Post on 11-May-2015
Oceans:A Brief IntroDr. Mark A. McGinley
Honors College and Department of Biological Sciences
Texas Tech University
Fun Facts
• 71 % of Earth’s surface covered by oceans– 80 % of Southern Hemisphere– 60 % of Northern Hemisphere
• Ocean average depth- 4,000 meters• Maximum depth 11,000- meters (approx 7
miles) in Marianas Trench• Below 1000 meters the ocean is dark and cold– Largely lifeless
Oceans of the World
Table 1: Surface area of our planet covered by oceans, water and land.
Surface Percent of Earth'sTotal Surface Area
Area (SquareKilometers)
Area (SquareMiles)
Earth's Surface Area Covered by Land
29.2% 148,940,000 57,491,000
Earth's Surface Area Covered by Water
70.8% 361,132,000 139,397,000
Earth's Surface Area Covered by Ocean
65.7% 335,258,000 129,444,000
Pacific Ocean 30.5% 155,557,000 60,045,000
Atlantic Ocean 15.1% 76,762,000 29,630,000
Indian Ocean 13.4% 68,556,000 26,463,000
Southern Ocean 4.0% 20,327,000 7,846,000
Arctic Ocean 2.8% 14,056,000 5,426,000
Pacific Ocean
Important Properties of Water
Water is unique in that it is the only natural substance that is found in all three physical states- liquid, solid, and gas—at the temperatures normally found on Earth.
- Hydrologic Cycle
http://ga.water.usgs.gov/edu/waterproperties.html
Important Properties of Water
Water is unusual in that the solid form, ice, is less dense than the liquid form. Thus, ice floats.
Important Properties of Water
Water is called the “universal solvent" because it dissolves more substances than any other liquid.
-wherever water goes, either through the ground or through our bodies, it takes along valuable chemicals, minerals, and nutrients.
- most important biochemical reactions take place among chemicals dissolved in water in cells
Important Properties of Water
Water molecules are highly cohesive-very sticky. Surface Tension.
Important Properties of Water
• Water has a high specific heat index– it absorbs a lot of heat before it begins to get hot.
• This is why water is valuable to industries and in your car's radiator as a coolant.
• The high specific heat index of water also helps regulate the rate at which air changes temperature– why the temperature change between seasons is
gradual rather than sudden, especially near the oceans.
Patterns of Temperature Variation
33o N 34o N
Important Properties of Water
• The relative high density of water allows sound to move through it long distances – ask a whale!
• In sea water at 30°C, sound has a velocity of 1,545 meters per second (about 3,500 miles per hour).
Water
• Often hear references to “fresh water” and “sea water”
• Fresh water has no, or very low concentration of, substances dissolved in it
• Sea water (sometimes referred to as “salt water) has higher concentration of dissolved substances
Salinity
• Salinity– Measures the amount of dissolved inorganic solids
in seawater• Expressed as parts per thousand (ppt) or percent (%)
Sea Water
• Major elements (> 100 ppm)– Chlorine– Sodium– Magnesium– Sulfur– Calcium– Potassium
• Minor elements (< 100 ppm)– Bromine– Carbon– Strontium– Borom– Silicon– Flourine
Structure of the Ocean
• The ocean is not just a giant swimming pool!!
Cross Section of Ocean Basins
Continental Shelf
Continental Shelf
• The average width of continental shelves is about 80 km (50 mi).
• The depth of the shelf also varies, but is generally limited to water shallower than 150 m (490 ft).
• The slope of the shelf is usually quite low, on the order of 0.5°; vertical relief is also minimal, at less than 20 m (66 ft).
Global Continental Shelf
Importance of DepthLight Penetration
Importance of DepthTemperature
Pelagic Zone
Abyssal Pelagic Zone
Hydrothermal Vents