Seeding is easy. Clouds are hard

Obviously we could create heat blah blah on earth through volcanoes or whatever.  Never going to be efficient unless someone has seen something I haven't.  I keep going back to space.  Risky sending a beam of radiation to the ocean, but I am sure the tests have been done to the atmospheric implications.  Even if we rip a hole in the ozone, we could repair it.  we are pretty good at making atmosphere as a species.  (CO2)

1) A mirror system- not ant frying power, but warming over an area of ocean on the upwind side sounds about perfect.    The main ramification being: The water that is now warmed and moving to another portion of the ocean can do damage to ecosystems.  To avoid this, make pools.  Then the water at most just drys up until we add more water.  If it turns into a lava pit on accident no harm no foul if overcooked.  We have volcanoes all over, some magma earth might just make a bunch of rare metals form but going down 6-30 miles isnt going to happen- it would be surface damage.  fill it with water again, and cover the burn mark :).  A lake 1/10th the size of lake erie would be plenty to form a massive cloud sprawl. 

We can either take power from earth, by having the mirror redirect light already destined for the planet, or, we could take light not bound for the planet and direct the radiation from there.  depending on what the planet needs, we kind of create a thermostat with that implementation.  The lagrange point between earth and the moon is too far, maybe.  If we are nasty in that capability, then a targeted beam could work but even light takes a while to get from the moon to earth so the chance of missing is higher than a mirror in LEO.  we could have the mirror spin around the planet at a high rate to keep it in orbit, but then you have a pulse system to hit the lake and that creates more complexity.  Therefore, we need fuel to keep the rotation slower which will require more fuel to push outward.

2) Chemical reaction.  There are many reactions that end in water.  A lake made of such chemicals to spawn a high evaporation rate could be an example, this does not have to be a direct process.  Then you need less power from space if a hybird model with part 1.

3) If we can't do space.  I like volcanoes, and grabbing a bit of a jetstream and redirecting it.  you could increase the rate of energy in the jetstream to replace the stolen current for other ecosystems.  messy due to difficulty gathering exact measurements across a vast area, so we will have too much or too little and it will mess with ecosystems, how much is the question.  Hurricane sandy re wrote the entire eastern seaboard so I cannot say we shouldnt take the risk, the planet changes constantly much more severely on a regular basis, not including outside impacts, like objects, asteroids.

4) canopy.  If we ignore weather modification alltogether, and go with a desalination plan and water the desert, it also would create clouds from our watering efforts and the plants giving off moisture.  they would also retain water much more than sand obviously.  Perhaps a large planting effort should be tested.  I am just afraid the energy to run that process would be so costly to the planet we would do more harm than good.  even a small net effect is not worth the risk.  beam me up scotty,

5) One problem is the heat in the Desert for plants.  Having a mirror system in the area we are trying to grow in could provide shade, to keep the earth cooler, thus causing less evaporation of the rain we do cause.  The problem I see, is that we may need to cook the water overnight too to get a good effect and not blasting the planet all at once, spread the energy delivery over time.  If the mirrors on the ground are on the upwind side, they will not be covered by the ensuing clouds, whereas all the mirrors downwind will be blocked if it starts working.   Several ground mirrors 2 step reflecting to the water is a way to gather the light, rather than layering the mirrors higher and higher to shoot the water fyi.  we can focus the beam that way too, however that is more dangerous.  a normal mirror reflecting, people can walk by and get tan rather than being cooked.