Most water evaporates from the oceans, which supply about 86–88 % of global evaporation. Land surfaces, including plants, soils, and inland waters, contribute the remaining 12–14 %.
Global water distribution
Only about 71 % of Earth’s surface is water, but 96.5 % of that water is in the oceans. The rest is locked in ice, groundwater, lakes, or the atmosphere. Because the ocean holds the vast majority of liquid water, it naturally dominates evaporation.
Why oceans dominate evaporation
Oceans offer an essentially infinite source of moisture, a large surface area, and a high heat capacity that absorbs solar energy without large temperature swings. These factors keep surface temperatures stable and supply continuous vapor.
Evaporation mechanics
Evaporation requires latent heat to break hydrogen bonds between water molecules. Solar radiation provides this energy; photons raise molecular motion until molecules escape into the air as vapor. The process cools the surface and stores heat in the atmosphere until condensation.
Land evaporation limits
On land, evaporation depends on soil moisture, vegetation, and local weather. Drought, aridity, or closed stomata reduce moisture availability, limiting the amount of water that can evaporate. Even during hot periods, land surfaces cannot match ocean evaporation rates.
Latitudinal evaporation patterns
Evaporation peaks in subtropical ocean belts (10°–30° latitude) where intense solar radiation, steady trade winds, and dry air create high vapor‑pressure deficits. The equator and polar regions have lower rates due to cloud cover and colder temperatures, respectively.
Implications for the hydrological cycle
Because ocean evaporation feeds most of the atmospheric moisture, it drives cloud formation, precipitation patterns, and ultimately the global water cycle. Understanding this source helps predict weather and climate change impacts.