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By James McGinn
A man goes to a tailor to try on a new custom-made suit. The first thing he notices is that the arms are too long.
“No problem,” says the tailor. “Just bend them at the elbow and hold them out in front of you. See, now it’s fine.”
“But the collar is up around my ears!”
“It’s nothing. Just hunch your back up a little… No, a little more… That’s it.”
“But I’m stepping on my cuffs!” the man cries in desperation.
“Just bend you knees a little to take up the slack. There you go. Look in the mirror–the suit fits perfectly.”
So, twisted like a pretzel, the man lurches out onto the street. Reba and Florence see him go by.
“Oh, look,” says Reba, “that poor man!”
“Yes,” says Florence, “but what a beautiful suit.”
It started with James Pollard Espy, the Storm King, who, around the 1840s, proposed an explanation for the power and vertical uplift witnessed in thunderstorms: moist air is lighter and, therefore, more buoyant than dry air. He accompanied his claim with an argument based on ideal gas laws that, it seemed, substantiated the claim that “gaseous vapor” was lighter and, therefore, convected up through drier air. However, the notion stood in sharp contrast to the people’s basic senses. Everybody, it seemed, felt that warm, moist air was heavier than dry air, not lighter. Additionally ideal gas laws are only applicable to–you guessed it–ideal gasses. It was well-known that H2O is not an ideal gas and, in fact, only becomes a gas above 212 degrees F, and the atmosphere rarely got above 100 degrees. Some suggested that maybe we should measure, just to be sure. But scales with the high degree of precision necessary to measure the weight of such small traces of gas were not as common back then as they are now. Espy dissuaded them from these concerns by pointing out that without this explanation we don’t have any other way to explain how moisture travels up high in the sky to produce clouds. With that everybody’s objections were overcome. The notion just made too much sense to not be correct, they assured themselves.
Then people started noticing a long flat layer no more than a thousand feet above the ground. This layer was prominent during calm weather conditions and was especially evident on the mornings of windless nights. There was no denying that the section below was the more moist, seemingly a direct contradiction to the previously agreed upon notion that moist air was lighter and would, therefore, convect up through dry air. By this time there was a whole collective of people that had followed in Espy’s footsteps. They had long since begun referring to themselves as meteorologists. Knowing their status as predictors of future weather was in jeopardy if they didn’t find a resolution to this discrepancy they conferred among themselves. One of them mentioned that the layer that sat atop the moist layer was often (not always) warmer than the layer below, itself being a contradiction to the normal tendency of air to get cooler with height. “That’s it,” one of them declared. The warmer layer must act as a cap, presenting a surface that defies the upward movement of more buoyant moist air. Others objected. Even then it was known that of the four states of matter (solid, liquid, gas, and plasma) one property that distinguished a gas from all others was that it did not have a surface and/or surface tension. However, by this time the methods of consensus were well established among meteorologists, having no other option they ignored these objections and decreed the discovery of inversion layers and ordained them as the agents of atmospheric stability.
There were, of course, grumblings with the emplacement of such an artificial notion into the working principles of the young scientific discipline. But these gradually subsided as they began to realize its residual benefits. Another observation that had been problematic for the notion of up-welling, moist air as the cause of the power and vertical uplift witnessed in thunderstorms was the observation that very often the thunderstorms happened hundreds of miles away from the warm bodies of water that produced the moist air. With its inclusion as an addendum to the greater body of meteorological theory this notion that inversion layers formed a cap or widespread barrier to up-welling, moist air provided an explanatory avenue of escape, allowing these kinds of observations to be considerably less bothersome. But some were concerned that, possibly, the greater theory was evolving into a comedy of contradictions. If the dry air that exists in abundance in the upper altitudes is both the agent of stability and the substrate through which moist air convects to cause storms then how do we convince the public–a public increasingly aware of the death and destruction associated with large tornadoes–that our understanding of storms is rooted in sound theory.
The solution kind of presented itself. It is called parcel theory. Parcel Theory is a set of abstract rules purported to indicate when and why certain “parcels” of the atmosphere remain stable or become unstable. From the perspective of any kind of practical applications, however, parcel theory has severe limitations, ” . . . since it is difficult to define how large or small a parcel really is and what mechanisms exist that selectively lift the small parcel and not the entire atmospheric layer. In addition, parcel theory fails to accommodate the fact that considerable entrainment of surrounding air occurs as buoyant plumes develop.” Ultimately what this all means is that since parcel theory is based on phenomena that is immeasurable and un-testable and since it has no practical applications to predicting or preventing storms or tornadoes it usefulness is solely diversionary. And it is most useful in this respect when directed at outsiders to meteorology who start poking around, asking too many questions, especially when it involves questions about the previously mentioned contradictions.
So, if you do come across a meteorologists, especially one focused on the sub-disciplines of Storm Theory or Tornadogenesis and they appear to be somewhat bumbling, take pity on them. Keep in mind the unseen, underlying contortions they are doing to keep their twisted suit of a theory looking presentable.
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