.ON APRIL 2ND a gizmo resembling a snowfall equipment on the deck of the USS Hornet, a defunct aircraft-carrier tied in San Francisco Bay, started making a moisture of salted spray fragments. The medical partnership responsible for the job, the Marine Cloud Brightening (MCB) programme, led due to the Educational institution of Washington, is actually looking into whether such sprays may assist to decrease environment change with a type of "geoengineering". What does this term way-- and why is it therefore controversial?