Hydrosphere - Types, Importance

3847 Words Oct 23rd, 2010 16 Pages
Hydrosphere
The movement of water around, over, and through the Earth is called the water cycle, a key process of the hydrosphere.
In physical geography, the term hydrosphere (Greek hydro means "water") describes the collective mass of water found on, under, and over a planet's surface. The Earth's hydrosphere consists chiefly of the oceans, but technically includes clouds, inland seas, lakes, rivers, and underground waters.
Hydrosphere refers to that portion of Earth that is composed of water. The hydrosphere represents one component of Earth's system, operating in conjunction with the solid crust (lithosphere) and the air that envelopes the planet (atmosphere). The derivation of the term hydrosphere, from the Greek words for water and
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Much of the water on the surface today is thought to have originated from the outer parts of the solar system, such as from objects that arrived from beyond Neptune.
Ice ages
During the history of Earth, there have been a series of periods in which a significant portion of the hydrosphere was locked up in the form of glacial ice. It has even been hypothesized that during the Cryogenian period, this sea ice extended all the way to the equator (see Snowball Earth).
It is currently believed that four major ice ages have taken place during our planet's history. The current ice age began about 4 × 107 years ago, and gained in intensity during the Pleistocene. The most recent withdrawal of ice sheets occurred only 10,000 years ago.
Life
All currently recognized forms of life rely on an active hydrosphere. All organic chemistry indicative of life occurs with water as its solvent. The water cycle in the Earth's hydrosphere allows for the purification of salt water into freshwater. The action of both evaporation and wetland swamps serves to remove a large portion of atmospheric pollutants from the atmosphere (i.e. acid rain). Through this process, the water cycle purifies the gaseous atmosphere. Although most life on the planet exists in the saltwater oceans, humans are particularly interested in the hydrosphere because it provides the fresh water we depend upon.
The search for life on other celestial bodies
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