Composition & Characteristics of Oceans

Earth’s oceans are all connected, however, scientists separate the ocean into five main oceans: Pacific Ocean – largest and deepest of the oceans; larger than all of Earth’s continental land mass put together Atlantic Ocean – half the size of the Pacific, covers about 20% of Earth’s surface Indian Ocean – the third largest ocean that is located between India, Africa and the Indonesian Islands Southern Ocean – surrounds the Antarctic continent and is covered by ice part of the year Arctic Ocean – smallest and shallowest ocean that is located near the North Pole and is also covered by ice part of the year

seawater – water from a sea or ocean that has an average salinity of 35 ppt (parts per thousand), or one kg of ocean water contains about 35 g of salt   salinity – measure of the mass of dissolved solids in a mass of water

Oceans are divided into zones based on physical characteristics that include sunlight, temperature, salinity and density

Surface zone – area of shallow seawater that receives the most sunlight; organisms that perform photosynthesis are located here Middle zone – receives very little sunlight and of it only the blue-green wavelengths Deep zone – plants that photosynthesize are not found here because there is NO light; many organisms produce light using chemicals in a process called bioluminescence

Temperature – temperature changes from surface to about 1000 m depending if located in polar or tropical regions Salinity – top 500 m of water is saltier in warmer water than polar water since it evaporates faster leaving behind salt at surface Density – ocean water is layered since cold water is denser than warm water and salt water is denser than fresh water

Ocean Waves & Tides

Wave Movement of energy through a body of water usually formed when winds blow across the water’s surface transferring energy

Parts of a Wave crest – highest point of wave trough – lowest point of wave  wavelength – distance from one crest to another, or from one trough to another amplitude – the amount of energy a wave carries (measured from resting point to crest) frequency – number of waves that pass a point in a certain amount of time

Tides Daily rise and fall of Earth’s waters on its coastlines caused by the gravitational interaction of Earth, the Moon and the Sun The gravitational force between the Earth and the Moon produces two bulges on ocean surfaces – one bulge on side of Earth facing the Moon and the other on the side that’s facing away from the Moon – these bulges represent high tides.

Tidal Range The difference in water level between a high tide and a low tide and vary depending on the positions of the Sun and Moon with respect to Earth

Spring Tide The largest tidal range and occurs when Earth, the Moon and the Sun form a straight line Neap Tide The lowest tidal range and occurs when Earth, the Moon and the Sun form a right angle