Oil is the anwser because it is man made and natural and humans will need it a lot in the future
For future people, the answer is the Grand coulee Dam
Cold air is dense and warmer air is less dense and so as the cool dense air sinks the warm air rises and takes its place causing a convection current. This is the same with water and other gaseous and liquid substances.
On starry evenings in late summer and early fall in the Shenandoah Valley. The ground haze frame in the low ranges close to the Shenandoah River is cool with dropping air meets damp air in the low regions close to the waterway.
