Water Vapor Can “Trap” Heat — CO2 Cannot

Those who talk about carbon dioxide affecting temperature ignore the fact that water’s potential to affect air temperature is well established in science. Water vapor is the only atmospheric gas that can hold or “trap” heat.

Those who spend much time in greenhouses know that they are often very humid places because water evaporates from plants and from surfaces that get wet when the plants are watered. Meteorologists typically refer to the water vapor content of the air as relative humidity which is how close the air is to holding as much water vapor as it can hold at its current temperature.

Unfortunately many climatologists waste so much time on the nonexistent impact of radiation on air temperature that they don’t provide sufficient emphasis to the significant impact of water vapor on air temperature. Those who want to blame climate changes on humans ignore the fact that the combustion of hydrogen containing fossil fuels increases the amount of water vapor in the air. Other human actitivies such as watering yards, washing cars and operating public fountains also add water to the atmosphere.

Water has some special thermal characteristics that can significantly affect atmospheric temperatures. Water heats and cools significantly slower than other components of the atmosphere. Water vapor needs to absorb over four times more heat energy than the same mass of other air molecules to raise its temperature the same amount. When it cools it releases four times more heat than other gases.

Thus as the water vapor content of the air increases the atmosphere will heat and cool slower than when the air is drier. This process tends to keep the temperature from rising as high during the day or cooling as much at night, although the increase in the overnight low may lead to an increase in the daytime temperature because the air doesn’t have to heat as much to reach a higher temperature. In equatorial areas deserts have higher maximum temperatures and lower minimum temperatures than jungle areas where the humidity is higher.

Water vapor possesses what physicists have traditionally called “latent” heat. Latent heat refers to the heat energy water molecules must absorb to go from a solid to a liquid (heat of fusion 80 calories/gram) or a liquid to a gas(heat of vaporization 540 calories/gram). This energy isn’t reflected in the temperature of the water vapor. However, when water vapor condenses back to a liquid, or freezes, the release of this latent heat can raise the temperature of the air. A gram of water vapor releases enough heat energy when it condenses to raise the temperature of 2 kg of air by 1 C.

At a dew point of approximately 65 F water vapor in the atmosphere holds as much heat energy as the rest of the atmosphere.   This condition explains why dew points above 65 F are associated with the strongest thunderstorms.

Physicists define a “calorie” as the amount of heat required to raise the temperature of a gram of water 1 C. 27 C (82 F) is the same temperature as 300 Kelvin [the absolute temperature scale]. At 300 K water vapor has 300 calories of heat from its temperature and 620 calories of latent heat.

The dew point is the temperature at which water vapor will condense on objects or aerosals. The dew point normally is the lowest temperature the air will fall to. As the water vapor content of the air increases the dew point rises and the air doesn’t get as cool at night.

The situation is more complex than I am presenting it in this post. I . The important facts to consider are that increases in humidity can raise the low, or minimum temperature, and limit the high, or maximum temperature, each day.  In areas where significant snowfall  occurs,  the increase in low  temperature can increase the melting of snow and ice by keeping the temperature  above freezing for longer periods of time.

I recently came across a 10 year old study done by David R. Easterling of the National Oceanic and Atmospheric Administration’s National Climatic Data Center in Asheville, N.C., indicating that humidity had increased and, as should have been expected, the minimum temperature had been increasing and the difference between the minimum and maximum daily temperatures, diurnal temperature range (DTR), had been declining.

The potential impact of changes in atmospheric water vapor are real science. Water vapor holds a substantial amount of heat energy. The only potential impact climatologists can find for carbon dioxide is the highly questionable claim about absorbing and re-radiating low energy IR. But then, if would be difficult for the politicians behind the global warming scare to make a case for getting rid of water.

Global Average Temperature Debate – Much Ado About Nothing

The global warming priests have presented no evidence that the process they claim causes “global warming” exists.   They just illogically claim that any increase in what they call the “global average temperature”  can only result from carbon dioxide in the atmosphere.

Paul  Homewood has recently reported on questionable manipulation of temperature data used to calculate this global average temperature.   Anthony Watts has documented problems with temperature data for several years on his blog.

The controversy over the accuracy of the data can be viewed as much ado about nothing because the so-called global average temperature  “is thermodynamically as well as mathematically an impossibility, says Bjarne Andresen, a professor at The Niels Bohr Institute, University of Copenhagen, who has analyzed this topic in collaboration with professors Christopher Essex from University of Western Ontario and Ross McKitrick from University of Guelph, Canada.”

“It is impossible to talk about a single temperature for something as complicated as the climate of Earth”, Bjarne Andresen says,  an expert of thermodynamics. “A temperature can be defined only for a homogeneous system. Furthermore, the climate is not governed by a single temperature. Rather, differences of temperatures drive the processes and create the storms, sea currents, thunder, etc. which make up the climate”.

“While it is possible to treat temperature statistically locally, it is meaningless to talk about a a global temperature for Earth. The Globe consists of a huge number of components which one cannot just add up and average.”

Even if the concept of a global average temperature was meaningful, the method of determining it is too primitive to produce a valid average.  Instead of using hourly temperatures, they just use the high and low temperature which may not be representative of temperatures during the day.   For example, the arrival of a strong  cold front late in the day can make the low temperature significantly lower than temperatures during the rest of the day.

Even social scientists have moved away from using broad averages because such averages cover up too much information.   For example, social scientists look at the number of people in various age groups instead of the average age.   The number of homes with children or with one adult or two adults is used rather than the average household size which always ends up with a fraction of a person.   In the last presidential election people talked about the 3% in one income group and the percentage that didn’t pay any income tax instead of the per capita income.

A third problem with the climate shaman’s obsession with temperatures is that although a temperature decrease would disprove the claim of global warming, a temperature increase would not prove that CO2 was responsible.   The global warming preachers routinely commit the logical fallacy   “post hoc ergo proper hoc.    I learned that phrase in high school English class. The global warming fanatics either didn’t learn about the fallacy or don’t understand that the fact that A follows B doesn’t necessarily mean A causes B.

With their simple minded view of the situation they blithely assume that any temperature increase could only be a result of an increase in CO2.   They seemingly cannot understand that they must provide evidence that an increase in CO2 would cause any temperature increase.  They ignore the fact that other factors are known to be able to increase air temperature.

The teracalories of heat human activity generates each day would be the most likely cause of any temperature increase that wasn’t caused by an increase in the sun’s output.    Each teracalorie is capable of  raising the temperature of a trillion grams of water by 1 Celsius.   A teracalorie would raise the temperature of about 4-5 trillion grams of air 1 C.

Except in desert and tropical areas, most of the time the human body has a higher temperature than the air.   Automobile engines and other human technology generate sufficient heat to boil water.   Many types of air conditioning systems remove heat from the interior of buildings and transfer it outside where it heats the outside air.   Some of the heat used to warm the interiors of buildings in cold weather leaks out and heats the outside air.


I have published numerous posts on the controversy over alleged global warming over the last few years. I plan to consolidate them here with some new posts so they are easier to find.

There is no scientific basis for the claim that carbon dioxide in the atmosphere can control air temperature. The belief that greenhouses and the atmosphere trap radiation to raise temperature was disproved a century ago by R.W. Wood.

Unfortunately some religious fanatics masquerading as scientists continue to push the belief that humans, rather than factors beyond human control, determine earth’s climate. Their attempts to silence anyone who opposes their belief is the biggest threat to empirical science since the attacks on Copernicus and Galileo.