.ON APRIL 2ND a device resembling a snowfall device on the deck of the USS Hornet, a nonexistent aircraft-carrier anchored in San Francisco Bay, began creating a mist of salted aerosol particles. The clinical collaboration responsible for the project, the Marine Cloud Brightening (MCB) programme, led by the University of Washington, is actually examining whether such sprays might aid to reduce weather improvement by means of a type of “geoengineering”. What performs this condition method– and why is it therefore controversial?