What keeps Earth warm – the greenhouse effect or something else?

Greenhouse-effectPlanet Earth is 33 degrees C warmer than a theoretical planet without an atmosphere would be. Climate alarmists attribute this warmth to the radiative effects of greenhouse gases in the atmosphere. But there is another, more basic mechanism which accounts for the surface temperature.

First, a reminder of what the greenhouse effect is: solar radiation penetrates the atmosphere and warms the surface of the earth. The earth’s surface radiates thermal energy (long-wave infrared radiation) back into space. Some of this radiation is absorbed and re-radiated back to the surface and into space by clouds, water vapor, methane, carbon dioxide, and other gases.

Scottish physicist James Clerk Maxwell proposed in his 1871 book “Theory of Heat” that the temperature of a planet depends only on gravity, mass of the atmosphere, and heat capacity of the atmosphere. Greenhouse gases have nothing to do with it. Many publications since, have expounded on Maxwell’s theory and have shown that it applies to all planets in the Solar System.

Most papers on this subject are written in calculus and difficult to follow. A more readable explanation is given by a post at the HockeySchtick here. Another readable explanation is given by Hans Jelbring in his 2003 paper “The ‘Greenhouse Effect’ as a Function of Atmospheric Mass.”

Putting aside all the theoretical and dense reading required by the thermodynamic explanations, it occurs to me that we may have a practical demonstration of this alternate mechanism right here in Arizona.

Consider the Grand Canyon. The river level is 4,900 feet below the South Rim and 5,900 feet below the North Rim. Does the extra weight of the atmosphere at the bottom of the Canyon make the bottom warmer than the rim? Even though cold air sinks, the bottom of the Canyon is always warmer than the rim, at any time of the year, as shown by temperature measurements in the table below. Notice also that the higher North Rim is almost always cooler than the South Rim. This is a demonstration of the “lapse rate.” Atmospheric pressure decreases with altitude. This is because as you go higher up there is less air above you, and therefore less downward force due to the weight of this air. As pressure decreases, air expands and cools.

And just to make things interesting, a 2013 paper in Nature Geoscience explains why “A minimum atmospheric temperature, or tropopause, [separating stratosphere from troposphere] occurs at a pressure of around 0.1 bar in the atmospheres of Earth, Titan, Jupiter, Saturn, Uranus, and Neptune, despite great differences in atmospheric composition, gravity, internal heat and sunlight.” This shows that temperature is controlled by pressure, not greenhouse gases.

By the way, in the troposphere, heat transfer is mainly by convection, i.e., weather, whereas in the stratosphere heat transfer is mainly by conduction/radiation.

Grand-Canyon-temps

See also:

Satellite data show that CO2 has almost no effect on global warming

5 Comments

  1. seems simple enough – temperature is directly proportional to pressure – anyone filling or emptying a compressed gas cylinder will see this – so is the Grand Canyon a vessel that holds pressure thus warming itself as ‘atmospheric down pressure occurs’ – in a specific localized manner – ok I buy it… but is a ditch warmer than the surface – say an arroyo ? I think the colder air does sink into the low lands – does this sinking in itself create more pressure – I do and we see it as ‘fog’ when other atmospheric conditions are appropriate – is the bottom of the canyon warmer than the top… yup lots! Does gravity make a difference – why wouldn’t it I think more the question than does it. I’ve always joked I came back to Tucson because we have better gravity – now knowing that gravity does vary from point to point on the planet – it gives me new meaning to the saying ‘home sweet home’ and maybe it is all about the gravity – why we feel more comfortable at home… and perhaps in places with similar gravity – atmospheric pressure grades.

  2. I guess lots of this is lost on the “scientists” bowing to the human-caused global warming gods. This is real science, not the mumbo-jumbo the greens come up with to justify their feeble causes.

  3. When have facts ever gotten in the way of “Climate Scientists”? When the word scientist or science has to follow a name such as global warming….it’s a tell (like in poker) that it’s not legitimate. It’s kind of fun to follow the phonies and the grant money. Without money there would be no such thing.

  4. ‘with out money there would be no such thing’ – so money and scientific out come or reality are directly proportional to the proposed outcome and the taxes collected are a square root of that ‘new reality’ – now that is some science – sounds like they’ve invented the perpetual money machine.

  5. 110 low record temperatures were broken this past week …and the headlines read…”warmest fall in years.”

    It has risen and fallen about every five years.

    Why don’t we call it weather?

Comments are closed.