Hailstorms and tornadoes are more common during the weekday due to human created aerosols.
By Dr. Roger Pielke Sr.
New Paper “Why Do Tornados And Hail Storms Rest On Weekends” By Rosenfeld and Bell 2011
There is a new paper which further documents the diversity of human climate forcings that is presented in
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union
and in the American Meteorological Society statement on
Inadvertent Weather Modification (Adopted by the AMS Council on 2 November 2010)
The new paper is
Rosenfeld, D., and T. L. Bell (2011), Why do tornados and hail storms rest on weekends?, J. Geophys. Res., doi:10.1029/2011JD016214, in press.
The abstract reads [highlights added]
“This study shows for the first time statistical evidence that when anthropogenic aerosols over the eastern USA during summertime are at their weekly mid-week peak, tornado and hailstorm activity there is also near its weekly maximum. The weekly cycle in summertime storm activity for 1995-2009 was found to be statistically significant and unlikely to be due to natural variability. It correlates well with previously observed weekly cycles of other measures of storm activity. The pattern of variability supports the hypothesis that air pollution aerosols invigorate deep convective clouds in a moist, unstable atmosphere, to the extent of inducing production of large hailstones and tornados. This is caused by the effect of aerosols on cloud-drop nucleation, making cloud drops smaller and hydrometeors larger. According to simulations the larger ice hydrometeors contribute to more hail. The reduced evaporation from the larger hydrometeors produces weaker cold pools. Simulations have shown that too cold and fast-expanding pools inhibit the formation of tornados. The statistical observations suggest that this might be the mechanism by which the weekly modulation in pollution aerosols is causing the weekly cycle in severe convective storms during summer over the eastern USA.”
Excerpts from the paper read
“The results are in agreement with our previous reports of similar weekly cycles in the rainfall [Bell et al., 2008] and lightning [Bell et al., 2009a] over the USA. The cycle was ascribed there to aerosols invigorating deep convective clouds in a warm, moist atmosphere. It is therefore not too surprising to find that the invigorated clouds also produce more hail and tornados.”
“This study has shown a clear correspondence between the weekly cycle of anthropogenic aerosols and the occurrences of severe convective storms, which is highly unlikely to be a result of natural variability. The observed associations cannot serve as proof for causality. However, the results are consistent with the hypothesis that air pollution aerosols invigorate deep convective clouds in moist and unstable atmosphere, and the possibility that they can even induce the storms to produce large hail and tornados. This is also consistent with the hypothesis that the severe storms are better organized and violent because aerosols increase the hydrometeor size, decreasing their evaporation and so weakening the negative buoyancy of the downdrafts, thereby preventing the gust front from outrunning and undercutting the updraft in the feeder clouds. Anthropogenic emissions have caused large enhancements of aerosol loads even over the remote continents, with typical enhancements of 50–300% over remote regions of Asia, North America, and South America (Wilson et al., 2001; Chin et al., 2004; Park et al., 2006; Stier et al., 2006).Regarding this increase, it is worth pointing out that if a roughly 10% weekly variation in pollution levels is resulting in a similar change in severe storm activity, then the “background” aerosol level, which is elevated with respect to the pre-industrial level even during weekends, is also likely to be changing the storm frequency that we experience today.”
Not O/T, I have the most fascinating navel…
So people going to work are causing the bad weather? And I though it is always bad weather on weekends. Maybe grilling in the garden creates too many aerosols, or only the plan to grill some sausages is enough?
Or maybe it is another man made effect – possibly in the way that there were less people on duty during the week-end to record data?
Interesting, the forecast for this weekend in New-York is storm & rain for Saturday & Sunday with clear sky for most of the coming week but that must be only weather or they work only on week-ends in New-York?:
http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=New+York+City%2C+New+York
Why wouldnt Friday have the maximum Aerosol level? (aka midweek maximum)
Have Wednesdays been measured to have maximum Aerosol or is this just assumed.
George Lawson says:
August 27, 2011 at 1:07 am
As there happens to be five weekdays and only two weekend days in any week, isn’t it statistically obvious that any weather will be two and a half times more during the week than at the weekend!
========================================================================
Bingo!
Just like those mercury ridden low watt light bulbs. If we all used them it would be as effective as throwing a sugar cube into Loch Ness to make the water sweeter. Ir depending on wind turbines only for electricity when the wind don’t bloweth and solar panels when dat sun donna shine.
Did a bit of research on this my self.
Of the last 1000 storms 715 occurred on week days and only 285 on weekends.
I could not believe my findings. There are 250% more storms on week days compared to weekends. This research must be correct. Unbelievable.
No wait 715/5 = 143, 285/2 = 142.5
Yes the original data is correct. There is 0.5 more storms per day through the week as compared to a weekend.
A grant is needed to research this further.
Well, I’m doing my part to mitigate the weekday aerosols.
My weekday commuting is offset by my weekend lawnmowing, leaf blowing, motocross, and barbequeing.
My efforts however, and those of countless others, may be fruitless because invisible aliens may be altering weather patterns without us realizing it. Someone should apply for an NSF grant to study this.
Michael Mann has graciously prepared the graph for the final report in advance for us.
Clearly the researchers haven’t spent anytime in shore traffic on the weekend.
This looks like another attempt to shut down an entire industry.
Very interesting — I assume that they found a small, but statistically significant difference in the frequency per day, and it’s plausible that this is caused by human-generated aerosols.
But even so, are the aerosols just triggering severe storms that would have occurred randomly otherwise, so that the number of severe storms is about the same as it would have been without the aerosols?
Or, are they causing severe storms to be triggered earlier than they otherwise would be, so that they are actually less extreme than they would be if they were allowed to build up naturally to full force?
Correlation does not prove causation.
Fork over my stimulus grant money Mr. Biden!!
Headline: Research shows that aerosols cause weekdays.
What type of aerosol is widely used in this studied area? Can hairspray be blamed:-)
Mid-week isn’t the cumulative maximum for aerosols–it would be Friday or Saturday (the accumulation of 5 days even if a significant number of people curtail business activity on Friday). I’d say this study is suspect if they find mid-week (Wednesday) to be the day of maximum storm activity.
Holy @&*%! That is an amazing picture.
Interesting paper, too.
I want to know what happened to the photographer who took the picture of the storm. Is he still with us?
It was quite common back in the late 1960s for the summers to be clear during the weekdays and then rain on the weekends. Basically, it took 4-5 days for the aerosols to build up and then rain would form and clean the air.
This pattern was truly a pain in the ass as I was dating a girl at the NJ shore and studying in Rochester, NY. I would drive down on Friday and back Sunday and had 10 weeks of rainy weekends—did not go to the beach once! The movies back then did not turn over that rapidly and there were few places to eat.
@ur momisugly Gator says: August 27, 2011 at 5:24 am. The word that you are looking for is omphaloskepsis.
Dr. Pielke Sr. has been saying for years that increased CO2 is not man’s only influence on weather/climate, and that man’s other changes to the physical environment have at least as much, if not greater effect. On the other side we have the CAGW ‘Team’ that, in dozens of published papers, has been trying to ‘prove’ scary increases in the both frequency and strength of hurricanes, tornadoes, and other weather events, all caused by increasing CO2. However, upon closer examination, the statistics of the Team seem to always fall apart.
If it stands, this paper will, as far as I know, be one of the few to actually support the theory that man has any effect at all on weather/climate on anything other than a very localized scale. And, it supports Dr. Pielke Sr.’s side of the argument over the ‘Team’s’.
Really good point about the residence time of aerosols if you can see a mid-week to weekend difference in hail storms (causative). And what does “statistically significant” mean? That if you don’t use computers and algorithms you won’t see the correlation?
That’s the second “good” point. Only math says there is a signal inside natural variability. And the residence time is so short that the other dumb idea, that the aerosols from Chinese coal-powered power plants stopped global warming 10 years ago.
Speaking of which: China has been building and putting on-stream coal-fired plants every month for about 18 months now, with at least 48 in the line-up. If China really is affecting the weather, the global temperatures will actually DROP over the next few years.
Again, it is not natural. Global warming, at least the Chinese type, will result in global cooling.
Unfalsifiable again.
They really need to do indepth day to day met analysis before they can come to that conclusion. Especially when they say…”The observed associations cannot serve as proof for causality.” Are there more in the way of naturally strong fronts during this period due to the natural rhythms of weather patterns we can fall into?
14 years * 20 weeks( or whatever the number of weeks that are considered summer storm weeks) does not provide many cycles to analyze.
“possibly in the way that there were less people on duty during the week-end to record data?”
Lars, you cracked me up man.
This report is nothing more (or less) than saying that extra aerosols injected into the atmosphere tend to lead to increased storm activity – at least with respect to hail and tornadoes. What is the difference between this and Cloud seeding ? which is known to have a slight increase in inducing rain or storm activity. What the authors appear to be saying is pollution does produce similar results. Saying that man can have no affect on weather is disingenuous in the least – after all people have been trying to affect local weather for generations. Humans can indeed effect changes in local climate – cities are warming than the countryside, deforestation can lead to desertification of areas (Cedars of Lebanon – where are they now?), and so on.
This has little to do with GHG or other claims by the warmists, but does show that man can have an effect and these must be studied to understand how to account for them in local weather and climate.
Personally I think the juxtaposition of this study and the recent CERN experiments with cloud creation are fascinating and should be accepted (if non-falsafiable) as yet another data in the understanding of our environment and how we interact with it.