Ocean Composition How many oceans are there There
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Ocean Composition
How many oceans are there? • There is only one global ocean. • Covers 71% of Earth • Divided into 4 regions (5 according to the United States) – – – Atlantic Pacific Indian Arctic *Southern (Antarctic) • All 5 regions are connected.
Ocean or Sea? What’s the difference? • Seas are smaller than oceans and are usually located where the land ocean meet. Typically, seas are partially enclosed by land.
Salinity • Salinity – a measure of the amount of dissolved solids in a given amount of liquid –Measured as grams of dissolved solids per kilogram of water • 1 kg of ocean water contains 35 g of dissolved solids
Where does all that salt come from? • Runoff (Erosion) – Acid rain breaks down rocks dissolved salts and minerals are carried away (runoff) rain and dissolved salts and minerals are deposited in the ocean
What affects salinity? • Climate –Coastal water in places with hotter, drier climates has a higher salinity –Coastal water in cooler, more humid places has a lower salinity 1. More fresh water from streams and rivers run into the ocean in these areas 2. Glaciers melting add freshwater to the oceans –Heat INCREASES the evaporation rate. Evaporation removes water but leaves salts and other dissolved solids behind.
• Water Movement – Slower moving areas of water develop higher salinity • Example: bays, gulfs, seas, open ocean without currents running through them Dead Sea = Very Salty – 337 PPT (33. 7%) Baltic Sea = Not Very Salty – 10 PPT (1%)
Changes in Temperature • Tropical Regions – As depth increases, water cools rapidly. That is because there is less sunlight to warm water as depth increases. • Polar Regions – The temperature remains fairly constant. This is because sunlight intensity at Earth’s poles is weaker than it is in other regions.
Changes in Salinity • The top 500 meters of warm water in tropical regions is saltier than polar regions. • Warm water evaporates more rapidly than cold water. • In polar regions, freshwater from melting glaciers decreases the salinity at the surface. • When ice forms, salt is left behind in the water. – cold, salty water is denser and sinks to a deeper layer
Changes in Density • Ocean water is layered due to different densities. • Cold water is denser than warm water. • Salt water is denser than freshwater.