Transcript Scales of importance from global to micro Temporal Scales vary.

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
• 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-
Universal Solvent
“Salinity”
• 3.5% of seawater is dissolved substances
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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
coherence of water of similar
temperature
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