Without it, everyone would have to provide their own food and shelter.
We were far away from Germany, Italy and Japan. Water seperated the U.S. from the attacking countries so it was harder for them to attack the U.S.
Convection occurs in fluids (so both liquids and gases, as well as rheids) and is the concerted, collective movement of groups or aggregates of molecules within the above through advection or diffusion or both at the same time. Convection can never take place in solids and is only specific to fluids.
