An atmospheric lake is a long-lived moisture-rich pool of slow moving water vapor. Currently, such pools are only known to exist over the western equatorial Indian Ocean (WEIO).[1][2][3] Atmospheric lakes are formed when streams of water vapor separate from the South Asian monsoons to become isolated objects. These objects last for days at a time,[3][4] slowly meandering to the coasts.[2] They move slowly as they exist in regions that lack strong winds.[5] Atmospheric lakes can occur several times during the year.[3][4]
Atmospheric lakes move water from one area and to other areas that are dry and semi-arid. Atmospheric lakes that occur away from the equator sometimes become tropical cyclones.[6][5]