PressureLearning Objective: | Identify the function and properties of seawater that control pressure, and the unit used to measure pressure. |
Pressure beneath (al di sotto di) the sea surface is measured in decibars. The pressure exerted by 1 meter of seawater very nearly equals 1 decibar (1/10 of a bar) or 100,000 dynes per square centimeter.The farther one descends in the sea, the greater the pressure, and since pressure in the ocean is essentially a function of depth, the numerical value of pressure in decibars approximates the ocean depth in meters. Therefore, pressure ranges from zero at the surface to over 10,000 decibars in the deepest parts of the oceans. The pressure is created by the weight of the seawater above. The weight per unit volume of seawater, in turn, varies with the temperature and salinity.In a column of water of constant depth, the pressure increases as the temperature of the sea decreases, or the salinity increases, or both.
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