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Pollution in thunderclouds increases global warming

Discussion in 'Environmental Discussion' started by zenMachine, May 21, 2012.

  1. zenMachine

    zenMachine Just another Onionhead

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    Thunderstorm clouds - known as deep convective clouds - are an important part of the climate cycle. They reflect a lot of the sun's energy back into space, trap heat that rises from the surface and return evaporated water back to the surface as rain.

    Previous work has shown that when it's not too windy, pollution leads to bigger clouds. This occurs because more pollution particles divide up the available water for droplets, leading to a higher number of smaller droplets that are too small to rain. Instead, they ride the updrafts higher, where they freeze and absorb more water vapor. Collectively, these events lead to bigger, more vigorous convective clouds that live longer.

    http://m.tgdaily.com/sustainability...ion-in-thunderclouds-increases-global-warming
     
    #1 zenMachine, May 21, 2012
  2. austingreen

    austingreen Senior Member

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    I'm all for studying the clouds and aerosols for contribution to climate, but I'm a little confused as to the conclusion.

    It doesn't sound as if they collected enough data. It goes against my gut feel, which means I would like more data. The more clouds we get over the summer, the cooler it is. I will be happy to change my outlook with data, but this would need to be data for a season not just individual days or weeks.
     
    #2 austingreen, May 21, 2012
  3. zenMachine

    zenMachine Just another Onionhead

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    http://www.bitsofscience.org/thunderstorm-clouds-increase-warming-5976/

    Studying Chinese summer thunderclouds the researchers found that an increase in aerosols led to larger and more persistent convective cloud systems, with larger anvils at several kilometers of altitude that may reflect more sunlight, but trap even more heat – as their high-resolution model showed...

    ... In their Geophysical Research Letters publication the researchers also write that ‘aerosol invigoration effect occurs mainly in warmed-based convection with weak shear ‘ – as they could not find similar effects in frontal convection weather systems, which have higher wind shear and where air is forced up not by land surface warming, but by a pushing cold air wedge. (As case study for such weather systems they used observations of Oklahoma cold fronts.)
     
    #3 zenMachine, May 21, 2012
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  4. wxman

    wxman Active Member

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    It may be addressed in the full paper, but none of the write-ups on this study that I've seen have offered an explanation as to why cloud debris from diurnal air mass ("pulse") thunderstorms cause this net warming while cloud debris from organized convection doesn't. Organized convective events typically create an extensive cloud debris field ("blow-off") while pulse storms generally do not produce long-lived debris fields.

    It's been my experience that cirrus typically depresses temp maxima during the day more than it increases temp minima at night.

    One thing that I do agree with however is that convective parametrization in climate models (and NWP models for that matter) is woefully inadequate.
     
    #4 wxman, May 22, 2012
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  5. drinnovation

    drinnovation EREV for EVER!

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    I don't put much weight into these simulations studies. I worked for NASA goddard a long time ago on climate models and in particular on estimation of cloud cover. The the simulations produce what the mathematical models include in them. And for most of the models the sensitivity to parameters is much higher than the output variations observed given the changes being considered.

    The area of cloud cover of thunderstorm anvils top is so small compare to overall cloud cover that unless the could also account for the rate of change of other cloud formation (pollution can support both increased thunderstorm and high-altitude as well as frontal system clouds, it cannot capture the balance of energy impacted.
     
    #5 drinnovation, May 24, 2012
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