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Simple Chemistry and the Real Greenhouse Effect.
Blogging Tories ^ | March 2010 | Bill MacLean

Posted on 02/10/2011 9:29:16 AM PST by BillM

Simple Chemistry and the Real Greenhouse Effect.

Truths:

1. Most of the Sun’s radiation that gets to the Earth’s lower atmosphere passes through substantially unabsorbed.

2. Most of the radiation is then absorbed on contact with the Earth’s surface. This includes the majority water and the minority land.

3. Most of the Earth’s surface is either water or moist vegetation.

Most of the radiation from the sun is converted to infrared wavelengths at or near the surface.

The water molecules absorb the infrared radiation causing increased vibration within the individual water molecules. This is converted into translational energy during intermolecular collisions.

Water is an unusual compound. Its molecular weight (18) is half that of nitrogen (28) and less than half oxygen (32). Water should by all rights be a gas.

The reason water is liquid or ice normally, is that water molecules are naturally attracted to each other and form large aggregates which are substantially heavier than air.

When liquid water absorbs infrared radiation or is otherwise stimulated it vibrates more quickly and more intensely. This breaks down that tendency to aggregate.

In fact, in order for an associated water molecule to break free and escape into the air, a specific amount of energy must be absorbed. This is called the Latent Heat of Vaporization.

In fact, this is a very large amount of energy as anyone who has boiled water knows.

It takes 1 calorie of heat to raise the temperature of liquid water by 1 Celsius degree.

It take 539 calories to change one gram of water to steam.

Phase changes

Transitions between solid, liquid, and gaseous phases typically involve large amounts of energy compared to the specific heat. If heat were added at a constant rate to a mass of ice to take it through its phase changes to liquid water and then to steam, the energies required to accomplish the phase changes (called the latent heat of fusion and latent heat of vaporization ) would lead to plateaus in the temperature vs time graph. The graph below presumes that the pressure is one standard atmosphere.

A more complete explanation of the above

All of the energy (539 cal/gm) must be lost by exchange or radiation in order for the steam to condense.

This is THE ESSENSE of the GREENHOUSE EFFECT.

Enormous amounts of energy (principally translational and vibrational) are carried from the surface into the atmosphere by fast moving free or loosely associated water molecules.

Collisions between water molecules and the majority nitrogen and oxygen molecules transfer the energy to the greater atmosphere. As the energy level of the water molecules diminishes, the probability that water molecules will reaggregate increases. This leads to condensation and has the effect of transferring that 539 calories per gram to the rest of the atmosphere.

Now for the Kicker!

Carbon dioxide does NOT form aggregates. It is not lighter than air and thus does not rise quickly. There is no phase change when carbon dioxide enters the atmosphere. Carbon dioxide carries less than half the heat per molecule compared to water.

One gram of Carbon Dioxide heated at the surface by incident sunlight carries (2 * 539 = 1078) 1078 times less energy into the atmosphere than one gram of water.

Carbon dioxide represents 0.0387 % of the atmosphere. Water in the lower atmosphere represents 1% to 4% or 25 to 100 times the amount of carbon dioxide.

Combining the two statements above, Water is (25 * 1078 = 27,175) to (100 * 1078 = 108,700) times more responsible for greenhouse effect than carbon dioxide.


TOPICS: Education; Reference; Science; Weather
KEYWORDS: carbondioxide; globalwarming; globalwarminghoax; greenhousegases; greennewdeal; methane
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Beam me to Planet Gore !

21 posted on 02/10/2011 4:37:23 PM PST by steelyourfaith (ObamaCare Death Panels: a Final Solution to the looming Social Security crisis ?)
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To: ETL
The mechanism is that the earth warms from solar changes, then after many 100's to 1000 years or so, CO2 comes out of the deep ocean and that causes more warming and there is a slow feedback loop. The ice age atmosphere is generally very dry and CO2 has a greater proportional effect and it is going from 200 to 280 and is logarithmic.

Finally with the CO2 at around 260-280, and the atmosphere warmed and wetter, the feedback loop stops. That's why the interglacial periods stop around the current temperature or a little higher. The current addition of 100 more ppm has little effect for two reasons: the log scale means less warming for each additional amount of CO2. More importantly, weather starts to limit warming (see Eschenbach and Lindzen on thermostat-like mechanisms). The water cycle is a powerful global cooling mechanism and should operate a bit faster with a bit of CO2 warming. But mostly the water cycle responds to solar effects including geomagnetic effects that manifest in weather changes (e.g. more low clouds from more galactic cosmic rays or less from less).

I try to stay away from CO2 did this or that in ancient history (e.g. when it was much higher) because the earth was very different then. Many more volcanoes (the source of the CO2) affecting the climate, the sun was cooler, the continents were laid out differently. There are no clear relationships when you look very far back.

It is definitely a fact that we are in an extended ice age with scarce CO2. Now our extra CO2 may or may not help to keep us from falling out of the current interglacial back into the ice age. In the other direction, the chance of "catastrophic" warming from the extra CO2 is zero. Not even a tiny chance, it simply will not happen in our current geological configuration.

22 posted on 02/10/2011 5:38:43 PM PST by palmer (Cooperating with Obama = helping him extend the depression and implement socialism.)
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To: ETL

“This new data set shows that as surface temperature increases, so does atmospheric humidity,” Dessler said. “Dumping greenhouse gases into the atmosphere makes the atmosphere more humid. And since water vapor is itself a greenhouse gas, the increase in humidity amplifies the warming from carbon dioxide.”

I couldn’t find the original paper on which this statement is based. It only referenced a secondary article published in a journal by a writer who added his own unsubstantiated assertions to the original article. Be that as it may, it glosses over a very important reality. Increasing surface temperatures may or may not increase atmospheric humidity depending upon the presence or absence of water in that surface. It is axiomatic that heat can only evaporate water into water vapor if there is water present in the first place. For example, Death Valley, California is very arid even though it is very hot because very little rain falls there; therefore there is very little water in the soil in Death Valley to evaporate (create humidity) when the surface is heated.

Conversely, Huntsville, Alabama gets lots of rain and the surface if very wet. It, therefore, unlike Death Valley gets very humid when the ground is heated. Both of these locations lie roughly along the same parallel so they both receive roughly the same amount of sunlight every day throughout the year, yet the relative humidity in Death Valley is only about 24% on average and the relative humidity in Huntsville is over 70%.

I obtained the above numbers from the National Weather Service. Empirically measured Huntsville has nearly three times the amount of water vapor in the air than does Death Valley. So, if water vapor traps heat in the air and creates a positive heating feedback loop one would expect Huntsville to be much warmer on average than Death Valley, but its not; its cooler.

Huntsville, the city with nearly three times the amount of the “greenhouse gas” water vapor in the air, is about 7 °C cooler than Death Valley! It is only 17 °C on average while Death Valley, the city with about one third the amount of the “greenhouse gas” water vapor in the air, is about 24 °C on average. Again, they both lie along the same parallel so they both receive roughly the same amount of sunlight every day all year long.

Therefore, we observe that the city with nearly three times the amount of water vapor in the air is not only cooler than the city with one third the amount of water vapor in the air, it is significantly cooler. The water vapor in Huntsville, contrary to the “greenhouse effect” hypothesis in reality has a marked cooling effect, not a warming effect, on the climate in and around Huntsville. This is an “anti-greenhouse” effect.

The more water vapor there is in the air the cooler the air is (according to the figures that I obtained from the National Weather Service.) This is a negative feedback and explains why the earth, which is covered with 70% oceans, has not already experienced runaway “water vapor feedback.” As the surface temperature increases by whatever means, if there is water in the ground to evaporate, that extra heat will create more humidity; this, in turn, cools the surface, which inhibits further evaportion. This reality is reflected in the temperature record which shows Huntsville to be about 7 °C cooler on average than Death Valley even though they both receive the same amount of sunlight.

Should one assert that this cooling is due to the greater cloud cover in Huntsville that would simply affirm the powerful negative feedback that clouds provide as they mitigate surface warming through shade and rain.


23 posted on 01/24/2012 6:40:45 AM PST by allen_carl (Water Vapor and clouds cool the atmosphere)
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