Hi all,
The basis of the MCB method of Salter et al. is sea water. Sea water is
a salty water with a slightly alkaline pH value above 7. The ISA method
generated FeCl3 aerosol (ISA) has an acidic pH around 2.
This are not the only differences of the methods: The ocean surface
needs an efficient cooling to prevent from hurricane developement.
Salter's method delivers this cooling only by cloud whitening. The ISA
method use cloud whitening plus several additional cooling methods like
sea surface whitening/brightening by algae, methane depletion.....
According to this much more efficient sea surface cooling the ISA method
is the better hurricane prevention than MCB.
Another article about the physics of hurricanes below.
Best,
Franz
------ Originalnachricht ------
Von: "Russell Seitz" <russellse...@gmail.com>
An: "geoengineering" <geoengineering@googlegroups.com>
Gesendet: 16.09.2018 00:49:39
Betreff: [geo] Re: Hurricane moderation
Stephen, I'd direct your editors to Kerry Emmanuel's seminal paper on
hurricane track cooling, as the published basis for considering both
hurricane track cloud nucleation and sea surface albedo modulation to
moderate strorms
On Saturday, September 15, 2018 at 4:19:10 AM UTC-4, Stephen Salter
wrote:
Hi All
I was asked to write something about hurricanes for a well known
popular news outlet but they thought that it was too technical.
However it might still be useful. I hope that the ETC group can
comment.
The formation of a hurricane depends on many factors including
atmospheric water vapour, distance from the equator and the recent
history of wind patterns. But an essential requirement is a high sea
surface temperature. To get from a tropical storm to the lowest
category of hurricane requires a temperature of 26.5 C. We can
moderate hurricanes, or even prevent them, by reducing water
temperature.
A useful start to any engineering project is the estimation of all the
energy flows. One cubic metre of air at a temperature of 30 C can hold
about 30 grams of water vapour. The energy to evaporate this is about
the same as in 13 grams of TNT, enough for a nasty anti-personnel
mine. A cubic kilometre of such air contains the same energy as the
Hiroshima bomb. Hurricanes can be hundreds of kilometres in diameter
and so contain tens of thousands of Hiroshimas. If you have read this
far you will know about the billions of lost dollars and thousands of
deaths from this amount of energy.
Most of the hurricanes that reach America (with the exception of
Harvey), start on the African side of the Atlantic near Cape Verde and
grow as they move west. We can use Google Earth to measure the
hurricane breeding area. The US National Weather Service gives a warm
water depth of 45 metres. To cool this volume by 2 C in 200 days needs
more than 600 times the mean US electricity power generation. If you
want to moderate a hurricane tomorrow, today is much too late. You
should have started last November.
All this heat has come from the sun. Some could be reflected back out
to space by clouds. The reflectivity of clouds was studied by Sean
Twomey. He flew over many clouds, scooped samples and measured the
solar energy reflected from their tops. He showed that reflectivity
depends on the size distribution of drops. Lots of small drops
reflect more than the same amount of liquid water in fewer, larger
ones. In typical conditions, doubling the cloud drop number increases
reflectivity by a bit over 0.05.
Making cloud drops needs a high humidity but also some kind of ‘seed’
called a condensation nucleus on which to start growth. There are
thousands of condensation nuclei per cubic centimetre of air over land
but fewer in air over mid ocean, often less than 50. John Latham
suggested that the salt residues left from the evaporation of a spray
of sub-micron drops of sea water would be excellent condensation
nuclei. They would be moved from the sea surface by turbulence to
produce a fairly even distribution upwards through the marine boundary
layer to where clouds form.
The condensation nuclei could be produced by wind-driven sailing
vessels cruising along the hurricane breeding areas getting energy
from their motion through the water. We can make spray by pumping
water through very small nozzles etched in the silicon wafers used for
making microchips. The main technical problem is that sea water is
full of plankton much larger than nozzles. This can be filtered using
ultra-filtration technology with back-flushing, originally developed
for removing polio viruses from drinking water. Each vessel would
produce 0.8 micron diameter drops at 1017 a second.
Spray operations would depend on the pattern of sea surface
temperatures as measured by satellites. We want the trajectory of
temperature rises through the year from November to the following July
to be those that an international panel of meteorologists think will
give a desirable rainfall pattern from ‘gentle’ tropical storms.
Most ships are made in quite small numbers. An exception was the
Flower class corvettes built for the Royal Navy during World War II.
If we index-link the 1940 cost to today we can predict that in mass
production each spray vessel would cost $4 million. With assumptions
which have not yet been rejected by hurricane experts, we think that
controlling the Atlantic hurricane breeding paths would need about 100
vessels. With typical ship lifetime the annual ownership and
maintenance cost would be about $40 million. If these figures and
recent estimates of the cost of hurricane damage are correct the
benefit-to-cost ratio is quite attractive.
Because of official UK Government policy updated in May 2018 the
project is privately funded.
I will send anyone who asks an update on recent hardware development,
still privately funded.
Stephen
--
Emeritus Professor of Engineering Design, School of Engineering,
Mayfield Road, University of Edinburgh EH9 3DW, Scotland
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