.ON APRIL 2ND a gizmo resembling a snow device on the deck of the USS Hornet, an inoperative aircraft-carrier moored in San Francisco Bay, began generating a haze of salted spray particles. The scientific cooperation behind the job, the Marine Cloud Brightening (MCB) programme, led due to the University of Washington, is exploring whether such aerosols might help to decrease weather modification with a kind of "geoengineering". What performs this phrase way-- as well as why is it so questionable?