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.”
I don’t know about aerosols, but that is one wicked looking storm.
This would imply a very short life cycle for aerosols.
Don’t have any aerosol observation on the NW Ca region. What does hold up is each winters run of storms cycles with a particular phase range of the Moon, lasting 10-14 days. In some really bad years, you get a double whammy, with (for example) a storm series going from New Moon to Full, followed by another one from Full Moon to New Moon, or no cycles (76-77 drought).
Maybe they’ve found statistical evidence that people pray for good weather for the weekend.
Sounds nice an neat but the devil is in the details and the details are not given. I cringe every time I see statistically significant and no values. Sorry but we see way to much of this stuff and in the end it is effectively meaningless.
This implies that some increases in extreme weather can’t be reflexively blamed on CO2.
I assume this a joke to demonstrate how correlation proves nothin
I live in a Colorado resort community. It always seems we get a lot of storms on Thursday evening. Convenient, conicidence, effective cloud seeding programs or just that I have band practice on Thursday evenings? For the resorts the timing couldn’t be better. Everyone in the Denver metro area wakes up on Friday morning already thinking about the weekend and then they get a great snow report. Yes, some of the resorts waste millions on cloud seeding programs.
just by chance, over 70% of the time the storm will occur on a weekday. Reminds me of the manager’s complaint against a worker. “You’re a slacker, kid, whenever your sick, 40% of the time it’s on a Monday or a Friday”
Hit me in the head with a frying pan BUT it seems to me we would need hot and cold fronts to achieve heavy weather to begin the process. Now to me at least it is worthwhile then to think aerosols are in the atmosphere at somewhat the same level and with storms that do not produce severe weather the vast majority of the time. That is unless humans in the weather path all watch the sky and whenever they see clouds roll in everyone starts spraying their favorite fragrance in a continuous fashion resulting in human induced heavy weather. Yeah – that seems on a par with aliens invading due to human global warming universal concerns not to mention weren’t we all responsible for the holes in the north and south poles due to aerosols that seems to have disappeared from the radar lately. Look, I get it – we go crazy with global warming – so crazy we’re branching out and blowing up stars these days. The aliens have to be crazier than us taking earthlings on ’cause we’ll blow up their star next if they mess with us. Excuse me for asking – but what are we spraying to cause the droughts?
Is this saying humans can have an influence on the weather?
This also implies that humans are cooling the earth (land)?
Maybe the anthropically generated aerosols [i]add[/i] to the bad weather but are not necessarily [i]causative[/i]. The blame for the 7-day week, if my recollection serves me well, is attributed to the Babylonians. They were highly observant astronomers and consequently well aware of the length of the lunar month but they could just as easily have established 7 4-day weeks or even 2 14 day weeks, as 4 7-day ones. Perhaps a 7-day weather cycle even back then, was the deciding factor …
Now I understand. Now I understand! I thought fly spray killed flys, but because I use an aerosol fly spray, that causes it to rain and the drops hit the flys and kill them. That is why there are fewer flys around in wet weather!
Seriously, I agree with Dr A Burns. This implys that aerosols are so short lived as to have a 48 to 96 hour life yet they are also travelling all the way to remote regions? Could it not be that activity causes more heat, hence more convection etc etc. What’s up with that?
The paper includes the following statement
QUOTE
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.
UNQUOTE
I was under the impression that the level of storms has fallen over the last 50 years, relative to the previous 50 years.
Am I mistaken?
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!
[sarc]
Weather is controlled by cock crows. That’s settled common knowledge I was told already by my granny. The really haunting problems are elsewhere. Lack of education? See for example
http://carm.org/bible-difficulties/matthew-mark/did-cock-crow-once-or-twice-peters-third-denial
If we don’t solve that soon, anything may happen. Anything! I tell you.
[/sarc]
‘Science’ plumbs new depths. The old saying has never rung so true, “There are limits to everything, except stupidity”
Roger Sen. seems confused as to the difference between climate and weather. All these events described are weather. Humans would have to do far more than produce a few aerosols to affect climate.
On reflection, this is a shocking finding and just emphasises that our worst fears are being realised (or something).
Is it possible to slap a tax on those wicked people who keep shooting dirty airy-solles into the air?
Or is it level airoplanes or what?
Anyway, it’s a disgrace and summthin shud be dun abit.
There – I’ve had my sayeeee.
Nice sounding paper. I’m tempted to believe it actually went through some sort of pal-review.
There is the answer to drought hit lands. Give everybody in the land an aerosol and tell them to al spray together, into the air at 1pm. Resulting shortly after in one hell of a storm, and lots of rain. Mind, is that going over the top. We don’t want to create a flood.
In short though with the article. What a load of tosh as we call it here. I see someone else looking for more funding coming out the woodwork.
Completely off-topic, but it cries out for a wider audience!
[snip – and here is not the place for it – post in Tips & Notes ~jove, mod]
If there is no wind do the storms stay for the weekend? If during the week, when the wind is from the sea, do the storms go away? Are Sundays “statistically” less stormy than Saturdays (because there must be a lingering period for the aerosols to dissipate) ? And how about Monday – Tuesday – surely it takes time for the aerosols to build up after a weekend of low emissions?
This reminds me of a great film called drowning by numbers in which Tuesday’s were said to be the day on which the most violent deaths occurred