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Artificially increased rainfall ?

  1. Dec 15, 2012 #1
  2. jcsd
  3. Jan 9, 2013 #2
    "This "lake effect" could overwhelm flood defences which are often built without taking it into account." is the claim.
    The reservoir IS the flood defence.
    I would like to see how the Law of Conservation of Matter is circumvented here - a reservoir cannot hold enough water that the evaporation could produce enough rain to overfill the reservoir. It is the same thing as running a generator to produce the electricity to power the motor that keeps the generator going.
  4. Jan 9, 2013 #3
    Perhaps this extract from the article might explain it

    They seem to be suggesting that rainfall that otherwise might not occur is initiated by evaporation from open water, not that this evaporation supplies the precipitation.

    However the purpose of posting was to initiate discussion.
  5. Jan 10, 2013 #4
    Any child who has lived on the plains can tell you that thunderstorms are triggered by updrafts - humid air rising in "thermals", usually over warm dry ground. The circulation develops from the Coriolis forces applied to the updraft by the rotation of the earth. Other children raised in beachfront towns like half of California, where *everything* is along the boundary between water and land, will say "what is a thunderstorm?" Onshore winds are not readily able to form convection columns.
    The only weather that concentrates along the beaches and lakeshores are lake effect snows and fogs.
  6. Jan 10, 2013 #5
    I don't know if the thesis of the article has merit (total or partial) or not.

    I'm sorry you are not able to discuss the matter in a rational and scientific manner.

    go well
  7. Jan 10, 2013 #6
    Umm. That's not true.
  8. Jan 10, 2013 #7

    D H

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    There's a lot here that is not true.

    That's not true.

    The reservoirs behind large dams exist primarily for irrigation and hydropower. The dam and reservoir provide zero defense against flooding from rivers and streams that feed into the reservoir. Defense against these floods includes drainage systems and smaller dams. Building these flood control mechanisms to withstand a rainfall amounts based on historic records might not provide sufficient defense if the large reservoir significantly increases precipitation.
    That's worse than not true. It's a red herring.

    That's not true.

    You're talking about an air-mass thunderstorm. That's but one cause of thunderstorms, and these air-mass thunderstorms are the least severe of thunderstorms.
    That's not true.

    Tell that to residents of Florida, who regularly have to batten down the hatches against the most extreme kinds of convection currents (hurricanes) and who are hit by lightning more than anywhere else in the US.

    So, back on topic: There is a growing amount of evidence that large reservoirs do effect the local climate, particularly Mediterranean, arid, and semi-arid climates.
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