As the weather around the world reaches new extremes the big challenge will be to try
and mitigate the effects of climate change by changing the way we create and use energy,
transport and food production. But could there be other ways using the technology we have
today to try and reduce the size and energy of some of the more localised and destructive
weather events like Tornados and Hurricanes? and control rainfall.
Controlling the weather or weather modification as it known has long been the goal of many,
from those wanting to make things better for their fellow man but also those that want
to make it somewhat worse by looking to weaponize the weather and it’s not as if we haven’t
been trying. One of the most well-known methods of weather
modification is cloud seeding, this is basically spraying tiny particles like silver iodide,
dry ice or frozen carbon dioxide, liquid propane and more recently table salt into the clouds
by planes, rockets and flares. Although this method has been done of over
70 years there is still a lot of debate as to how effective it really is but in what
was called the most scientific study of cloud seeding carried out so far in Wyoming over
a six year period seeding mountain clouds, it was concluded that it produced about a
10% increase in precipitation but equally that different areas and conditions around
the world could produce more or have no effect at all.
There are two basic methods, the cold rain method, and the warm rain method.
The cold rain method works in more temperate areas where large convective clouds contain
supercooled water. The seeding agents like dry ice provides nuclei for the supercooled
water to freeze around which then travel on updrafts in the cloud picking up more water
and growing larger. When they are large enough they fall and melt into rain on the way down.
If a storm is very large and has strong updrafts they become so large that they don’t melt
on the way down and fall as hail. The warm rain methods is used in tropical
areas where the clouds don’t reach the freezing point, so a hygroscopic seed, that's one which
absorbs water like salt is used instead. The tiny droplets coalesce as they also float
on the updrafts again until they are heavy enough to fall as rain.
However, if too much seed material is used it can have the opposite effect by creating
too many seeds for the amount of water vapor available so very few of them can grow large
enough to become raindrops and here we have another underlying issue.
Natural rain requires a seed to start the process which could be a particle of dust
or pollen but our use of fossil fuels, especially diesel and coal also creates a lot of soot
which can also act as a seed, so just driving your car or putting your heating on, you could
be unintentionally seeding the clouds. This pollution has been blamed for the loss
of the snowpack in recent decades in areas like the western US which that rely on clouds
forming over mountains and the snow they deposit and for the meltwater for their water supplies.
If the clouds are seeded by pollution before they reach the mountains there would be less
snowfall and less water, so seeding clouds over the mountains is seen as a way to bring
back the snow and increase the water supply. Another experiment using ionised particles
is being trialed in the middle east in Abu Dhabi. The idea here is that the negatively
charged particles are released from Ion-emitters and float upon convection currents and attach
themselves to the natural condensation nuclei in the clouds. Once charged they would to
attract other nuclei and grow more quickly and hopefully survive longer to produce more
rain than would have possible without being charged. So far they say it has had positive
results but more research is required. A common misconception is that cloud seeding
can create rain or snow will anywhere and from clear skies, this is false. It can only
affect clouds which are already rain or snow bearing or that just at the point of becoming
so. If there are no clouds or clouds that can not produce rain such as the very high
cirrus clouds, then no amount of seeding will make any difference. It has also been found
that clouds that form over the sea are more likely to respond to seeding compared to clouds
that form inland. Hail suppression is another reason why seeding
of large thunderstorms is done in parts of the world where hailstones routinely grow
to very large sizes and cause damage to crops, vehicles, buildings, and people. Although
the exact details of how hailstones in these storms grow are still sketchy, the idea is
that seeding them will cause more of the supercooled water to fall as rain earlier and reduce the
amount that is available for hailstones to form and thus reduce their size.
In fact, is been found that the tips of the propellers of aircraft and the airflow over
their wings can also produce ice particles from the clouds water vapor under certain
conditions and unintentionally seed clouds which could be wrongly attributed to a seeding
agent. But this hasn’t stopped many countries around
the world from trying it. China has invested heavily in cloud seeding and even used it
to try and keep the opening and closing ceremonies of the 2008 Beijing Olympics rain and smog-free.
Whilst China says that they have had great success it also has some of the most polluted
skies in the world further confusing the results. Its been reported that they had deployed over
solid fuel 500 burners on the high slopes of Tibetian plateau to pump out silver iodide
in an experiment to increase the amount of snow and rain across a 1.6 million square
km area that eventually feeds in to the Yellow, Yangtze, Mekong rivers even though in the
west silver iodide is increasingly seen as a pollutant and therefore is not used much.
But as they say, one man's pitchfork is another man's weapon of war and so it was with cloud
seeding in the Vietnam war when the US carried out the secret CIA sponsored operation Popeye
from 1967 to 1972 under the auspices of weather reconnaissance. This was an attempt to increase
the length of the monsoon season with cloud seeding with the intention of causing damage
due to extra rainfall to roads, river crossings, inducing landslides and generally making life
more difficult with year-round mud for the Vietcong along the Ho Chi Minh Trail, the
main route for transporting men and arms to the South but which also covered parts of
Cambodia, Laos, as well as Vietnam. Only after the programs existence was leaked in 1971
did operations cease in 1972 after details of it were published in the New York Times.
This highlights the issue that the effects of increased rainfall don’t stay in the
area where the seeding took place or the rain fell. Flash floods along river courses could
happen far from the rainfall and even in other countries.
So if we could affect rainfall then we should be able to affect storms and the biggest of
all, the tropical cyclone or hurricanes. Project cirrus was a collaboration between the US
Army Corp and General Electric to drop crushed dry ice or frozen carbon dioxide from a modified
bomber into the rainbands of a hurricane in 1947, this is actually the basis of all modern
cloud seeding. The theory was that the dry ice would cause
a new eyewall to form which would be larger than the old one, this would reduce the pressure
gradient and weaken the hurricane. After the seeding, the storm which was traveling westwards
did a quick turn and made landfall near Savannah, Georgia. People blamed the change of direction
on the seeding and legal action for the damage caused was threatened which stopped further
trials for over 10 years. Later it was discovered that a similar storm had done the same thing
in 1906 and that the 1947 storm was probably already turning before the seeding started,
this stopped the legal action. Project Stormfury was a further attempt weaken
hurricanes run by the US government from 1962 to 63. Again this used cloud seeding but this
time with silver iodide which mimics the effect of the dry ice whilst being easier to handle
and longer-lasting. This was to try and make the supercooled water in the hurricane to
freeze and disrupt the it’s inner structure. However, it was found that most hurricanes
didn’t have enough supercooled water and that unseeded hurricanes changed in the same
way a seeded one was expected to, pretty much making the project redundant.
In the 1959’s, nuking hurricanes into submission was seriously considered. The idea was that
if you exploded a high yield weapon above the eye, the huge uplift of air seen in the
fireball would suck in cool air and disrupt the storms convention currents.
But there are some serious drawbacks with this, the most obvious being it would spread
highly radioactive isotopes through the wind and rain over a wide area. The second issue
is that hurricanes are heat engines, they get their energy from the warm moist air above
the ocean so adding more heat from the blast would probably make it stronger rather than
weaker. The third problem is the sheer amount of energy
already being released a hurricane which is in a typical one is the equivalent to a 10
megaton weapon being detonated every 20 minutes, so a succession of bombs would be needed to
have the required have any effect. As hurricanes are just air and water vapor the blast shock
wave would have little effect on it’s structure and what water vapor that might be superheated
from the initial X-Ray bust would condense back again a short time after adding more
heat in the process. So if you can’t stop them when they are
large, maybe you could stall them when they are developing and just storms at sea. For
a hurricane to develop the sea temperature must be above 26.5C. Around 80 tropical depressions
form in an average year in the Atlantic but only about 5 to 10 will become hurricanes,
so which ones do you go for. Instead of trying to figure out which might
become a hurricane why not affect them all. There have been several ideas to cool the
ocean surface in the area where they develop using wave-powered pumps, also known as ocean
plowing to either move warm surface water downwards or cool deep water upwards. The
issue here is that you would need thousands of them covering a vast area and in small
scale tests many of these pumps were damaged by the waves.
Another idea which is used in Norway to stop the buildup of ice in fjords is to pump air
into the deep water. As the air bubbles rise to the surface, they bring up the deeper salty
water which stops the ice from forming. If this was done in the warm ocean waters it
could bring up the deeper cooler water to cool the surface depriving the storms of the
heat energy to grow into hurricanes. Again the same issue applies in that you would
need thousands of these solar-powered pumping plants covering a large area to have any effect.
Yet another idea is to make the clouds themselves more reflective by spraying seawater into
them. This would reflect more of the sun’s energy back into space and cooling the sea
below. This has been suggested to help combat global warming and if this was done around
the equator not only would it reduce the amount of available energy for storms to form but
also it would help cool the poles as there the whole point of the atmospheric and ocean
currents is to distribute the heat imbalance form the equator to the poles.
However, there is also the law of unintended consequences on the sea life and the new weather
patterns that would become established if we were artificially cool large areas of the
oceans. Tornados are the other deadly storms but these
are quite different from hurricanes, for one they are much smaller with an average width
of 0.8 km and give very little notice when the form, the funnel clouds lasting from a
few minutes to a couple of hours but in that time they can do tremendous amounts of damage
to anything they encounter. Unlike hurricanes, Tornados nearly always
form overland from large rotating thunderstorms or supercells. These and require cold dry
air over warm humid air and an unstable atmosphere, something which happens regularly over the
great planes of the central US in an area called tornado alley.
Because they form in a different way to hurricanes, primarily due to the difference between the
cool dry air and the warm moist air masses and the lateral winds which provide the spin
to get them going there have been several theories as to how they might be controlled.
One was from the physicist Bernard Eastlund, who if you have seen the video we did on HAARP
was the man behind the idea of the giant ionospheric heater in Alaska that could create heat the
ionosphere to create a lens to focus the suns energy on to an area may be hundreds of kilometers
away. Well the Thunderstorm Solar Power Satellite
which he called it, would be a giant solar collector that would generate electricity
and convert that into microwaves which would be focused on to thunderstorms to heat the
cool rainy downdrafts and disrupting the convection currents within the storm cell.
This might sound far fetched but if you also watched our previous video about spacebased
electrical power generation then you’ll know they are already trailing the microwave
power link technology and the satellite-based solar generators, so it might not be far fetched
for long. But there are problems with this, firstly
the solar power station and microwave transmitter would need to be in geostationary orbit to
stay above the area and to have a 24 hour supply of sunlight for its power. But that
would place them over the equator rather than the central US. At 36,000km away the beam
would be very wide at up to 10km across and not focused enough to pick out the small area
of the cool air in rear flank downdraft of thunderstorms were most tornados start, if
you heat up the already warm air it might just make any tornados stronger.
If the satellite was in a low earth orbit at 400Km, then the beam could be a lot tighter
and stronger but it would be traveling around the earth once every 90 minutes with only
a few minutes over a potential target. Getting the satellite to be over a storm at the right
time and in daylight for its power would be down to luck rather than planning. You would
also have to avoid the high energy microwave from hitting people and livestock on the ground
so it would have to be turned off when over towns and villages.
A variation on this is a ground-based system with high power microwave transmitters mounted
on trucks with large generators. This gets around the problem of being close enough but
you would still need many megawatts of power so a convoy of transmitters and generators
would have to track down the storms just like storm chasers do now. They would then need
to stop and set up in just a few minutes to be effective all whilst avoiding any emerging
tornados. In the real world, this would just not be
practical with current power technology and transportation. So our best hope is better
detection and prediction of where tornados may form and maybe more underground buildings
and structures that would not be affected.
Accurate weather prediction has come a long way in the last 20 years or so using a whole
variety of methods from realtime updating of data in the field to predictive modeling
on supercomputers but all of this requires skills in ways of thinking like a scientist.
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