To Paul K, along with Joe’s comment, the bit about two “500 year floods” in just 15 years seems a bit telling.

On the other hand I just moved back to the midwest from Ohio. Besides the decades that I have lived here, I know more than a few people who’ve been here there entire (50+ yr) lives. All of which is perfectly irrelevant, which is perfectly obvious to anyone with even a little background in logic, because it is an appeal to annecdotal evidence. Since you would seem to hold yourself up as an exemplar of logical reasoning, it rather beggars the imagination why you would presume to stoop to such a cheap rhetorical stunt.

Alsao, the longer range prediction is for more, on average, precipitation. Much of that increase will simply fall back into the oceans.

This was a 500-year flood, much as 1993 was. How is that possible? it’s called climate change.

In fact, as this very report shows, there has been any clearer increase in intense rain fall during the. Most intense warming.

http://geosci.uchicago.edu/ ~rtp1/ ClimateBook/ ClimateBook.html

and his paper (with co-authors) with the pdf filename of CaltechWater.pdf.

If aerosols, dust, bactria, whathaveyou, is not present, the clouds, which have already condensed out of the air, cannot form percipitation. There may be aspects of temperature and pressure involved as well, but I don’t know.

So first clouds are required. A mass of air, containing water vapor, is lifted aloft by one or another process, usually convection. As it rises it becomes less dense and cooler. Eventually it becomes so undense and cool that some of the water vapor condenses into clouds.

The clouds may persist or become precipitation. Locally, either may happen, with more clouds and more precipitation at the higher elevations to the east.

Globally, it seems that precipitation has not changed in 28 years, but there is somewhat more than 52 years ago. I’m under the impression (perhaps mistaken) that the cloudiness hasn’t changed much.

For any more details, you’ll need a better source.

Thanks to David for the additional info about the aerosols. Please (seriously, as opposed to my earlier “jumping the snark”) correct my understanding here if necessary: if the moisture is not there nor the temperature differential, no natural amount of aerosol will trigger significant precipitation? On the other hand, in the presence of ordinary (”natural”) levels of aerosols, air that is unusually saturated with moisture that encounters relatively cooler air will be far more likely to produce extreme precipitation (the moisture has to be there). I.e., ceteris paribus:

Warm(er) moist(er) air encountering cool(er) air is far more likely to produce extreme precipitation than one would otherwise expect were less warm, less moist air to encounter equally cooler air? And one would expect that moisture to be more likely to come out (again, ceteris paribus) upon encountering relatively cooler air, as opposed to air of the same approximate temperature? Is there an algorithmically stable trade-off between temperature levels and aerosol content? I.e., can “we” track in a fairly direct manner the likelihood of precipitation against varying levels of temperature and aerosol differentials between moisture laden air and that which it is encountering? (I think I might be asking for a citation to a good meterology textbook.)

(By the bye: I did not mention aerosols in my earlier post but, given the ceteris paribus, any reason to believe natural levels of aerosols over the midwest and its relevant feeder rivers and tributaries, have shifted significantly of late? Particularly since the near term results of the air quality legislation of the ’70’s led to a significant reduction of non-natural contributions?)

Which wasn’t quite what you wrote.

Paul K — All other things being equal, warmer air holds more water vapor. Hence with global warming more extreme precipitation events are to be expected.

1. Warm air lofts more moisture.
2. Warm moist air becomes precipitation when it encounters cooler (and hence, drier) air.
3. Global warming predicts that there will be shifts in precipitation patterns, including the lofting of significant volumes of moisture.
4. Nevertheless, “It is sophomoric to pretend there is a connection [between global warming and the midwest flooding], especially when the floods are in an area that is measurably cooling.”

1 through 3 would seem to argue — almost demonstrate — that flooding is exactly what you would expect in an area that is measurably cooling, since that is one of the areas that will receive unprecedented precipitation from the excess moisture in the air.