That means building futuristic structures that use wastewater and solar power to produce hydroponic (grown in a nutrient-rich water, without soil) and aeroponic (grown in water-saturated air) crops.

FORBES: Skyscraper Farms: A Name To Know In 2011

These are boxes containing air that is super-saturated with water vapour.

ECONOMIST: Global warming

Without such particles, clouds would be rare: the air would need to be freakishly saturated with water vapour or strangely cold for condensation to occur.

ECONOMIST: Aerobiology