Gang Aft Agley

Willis, thanks for your interesting and insightful posts, and may you have safe journeys. Your mention of virga prompts me to put here as a comment a post I composed a couple months ago on social media. I know it’s a bit long. It astounds me how so many otherwise capable folks – scientists or otherwise – can buy into such an obvious (to me) misconception about how the atmosphere works. I address the global warming issue as an old-school mechanical engineer who started with a slide rule.
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I was in Mr. Heinrich’s geometry class in high school. Great teacher. So does geometry matter? Is it reliable?
Can geometry help us examine the “global warming” hypothesis? Let’s illustrate with a geometry exercise. It’s a long post, but please read on if you are curious and wish to consider this question from an alternative viewpoint.
About one meter (40 inches) of precipitation falls per year, averaged over the globe. This is one cubic meter of volume per square meter of surface. Raindrops are 2.5 millimeters in diameter, more or less. From geometry, one calculates that the surface area of all the raindrops in one cubic meter of water is about 2400 square meters. Hold that thought.
The global warming claim is that the lower atmosphere will heat up as concentrations of carbon dioxide and other “greenhouse gases” increase, absorbing more of the heat emitted upward by the earth’s surface. Then the warmed atmosphere emits more heat back downward, warming the surface. That’s the hypothesis. The geometry of this claim is one square meter looking up from the surface, one square meter projected downward from the atmosphere, as heat is radiated upward and downward.
But wait. The atmosphere does not actually work like that. The radiative emission and absorption of heat is in every direction from every location, not just up and down. In our illustration, as raindrops fall from cooler conditions higher up through warmer conditions down low, a huge surface area is exposed to the atmosphere for heat to be exchanged. Over a year’s time, this is 2400 square meters, on average, per square meter of earth’s surface! This geometric advantage applies to all forms of heat exchange between raindrops and the lower atmosphere: radiative, direct contact, and evaporation. The heat transfer happens rapidly as raindrops experience a stiff breeze as they fall by gravity. So just as the oceans and land surfaces are cooled by evaporation, convection, and radiative emission, so also is the lower atmosphere itself cooled, even more intensively as this geometry exercise about raindrops illustrates.
So what will an increasing concentration of carbon dioxide do? Logically, it will simply increase the effectiveness of the radiative part of the heat transfer between raindrops and the atmosphere. But will it change the temperature of the atmosphere? This is not plausible, as the fixed properties of water such as vapor pressure and latent heat of evaporation already exert such complete control over the temperature resulting from this intense interchange. Furthermore, if carbon dioxide increases the radiative effect downward near the surface, then logically the radiative effect is increased outward to space higher up where condensation occurs. Water vapor is recycled back up to condense again and form raindrops to fall back down to the surface, easily counteracting any tendency of “greenhouse gases” to change the resulting temperature down low. This happens without even implying any net change in rainfall reaching the surface. The atmosphere determines for itself how much of each raindrop makes it to the surface. We only measure the remainder. We don’t measure what doesn’t reach the surface, therefore it cannot have been modeled accurately enough for computers to tell us anything useful about it. But we can grasp what must be happening as we observe the rainfall and apply the geometry and the properties of water to this question.
So here’s the bottom line of this illustration: Some say “Dangerous carbon pollution!” “Climate catastrophe!”. But in reality, the atmosphere knows exactly what to do to control its own temperature, and will do it reliably using water as the vehicle with an overwhelming advantage in surface area. Geometry rules! Thank you Mr. Heinrich.
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