. So let's place our bets. Will we hear evidence? Or just more bluster?

[_Tobin]

Actually when the atmosphere is supersaturated with humidity, the atmosphere can hold up to 10% H2O. The ceiling isn't 4%. And given that 72% of the world is covered with oceans, it is more likely than not that the air above that water is saturated by 4% or more with H2O.

[_The CCC]

Actually when the atmosphere is supersaturated with humidity, the atmosphere can hold up to 10% H2O. The ceiling isn't 4%. And given that 72% of the world is covered with oceans, it is more likely than not that the air above that water is saturated by 4% or more with H2O.

Relative humidity is dependent on temperature. It falls out as rain/snow when it can no longer hold more water.

[_Res Ipsa]

Actually when the atmosphere is supersaturated with humidity, the atmosphere can hold up to 10% H2O. The ceiling isn't 4%. And given that 72% of the world is covered with oceans, it is more likely than not that the air above that water is saturated by 4% or more with H2O.

Another good example of Tobinism: "the atmosphere can hold up to 10% H2O." Yet, no explanation of the conditions under which that can occur. Then just a flat out claim that the water above the oceans is supersaturated to some unexplained extent so that it is more likely than not 4%.

This is not evidence. This is Tobin hand waving.

But, there really is a straightforward way to resolve this: compare the mass of water vapor in the atmosphere v. the mass of CO2. That will give us an apples to apples comparison of how much of each there is. The percentages look something like this:

Water vapor: .3%
CO2: .06%

That's right. There is only 5X as much water vapor in the atmosphere than there is CO2; not the absurd 100X Tobin claims. Here's one source. http://www.realclimate.org/index.php?p=142 (Hint -- Tobin won't consider it because the source is actual climate scientists) But look at any credible source you want. The numbers aren't controversial.

Why is Tobin so far off? Because his 4% number is absurd. He's taking a percentage that applies to fully saturated air at 85F or so and then applying it to the whole atmosphere. He neglects that the average surface temperature is much lower. He neglects that humidity is not 100% everywhere across the earth. He neglects that as you rise up through the troposphere, temperature falls off rapidly. He neglects that, as you go up through the atmosphere, the percentage of water vapor quickly goes to practically zero. Based on no actual evidence, he simply claims that supersaturation actually makes up for all of that.

Tobin's 4% number is simply made up BS. There is about 5X as much water vapor in the atmosphere as there is CO2. But quantity of the gas is not the whole story, as Tobin has already admitted. The radiation absorption of each greenhouse gas molecule is different and must be taken into account. The distribution of gas in the atmosphere must be taken into account. And, the residency of the gas in the atmosphere must be taken into account. Tobin's argument is flat-ass wrong because he looks at only one of many factors in what determines how adding a greenhouse gas to the atmosphere will affect it's temperature and because he uses a vastly overstated figure for the percentage of water vapor in the atmosphere.

[_Res Ipsa]

Some general information on supersaturation:

As water evaporates from an area of the earth surface, the air over that area becomes moist. Moist air is lighter than the surrounding dry air, creating an unstable situation. When enough moist air has accumulated, all the moist air rises as a single packet, without mixing with the surrounding air. As more moist air forms along the surface, the process repeats, resulting in a series of discrete packets of moist air rising to form clouds.[5]

This process occurs when one or more of three possible lifting agents - cyclonic/frontal, convective, or orographic — causes air containing invisible water vapor to rise and cool to its dew point, the temperature at which the air becomes saturated. The main mechanism behind this process is adiabatic cooling.[6] Atmospheric pressure decreases with altitude, so the rising air expands in a process that expends energy and causes the air to cool, which reduces its capacity to hold water vapor. If the air is cooled to its dew point and becomes saturated, it normally sheds vapor it can no longer retain, which condenses into cloud.[7] Water vapor in saturated air is normally attracted to condensation nuclei such as dust and salt particles that are small enough to be held aloft by normal circulation of the air.The water droplets in a cloud have a normal radius of about 0.002 mm (0.00008 in). The droplets may collide to form larger droplets which remain aloft as long as the drag force of the air dominates over the gravitational force for small particles.[8]

For non-convective cloud, the altitude at which condensation begins to happen is called the lifted condensation level (LCL), which roughly determines the height of the cloud base. Free convective clouds generally form at the altitude of the convective condensation level (CCL). Water vapor in saturated air is normally attracted to condensation nuclei such as salt particles that are small enough to be held aloft by normal circulation of the air. If the condensation process occurs below the freezing level in the troposphere, the nuclei help transform the vapor into very small water droplets. Clouds that form just above the freezing level are composed mostly of supercooled liquid droplets, while those that condense out at higher altitudes where the air is much colder generally take the form of ice crystals. An absence of sufficient condensation particles at and above the condensation level causes the rising air to become supersaturated and the formation of cloud tends to be inhibited.[7]

...

The amount of water that can exist as vapor in a given volume increases with the temperature. When the amount of water vapor is in equilibrium above a flat surface of water the level of vapor pressure is called saturation and the relative humidity is 100%. At this equilibrium there are equal numbers of molecules evaporating from the water as there are condensing back into the water. If the relative humidity becomes greater than 100%, it is called supersaturated. Supersaturation occurs in the absence of condensation nuclei, for example the flat surface of water.

Since the saturation vapor pressure is proportional to temperature, cold air has a lower saturation point than warm air. The difference between these values is the basis for the formation of clouds. When saturated air cools, it can no longer contain the same amount of water vapor. If the conditions are right, the excess water will condense out of the air until the lower saturation point is reached. Another possibility is that the water stays in vapor form, even though it is beyond the saturation point, resulting in supersaturation.

Supersaturation of more than 1–2% relative to water is rarely seen in the atmosphere, since cloud condensation nuclei are usually present.[25] Much higher degrees of supersaturation are possible in clean air, and are the basis of the cloud chamber.

https://en.wikipedia.org/wiki/Cloud_physics [emphasis mine]

[_Tobin]

Supersaturation of more than 1–2% relative to water is rarely seen in the atmosphere, since cloud condensation nuclei are usually present.

That is meaningless gibberish as cited. But I'm sure it makes sense to Brad because he doesn't understand that clouds are made of water vapor. In his head, I'm sure they are made of something exotic like CO2.

[_Res Ipsa]

Supersaturation of more than 1–2% relative to water is rarely seen in the atmosphere, since cloud condensation nuclei are usually present.

That is meaningless gibberish as cited. But I'm sure it makes sense to Brad because he doesn't understand that clouds are made of water vapor. In his head, I'm sure they are made of something exotic like CO2.

Notice what Tobin still has not presented: any evidence to back up his claim about supersaturation.

Here's a textbook on the microphysics of clouds and fog. Link

Saturation does vary within clouds -- both slightly above and below 100%. It "rarely" gets above 102%. The mean within clouds is about .1% supersaturation.

Note that Tobin also neglects how air gets supersaturated in clouds. Warm, moist air rises. As it rises, it cools. As it cools, it's capacity to hold water vapor is decreased. (See the graph). So, yes, the relative humidity can rise a little above 100%. But that's only because the air is colder and can't hold as much water vapor. So, the concentration of water vapor in that air isn't anywhere near 4% because the temperature of that cooling air isn't anything close to 86F.

In other words, I've shown how using the physics of water vapor saturation, the actual percentage of water vapor in the entire atmosphere must be much lower than 4%. Tobin doesn't dispute that, but claims supersaturation puts so much water vapor into the air that it can make the entire atmosphere average out to 4%. That means these supersaturated areas must have water vapor percentages that are much, much higher than 4%. But they can't, because they are only supersaturated at all because they are cooling.

Tobin's math doesn't work, and his claims aren't backed up by the data. At all.

[_Tobin]

Actually, Brad already supplied the chart. But because he is bad at math, he can't figure out the saturation rate as you increase the temperature. This chart however isn't about supersaturation or the differences at varying pressures, which allows for even higher saturations than the 6% his chart tops out at.

[_Res Ipsa]

Evidence, Tobin. Show us some evidence or admit you don't know what you are talking about.