online viagra reviews
|Upper Mantle||Lithospheric Mantle|
|Deeper Upper Mantle|
|Topics: | | | | | | ||
Hydrosphere ( hydro means "") in , describes the collective mass of water found on, under, and over the surface of a .
online viagra without prescription
The Earth's hydrosphere consists chiefly of oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters. The average depth of the oceans is 3,794 m (12,447 ft), more than five times the average height of the . The mass of the oceans is approximately 1.35 √ó 1018 tonnes, or about 1/4400 of the total mass of the Earth.
The abundance of water on is a feature that distinguishes our "Blue Planet" from others in the solar system. , a satellite of is covered with water ice. There is speculation that there may be liquid water and life below the ice. Approximately 70.8 percent (97% of it being sea water and 3% <ref></ref>) of the Earth is covered by water and only 29.2 percent is landmass. Earth's solar orbit, , , , and oxygen-rich atmosphere seem to combine to make Earth a water planet.
Earth is actually beyond the outer edge of the orbits which would be warm enough to form liquid water. Without some form of a , Earth's water would freeze. evidence indicates that at one point after blue-green bacteria () had colonized the oceans, the greenhouse effect failed, and Earth's oceans may have completely frozen over for 10 to 100 million years in what is called a event.
On other planets, such as Venus, gaseous water is destroyed (cracked) by solar radiation, and the is and blown away by the . This effect is slow, but inexorable. This is one hypothesis explaining why Venus has no water. Without hydrogen, the oxygen interacts with the surface and is bound up in solid .
In the Earth's atmosphere, a tenuous layer of within the stratosphere absorbs most of this energetic ultraviolet radiation high in the atmosphere, reducing the . The ozone, too, can only be produced in an atmosphere with a large amount of free diatomic oxygen, and so also is dependent on the biosphere (). The also shields the from direct scouring by the solar wind.
Finally, vulcanism continuously emits water from the interior. Earth's recycle and water as rocks are into the mantle and volcanically released as gaseous carbon dioxide and . It is estimated that the minerals in the mantle may contain as much as 10 times the water as in all of the current oceans, though most of this trapped water will never be released.
The describes the methods of transport for water in the hydrosphere. This cycle includes water beneath the Earth's surface and in rocks (), the water in plants and animals (), the water covering the surface of the planet in liquid and solid forms, and the water in the in the form of , , and . Movement of water within the hydrosphere is described by the . It is easy to see this motion in and , but it is harder to tell that there is this motion in and .
The characteristics of the that affects its motion are its and . Warm water is lighter or less dense than cold water which is more or heavier and salty water is also more dense than . The combination of the water's temperature and salinity determines whether it rises to the surface, sinks to the bottom, or stays at some intermediate depth.