.ON APRIL 2ND a gizmo being similar to a snowfall maker on the deck of the USS Hornet, a nonexistent aircraft-carrier anchored in San Francisco Gulf, started creating a mist of salty aerosol particles. The medical collaboration behind the venture, the Marine Cloud Whitening (MCB) program, led by the College of Washington, is checking out whether such aerosols could assist to decrease weather modification through a form of “geoengineering”. What does this condition method– as well as why is it therefore controversial?