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Temperature & Salinity. Solar radiation is absorbed by seawater and stored as heat in the oceans . - evaporates seawater - incr. temp. & incr. salinity ( heating - expands molecules - decr . density ; cools - contracts - incr. density )
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Solar radiation is absorbed by seawater and stored as heat in the oceans. • -evaporates seawater • -incr. temp. & incr. salinity • (heating - expands molecules - decr. density ; • cools - contracts - incr. density) • (higher salinity is denser than lower salinity ) • (incr. press. - incr. density; slight pressure differences in top 1000m. but incr. with depth.) • changes in density can cause water to move
Temperature changes have greatest influence on water density • -temp. variations are greater 2°C - 35°C vs. salinity of 33 0/00 - 37 0/00 • Thermocline - water layer where temp. decr. rapidly with depth. • -density barrier to vertical circulation except in polar areas because surface is colder and has mixing.
Surface Temperatures • -isotherms are lines that connect pts. of equal temperature • -major circulation patterns are from equator to poles on west sides of oceans and pole to equator on east sides of oceans • Pacific Ocean Atlantic Ocean • NA • CA current Gulf Stream
the oceans’ heat absorption ability keeps coastal climates cooler in summer and the re-radiation of stored heat from ocean causes coastal areas to stay warmer than inland areas of same latitude in winter.
Upwelling is the rising of cold nutrient rich water up from the deep replacing the warm surface water. *Diverging boundaries • -caused by wind & coriolus effect (deflects to the right in N. Hemisphere) • -downwelling sinking of cold dense surface water. *Converging boundaries
Salinity - remains constant for the ocean as a whole but varies from place to place. • -salt comes from weathering and dissolution of minerals on land & volc. Emissions • -average salinity 34.73 parts salt / 1000 parts water • 34.73 0/00 (33.0 0/00 - 37.0 0/00)
-evaporation, precipitation & mixing effect salinity amount • (high salinity - coastal with runoff & high evap. with little mixing; • ex: Red Sea & Mediterranean Sea; subtropics & middle latitude • low salinity @ equator due to rainfall) • isohalines - line connecting pts. of equal salinity
Physical properties • -fresh water freezes at 0°C - salt decr. freezing pt. by almost 2°C • (polar regions - salt is expelled from ice as it forms and freezing temp. is decr.) • -dissolved constituents are in constant ratios to each other. • (chloride 55%, sodium 31% by weight)