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Scales of importance from global to micro. Temporal Scales vary. Global currents. mesoscale. microscale. What do we need to know about the basic characteristics of sea water?. Important phenomena: Dissolves many compounds Heats and cools more slowly than land masses
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What do we need to know about the basic characteristics of sea water? • Important phenomena: • Dissolves many compounds • Heats and cools more slowly than land masses • Remains liquid over a large range of temp’s • Flows in coherent bodies
Mechanisms for characteristics • Polarity of the water molecule • Dissociation to H+ and OH-
“Salinity” • 3.5% of seawater is dissolved substances • Chloride & Sodium (85.65% of d.s.) • Magnesium & Sulfate (11.37% of d.s.) • Calcium & Potassium (2.26 of d.s.) • Other important, but rarer, components • bicarbonate, bromide, boric acid, iron, strontium
“Saline” or “Haline”? • PSU (practical salinity units) • Parts per thousand • 3.5% equals 35 psu – • But accurate measurements use conductivity relative to a standard • Why is ‘salty’ inland water different than seawater?
High Molecular Cohesion High Viscosity, High Surface Tension Consequences to Organisms? consider small scale to large scale
High “Heat capacity” • Combination of slower evaporation at high temperatures, and large amount of heat gained when changing from solid to liquid • Sea water changes temperature slowly
Temperature & salinity affect water density • Highest density of ocean water = -1.9 C • (pure water highest density is 4 C, so ice floats) • Very cold ocean water sinks • promotes circulation between surface and depths • most ocean is open water at surface (important for gas exchange) • Ocean ice floats (why?)
Density + Coherence at small scale = • segregation of water bodies at large scale