The
oceans make up about 70% of Earth’s surface
·
Was
formed by volcanic explosions of water vapor
o Water vapor in the
atmosphere cooled and formed droplets of water
o Water fell as rain and made
rivers which then formed the oceans
Chemical
Properties of Ocean Water
·
Ocean
water is a mixture of dissolved gasses, salts, and tiny amounts of many
elements
o Chlorine was from volcanoes,
sodium from weathering
§
Sodium
+ Chlorine = Salt
·
Salinity: number of grams of salts in 1 kg of water
o Average salinity is 34.5
g/kg
o Varies due to rainfall,
water temperature, rivers entering the ocean
o Many different salts in
ocean- see table 15.1 on pg 340
·
Temperature
o Only top of water column is
warmed by the sun
o Surface currents mix warmed
water and move it down to a depth of 100-400 m
o Thermocline: a zone of rapid
temperature change below the surface zone
§
Forms
because water from warm surface floats on top of colder water
§
Depth
of thermocline varies with location and season
·
Density
o ________________________________________________
o ________________________________________________
o Salinity and temperature
affect density
§
______________________________________________________________________________________
§
cold
water is denser than warm water
·
Pressure
o Pressure increases as you go downward towards center of Earth