Unit 5 Fresh and Saltwater Systems Topic 4 The Oceans Read: Pages 410 - 429 Remember to name and date your notes!

The ocean is always moving. Ocean’s affect weather Ocean’s provide food, oils, gases, and minerals. We transport across oceans. Oceans cover over 66% of the planet.

Ocean water is salty! 1000g of seawater contains 35g of salt – on average. 35 PPT – Parts Per Thousand Salinity: measure of the amount of salts dissolved in a liquid.

Salts in the ocean come from rivers and groundwater flowing over rocks, picking up salts, and carrying them to the ocean. When volcanoes release lava and gas on the sea floor, sulfur and chlorine are added to water.

What’s On the Ocean Floor? Large mountain ranges, deep valleys, vast plains. These features are a result of tectonic plates, not wind, rain, and rivers as we see on earth.

Ocean ridges: youngest part of ocean floor and are formed by eruptions. Lava flows from these ridges and quickly hardens. Can be 1000km wide and 1000-3000 m high.

Trenches: formed where an ocean plate meets a continental plate Trenches: formed where an ocean plate meets a continental plate. The ocean plate is forced below.

Abyssal Plains: wide, open plains between mountains and trenches. Continental Shelf: slope gradually away from the land before dropping steeply downward at the shelf edge.

Continental Slope: from the edge of the shelf, the slope plunges at a steep angle to the ocean floor.

Ocean Waves Just large ripples, set in motion by steady winds. Smooth waves are called swells.

Parts of Waves Crest: highest part Trough: lowest part Wavelength: distance from one crest to the next. Speed of motion: time for one wave to pass a given point.

Breaker: wave collapses on shore in a tumble of water Breaker: wave collapses on shore in a tumble of water. Happens because the trough of the wave hits the beach, slows due to friction, but the crest carries on at it’s normal speed.

Waves shape shorelines by eroding and redepositing sediments. Waves slowly wear away rocks and cliffs…sea arches sometime result.

How are Beaches Formed? Rock fragments carried in waves rub together and break down. On a steep shoreline, these fragments roll back into the sea. On a gradual shoreline, they rest and beaches form.

Tides Tides are the slow rise and fall of the ocean in daily cycles. Spring tides, the largest, occur when the Earth, moon and sun are aligned.

The difference in level between a high and low tide is called the tidal range. Tidal movements result mainly from the pull of the moon’s gravity on the ocean. High tide on one beach means low on the other side.

Ocean Currents Broad continuous movements of ocean water are called currents. Like a massive river in the ocean.

Surface Currents Currents at the ocean surface driven by winds. (Top 100 – 200 m) Three factors influence the direction of winds and surface and currents:

1) Uneven heating of atmosphere. Warm air expands upward and outward 1) Uneven heating of atmosphere. Warm air expands upward and outward. This creates an area of low pressure. Cool air has a high pressure and moves the low pressure air…this movement creates wind.

2) Rotation of the Earth: trade winds at the equator push ocean currents to the west. At the polar regions, westerly winds drive currents east.

3) Continents: continents deflect east-west currents either north of south.

Ocean Temp. and Currents Winds and currents mix heat evenly through surface waters. Sun’s rays cannot penetrate, so temp. drops quickly past 200m. Think of mixing bath water to warm it up.

Gulf Steam: starts in the Caribbean Sea and flows north along the east coast of North America. Then turns northeast and crosses the Atlantic. Carries warm water to Iceland and British Isles.

Warm currents transfer their heat to the atmosphere. Water has a high heat capacity – takes a long time to heat up and cool down. Large bodies act as heat reservoirs in winter, staying warmer than nearby land.

The difference in temp. between the water and land affects the weather systems near the shoreline….produce breezes and these breezes affect evaporation and condensation also.