Scientists have created a global map showing sources of atmospheric moisture. They found that on average 40 per cent of terrestrial precipitation originate from land evaporation and 57 per cent of all terrestrial evaporation returns as precipitation.

Some regions rely on water recycled from within the region, while others get moisture from different regions. The study suggests that land use changes such as irrigation, dams, and deforestation can alter evaporation patterns in a region, potentially affecting water resources globally.

Source: Down To Earth, December 2010