Hydrosphere
The hydrosphere is all water on Earth, including liquid water, ice, and water vapor. It spans the oceans, land, atmosphere, and living things.
Ocean: A vast body of saline water covering much of Earth’s surface. The oceans hold most of Earth’s water.
Evaporation: The change of a liquid into vapor from its surface. It moves liquid water from oceans and land into the atmosphere.
Freshwater: Water with low concentrations of dissolved salts, found in rivers, lakes, groundwater, and ice. It is the limited portion of Earth’s water most directly available for many human uses.
Sea-level rise: A long-term increase in the average level of the global ocean. Warming expands seawater and melting land ice adds water to the oceans.
Groundwater: Water stored beneath Earth’s surface in soil and permeable rock. It is a major reservoir of liquid water hidden below land.
Condensation: The change of a gas into a liquid, often forming droplets when air cools. It turns atmospheric water vapor into cloud droplets.
Water resource: Water available for human use, including supplies for drinking, agriculture, industry, and ecosystems. It frames the hydrosphere in terms of usable supply and demand.
Thermohaline circulation: Large-scale ocean circulation driven by differences in seawater density related to temperature and salinity. It transports heat through the ocean and influences regional climates.
Glacier: A persistent mass of ice formed from accumulated and compacted snow that moves under its own weight. Glaciers and ice sheets store a substantial share of Earth’s freshwater.
Precipitation: Water released from clouds as rain, snow, sleet, or hail. It returns atmospheric water to Earth’s surface.