In Rainmaker, two proselytes are ordered to destroy European Weather Crystals so that the development of the Weather Controller can be delayed. The Weather Crystals are harmless in this co-op mission.
In Regenbogen Challenge, when the green effect is selected, the Weather Crystals will be activated and start shooting cryo beams rapidly at ground and air units and generate shroud similar to the Gap Generator unless its corresponding base is powered down. They are invulnerable until their corresponding Pacific Front base is destroyed.
Behind the scenes
The artwork of this building by MadHQ is a public asset and can be used by other modders. The link can be found here (called Weather Tower).