Dr. Lawrence Cahoon on Hurricanes in relation to Global Warming, Cooling Effects, and Strength Reduction from Offshore Wind Farms.

Dr. Lawrence Cahoon on Hurricanes in relation to Global Warming, Cooling Effects, and Strength Reduction from Offshore Wind Farms.

1. Dr. Cahoon was invited to review recent articles related to:

– Offshore Wind Farms and weather control, mainly Hurricane strength reduction.
– Cooling effects of Hurricanes in relation to Global Warming.
– Drought conditions in Texas and California in relation to current Wind Farms.

2. Dr. Cahoon was asked to provide his scientific input on the below question:

– Do Hurricanes produce a cooling effect that adds to the reduction of Global Warming?
– Would Offshore Winds Farms decrease the strength and impact from Hurricanes?
– Do Wind Farms in Texas and California have an impact on drought conditions?

The below is Dr. Cahoon’s response:

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OK, I see some fairly major issues here.

First, the cooling effect seen with hurricanes is a lowering of sea surface temperature caused by upwelling. Hurricane winds blow counterclockwise around the eye. As they set the ocean surface into motion, Coriolis force deflects the flow to the right in the northern hemisphere, meaning that surface water is deflected away from the eye, which causes upwelling of deeper water toward the surface within the eye. Ocean waters are typically stratified, with deeper, colder water underlying warmer surface water, so upwelling replaces warm surface water with cooler water. That process is simply a displacement of heat, not a net cooling, and certainly not on a scale that supports an inference of global cooling. We have learned a lot about hurricanes and ocean temperatures – the key is the heat profile with depth, which surface buoys and satellites can’t see.

Hurricanes are gigantic heat flux engines. The trick is that it is mostly latent heat that is exchanging, generally not so much sensible heat. Latent heat is the energy required to effect changes of state without changing sensible temperature. Thus, it takes 540 calories to evaporate a gram of water without changing its temperature. That heat is released when water vapor condenses back into liquid water. In comparison it takes 1 calorie to raise the temperature of 1 gram of water by 1 degree C. As moisture (water vapor) is advected upward in a hurricane, the release of pressure with altitude causes adiabatic cooling (rising gases expand and expanding gases cool), so water vapor concentrations become supersaturating and you get condensation (rain), with the latent heat released again high up. Some of that heat radiates out into space, but the horizontal travel of hurricanes really acts to transport most of that heat from the tropical ocean toward the poles and over land. As massive as hurricanes are, their effect on global heat fluxes is pretty small on time scales longer than days, so hurricanes do not counteract global warming significantly. They are, in fact, a result of it, to some degree. Bear in mind that ocean heat content alone does not cause hurricane formation, it only adds power when a storm forms from atmospheric conditions being just right. The studies show that for the most part hurricane numbers have not changed much, but that hurricane power (integrated energy flux) has risen dramatically.

I have seen some calculations on wind farm effects on weather. Basically, the energy transduction is not really big. A gigawatt size wind farm (bigger than the Brunswick nuclear plant with a third unit on line) would be extracting a fairly small percentage of total wind power in the region. Moreover, when storm winds exceed a certain speed, wind turbines are designed to stop and even lose their rotors, as the drag on the tower would otherwise threaten to tip the whole thing over. It’s cheaper to replace the rotor (blades and hub) than the tower as well. So, wind farms aren’t going to do much to weaken hurricanes from a practical standpoint. From a theoretical standpoint, the mismatch  in total energy flux is stupendous.

Recall our discussion a while back about solar flares? Same idea. A solar flare that actually hits Earth (top of atmosphere; most of them miss) fluxes about 0.001 Watt per square meter for the duration (minutes-hours). Solar radiation in total is hitting the top of the atmosphere at about 1366 Watts per square meter 24/7/365. Total mismatch. Same for wind farms and the wind field.

Droughts in Texas and California have absolutely nothing to do with wind farms. The energy flux mismatch is, again, enormous, so big as to be impossible even with an order of magnitude or two more wind farming. The driver for drought is persistent high pressure, a function of the global Hadley circulation, in which air is heated, rises and is dewatered around the equator, moves poleward, cools at altitude, sinks in the mid-latitudes, and heats adiabatically (a sinking air mass experiences greater pressure and warms up as it compresses), which makes that air 1) warmer and drier and 2) capable of evaporating and holding more moisture. Texas and California (hell, most of the US southwest and northern Mexico) have always been semi-desert for this reason and are consequently projected to get worse for that reason as global warming fluxes more heat through the system. The Sahara is the textbook example of all this. The Middle East is largely much the same for the same reason. Climate models have predicted for many years, and rather accurately, that these mid-latitude areas will get hotter and drier, and this is why.

I hope this is all helpful. I can elaborate if you wish.

Larry Cahoon

Lawrence B. Cahoon, Professor
Biology and Marine Biology
University of N C Wilmington

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Comments

  1. working on solution to global warming

    involves capturing/creating/controlling and dissipating hurricanes. uses a 20 mile diameter circular structure floating in the ocean with fountain structures on the outer edge that shoot water out at over 100mph controlling where the eye wall starts (above the structure).

    1. i’ve been told it should work but have no way to know how many structures i need or how much heat a category 5 hurricane would emit into space.

    2. would efforts to “turbo charge” the hurricane increase the heat being ejected into space. shooting the water out at increased speed and/or heat. increasing the amount of water by using more fountains. installing a steel mill or steel manufacturing plant in the middle of the structure adding significant heat into the middle (eye) of the storm.

    3. how is it cooling the earth? i’m just an inventor but i’m guessing the water in the eye wall turning to ice ejects the heat and sends it off into space??

    website is dedicated to this
    latest video description: https://www.youtube.com/watch?v=TWzmU8aLl7k
    (please excuse quality – broke, alone and handicapped )
    541-543-7548

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