Could we control the weather with a disk in space? There is recorded evidence from solar eclipses that the moon's shadow has a detectable weather effect.

If we placed a disk in space we could project a cold spot onto the planet and control it's position using the position of the spacecraft. In simple terms warm air moves towards cold, so that could be used to pull weather systems out of their normal track.


What is the smallest disk that would create a 300km shadow


Where would be the best place to put it between the earth and sun

What size of effect would you have?


Could you move a monsoon from flooded Asia to drought Australia
How big would the shadow need to be to have an appreciable effect?

If it was always "on" (i.e. you could turn it "off" by rotating it on edge), would the cooling effect be significant?


It's not going to stop global warming but it might buy some time and help redistribute the water more evenly.
Maybe this question belongs also into the space department here.

The only Lagrange point that makes sense is Earth - Sun - L1, and it is unstable (needs continuous correction). Satellites have already been put there, e.g. SOHO. But what we really need to do is cut down greenhouse gas emissions, anything else is not sustainable, or not practicable (a 300km sail in L1 belongs to the latter). Looking at the problems NASA has with the heat shield of the James Webb telescope i am tempted to say that it is not makeable with current technology.

Geostationary orbit is not an option. The spacing between satellites is much too small and the shield would only cover the equator. Even in geosynchronuous orbits the satellite spacing is down to 73km (https://en.wikipedia.org/wiki/List_of_satellites_in_geosynchronous_orbit) i read, so that's also occupied for such a frond. It'll collide in the ascending/descending nodes with other stuff.

The risks of geo- and climate engineering, e.g. lack of knowledge about possible side effects and the potentially drastical acceleration of global warming when engineering efforts cease (out of money error ;-)) and the time when they were in effect has not been used to cut down greenhouse gas emissions, are huge.