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Why do tornados and hailstorms rest on weekends?

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116 (2011-10-29) Daniel Rosenfeld, Thomas L. Bell

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Back on the climate change question. There is some reluctance on your part to agree with the notion that climate change is both real and largely caused by human activities. I think I can prove that this is at least a reasonable notion by another means.

1. The climate is the sum of the localized weather.
2. If you can change the weather, then you can change the climate.
3. If human activities affects the weather, then they can also change the climate.

Do you agree with the logic of those statements?

It turns out that there are MORE tornados and thunderstorms in the middle of the work week than on weekends, with the most occurring on Tuesday and Wednesday. This is not just a feeling people have because they want the weather to be better on the weekends, it is a fact.

Apparently, the weekly cycles have been known for years and these guys are trying to explain the weekly cycle as due to anthropogenic aerosols.

I don't have the text of the article bc they want $25. But you can see in the plots that hailstorms and tornados peak Tuesday & Wednesday, see fig 5 of 10 in the little box at the bottom.

Since there is no viable explanation for this correlation other than the activities of humans has an effect on weather, we must conclude that humans can also be a huge impact on the climate.

Key Points
  • Hailstorms and tornadic storms occur more frequently in more polluted moist air masses
  • Pollution aerosols can cause convective storms to become severe

Daniel Rosenfeld

Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel

Thomas L. Bell

Climate and Radiation Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

This study shows for the first time statistical evidence that when anthropogenic aerosols over the eastern United States 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 United States. Although we focus here on the role of aerosols, they are not a primary atmospheric driver of tornados and hailstorms but rather modulate them in certain conditions.


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Title Why do tornados and hailstorms rest on weekends?
Author Daniel Rosenfeld, Thomas L. Bell
Pub Date 2011-10-29
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Note Tornados and hailstorms are stronger and more prevalent during the week.
Keywords Climate Change
Media Type Linked Article
Media Group News
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Topic revision: r2 - 2012-06-07, RaymondLutz

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