Oceans cover most (~70%) of Earth’s surface, thus, Earth is sometimes called the ‘water planet’. Oceans affect all our lives by providing food, allowing transport of goods, and affecting weather and climate.
Can We Help with Your Assignment?
Let us do your homework! Professional writers in all subject areas are available and will meet your assignment deadline. Free proofreading and copy-editing included.
Oceanography: the scientific study of the ocean and seas
Properties of Water
-Solid water (ice) is actually less dense than liquid water. Thus, ice floats on water!
WHY? When water freezes, the molecules actually spread out in a rigid framework, creating more void space!
-Water molecules are also held together by strong hydrogen bonds! This makes water very stable and less likely to change forms over a wide range of temperatures!
-Thus, water remains a liquid from 0°C to 100°C!
Properties of Ocean Water
-a measure of the dissolved salts in water
-expressed in parts per thousand (/00)
*35g/1000g seawater = 35/00
-important in identifying water masses
–water mass: a body of water with distinct properties based on where it originates
-raises the boiling point and lowers the freezing point of seawater!
-Seawater remains a liquid from -2°C to 100.3°C
-85% of ocean’s salt is NaCl; table salt!
-Seawater contains over 70 other elements
A. Variations in Salinity
*Water masses in different parts of the world have different salinities based on local conditions.
-Extremely HOT/ DRY climates
- Above average salinity
- Oceans lose water rapidly through evaporation, leaving salts behind
- Ex- Mediterranean and Red Seas
-Extremely COLD climates
- Above average salinity
- Seawater freezes, leaving salts behind
- Ex- Polar waters
-Areas w/large amounts of freshwater
- Below average salinity
- Rivers and glaciers drain into ocean
- Lots of rainfall in/near ocean
- Ex- Baltic Sea and near Equator
-Salt composition has not changed much in the past 200 million years
- Enter = volcanic vents; erosion of land (minerals runoff); organisms decay
- Exit = plants and animals uptake; settle onto the ocean bottom
-Almost all of the energy that heats the oceans comes from the sun.
-Most sunlight is absorbed in the 1st few meters of ocean water.
-Ocean temperature decreases rapidly with depth.
-Ocean is divided into 3 layers:
A. The Surface
-Warmed by sunlight
-Also called the mixed layer because wind and waves mix the heat evenly
-Only about 2% of the ocean’s volume
-From 0 to 300 meters deep
-Very important to life!
–Phytoplankton live here, and make up the base of the ocean’s food chain!
B. The Middle Zone
-Receives only some sunlight
-Also called the thermocline because temperature changes rapidly here
-From 300 to 1000 meters deep
-Bottom of this layer is very cold (5°C)
C. Deep Water
-Receives little to no sunlight
-Water is very cold (2°C) and fairly constant all over the globe
-A few species do manage to live here!