.ON APRIL 2ND a device appearing like a snowfall machine on the deck of the USS Hornet, a nonexistent aircraft-carrier tied in San Francisco Bay, began creating a moisture of salted spray bits. The medical partnership behind the task, the Marine Cloud Whitening (MCB) program, led due to the University of Washington, is exploring whether such sprays might help to decrease weather adjustment by means of a type of "geoengineering". What does this phrase mean-- as well as why is it therefore disputable?