Oceans: A Brief Intro Dr. Mark A. McGinleyHonors 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
Table 1: Surface area of our planet covered by oceans, water and land. Percent of Earths Area (Square Area (SquareSurface Total Surface Area Kilometers) Miles)Earths Surface Area 29.2% 148,940,000 57,491,000Covered by LandEarths Surface Area 70.8% 361,132,000 139,397,000Covered by WaterEarths Surface Area 65.7% 335,258,000 129,444,000Covered by OceanPacific Ocean 30.5% 155,557,000 60,045,000Atlantic Ocean 15.1% 76,762,000 29,630,000Indian Ocean 13.4% 68,556,000 26,463,000Southern Ocean 4.0% 20,327,000 7,846,000Arctic Ocean 2.8% 14,056,000 5,426,000
Important Properties of WaterWater is unique in that it is the onlynatural substance that is found in allthree physical states- liquid, solid, andgas—at the temperatures normallyfound on Earth. - Hydrologic Cycle http://ga.water.usgs.gov/edu/waterproperties.html
Important Properties of WaterWater is unusual in that the solid form,ice, is less dense than the liquid form.Thus, ice floats.
Important Properties of WaterWater is called the “universal solvent"because it dissolves more substancesthan any other liquid. -wherever water goes, eitherthrough the ground or through ourbodies, it takes along valuablechemicals, minerals, and nutrients. - most important biochemicalreactions take place among chemicalsdissolved in water in cells
Important Properties of WaterWater 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 cars 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.
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 • Minor elements (< 100 ppm) ppm) – Chlorine – Bromine – Sodium – Carbon – Magnesium – Strontium – Sulfur – Borom – Calcium – Silicon – Potassium – Flourine
Structure of the Ocean• The ocean is not just a giant swimming pool!!
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).