People need water. Clouds are the cheapest means of
transporting water from the sea to land.
On the rainy days you don't need to interfere.
But then if there has been a long drought (corrected the
spelling from draught thanks zen_tom) here's my
proposal:
All that's needed are a few blimps
and good weather.
The blimps are anchored to the ground (or undersea)
along
the wished path.
In the designated sea area various schemes are used to
create evaporative and condensive conditions for your
cloud to form. Ultrasound vaporisers may be inserted in
the water on floats. A large mylar fresnel lens could be
extended above the area, between your blimps,
anchored
in a circle. Or use other ideas from here on the HB like
an
extended updraft energy tower.
Perhaps even seawater mist can pumped up and sprayed
back way out at sea, so that the salt particles in the air
do
not cause harm.
Various other cooling schemes can be used, the best of
which is to simply blow the air to the correct
atmospheric
layer, where it should then condense.
Anyway, once your cloud is assembled at the desired
hight,
an extremely lightweight (and perhaps partially carried
by
hydrogen/hellium) thin mylar coating should be wrapped
around the cload, and it should then be driven via an RF
Remote Control unit (using X10) to the desired location
over land. This should cost the equivalent of moving a
tanker in the sea, if not less - because you should be
assisting yourself with the correct air streams for
energy,
and perhaps with "sails" at the correct height.
Once the cloud reaches the correct location above your
desired rainfall area (presumably above a national lake
or
mountains where it will help refill the depleting aquifer)
it
is hitched to a zepelin, and by pulling it up or down to a
stream at the right temperature, you can cause it to rain
its water. If there is no cool level in the atmosphere at
this
time, you can always shoot a jet of CO2 or dry ice to
create the effect inside your "cloud" balloon.