In this article, Clifford Carnicom make some bold claims:
Bunk from external source:
1. Contrails composed of water vapor routinely dissipate, as the physics and
chemistry of this model will demonstrate. As a separate and distinct
set of events, clouds may form if temperature, relative humidity, and
aerosol conditions are favorable to their development. If "contrails"
by appearance transform into "clouds", it can be concluded that the
material of composition is not water vapor.
2.The conditions under consideration show that the ice crystals
within a contrail can warm to the melting point and subsequently melt
with the heat provided by solar radiation.
3. As demonstrated both by historical observation and this model, the
time expected for contrail dissipation is relatively short, e.g., 2
minutes or less. This assumes the contrail is composed essentially
of water vapor, per the classic definition (condensed trail).
If we give Carnicom the benefit of the doubt and assume most of this science is correct, then the conclusion he reaches is that:
- First the water vapor freezes, because it's so cold
- Then it melts and evaporates, because the sun is so hot
So why doesn't is just freeze again, because it's so cold? The condensation nuclei still exist, and are now considerably cooler than when they exited the engine.
He also makes the distinction between clouds and contrails, saying clouds form on smaller condensation nuclei (0.1 to 0.2 microns). To suport this he quotes Goethe MB - Ground Based Passive Remote Sensing of Ice Clouds with Scattered Solar Radiation in the Near Infrared - Max Planck Inst Meteorol, which gives a particle size of 30-200 microns. However that Goethe study is not measuring nuclei (the tiny seed at the heart of an ice crystal), it's measuring the actual fully grown ice crystals.
The condensation nuclei for contrails that come from the exhaust are basically soot and other byproducts of combustion, having a size of 0.1 microns or less.
Hence they will behave exactly the same as clouds. If carnicom has proven here that contrails cannot persist and spread, then, since clouds must start out small and spread to a larger size, he has also proven that cirrus clouds cannot even exist at all.
Then in a second article, The RH Deception
He claims that if the relative humidity is between 70% and 100% then contrails should dissipate in about ten seconds, because at 10% relative humidity it would dissipate in two seconds.
Bunk from external source:
Even at a relative humidity level of 70%, which must be considered quite high for the commercial flight domain, a factor of 3.3 against the maximum evaporation rate of a completely arid environment must be considered as relatively minor. Most of us would have a difficult case of making the argument of a persistent vapor trail within a moisture-free environment, and more realistically we would expect dissipation within a matter of seconds (disregarding deliberate aerosol injections). To multiply a few seconds by a factor of 3.3 leads to no real world change in the situation at hand
This is nonsense for two reasons.
1) Evaporation or melting time does not scale like that. It's as if he claimed that since ice melts in ten seconds at 100 degrees, and in five seconds at 50 degrees, then it should melt in about two seconds at zero degrees. Of course it's not actually going to melt at all.
2) If Relative Humidity with respect to water is between 70% and 100% then relative humidity with respect to ice is always above 100%. In that environment ice cannot sublimate. In fact it will always accrete more ice, and the ice crystals will grow bigger, causing the contrail to spread.