My interest in water... What is WATER?
Water covers 71% the Earth's surface; the oceans contain 97.2% of Earth's water. The Antarctic ice sheet, which contains 90% of all fresh water on Earth, is visible at the bottom. Condensed atmospheric water can be seen as clouds, contributing to the earth's albedo.
Water is a common chemical substance that is essential to all known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor. About 1,460 teratonnes (Tt) of water cover 71% of Earth's surface, mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation.
Some of the Earth's water is a part of man-made and natural objects near the earth's surface such as water towers, and animal and plant bodies, manufactured products, and food stores.
Saltwater oceans hold 97.0% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers and lakes 0.6%. Water in these forms moves perpetually through the water cycle of evaporation and transpiration, precipitation, and runoff usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea, about 36 Tt per year.
Over land, evaporation and transpiration contribute another 71 Tt per year to the precipitation of 107 Tt per year over land. Some water is trapped for periods in ice caps, glaciers, aquifers, or in lakes, for varying periods, sometimes providing fresh water for life on land. Clean, fresh water is essential to human and other life.
In many parts of the world, it is in short supply. Many very important chemical substances, such as salts, sugars, acids, alkalis, some gases (especially oxygen), and many organic molecules dissolve in water.
Outside of our planet, a significant quantity is thought to exist underground on the planet Mars, on the moons Europa and Enceladus, and on the exoplanets known as HD 189733 and HD 209458. [source: Wikipedia]
