What kind of scientific research and difficulties have scientists encountered in accurately forecasting or changing the weather?

Scientists have been trying to study the movement of molecules, atoms and initial smoke-like particles for a long time, and how these particles combine to form condensation. When the aggregate of these particles develops into a cloud drop, at least 1 million such cloud drops must be combined to form a raindrop, and whether it will become a raindrop depends on the electrical, chemical and aerodynamic characteristics of the surface of the cloud drop, as well as its number and density. In order to accurately forecast the weather or change the weather, we must first understand these microphysical processes. Many of these processes have been studied in the ground slaughter and inspection room and achieved a lot of results. But the biggest problem is how to overcome the technical difficulties of gravity effect.