Download - Ocean currents:
OCEAN CURRENTS:
CURRENT: Continuous and directed movement of ocean water
TWO TYPES: Surface Currents Deep Water Currents
SURFACE CURRENTS: 10% of water in ocean The upper 400m of the ocean
DEEP WATER CURRENTS: 90% of water in ocean Waters move around the ocean basins by density differences
Density differences a function of different temperatures and salinity
TWO TYPES OF FORCES: Primary Forces: Start the water moving: Solar Heating Winds Gravity Coriolis Effect
Secondary Forces: Influence where the current goes
SOLAR HEATING: Causes water to expand Water is about 8 cm higher than middle latitudes, thus water wants to flow down slope
WINDS: Winds blowing on surface of the ocean push the water
Water piles up in the direction the wind is blowing
GRAVITY Will pull water “down the hill” when water mounds up
CORIOLIS EFFECT: An inertial effect due to the spinning of the earth
When going towards pole you are coming from an area that is moving faster, thus the deflection with the direction of the Earth’s rotationWhen going to the equator, the deflection goes against the spin of the Earth, due to the spin of the Earth
GYRES: The effect of winds and Coriolis effect results in circular flows of water made of several currents
EKMAN TRANSPORT: Surface water is
blown away by winds, dragging the water beneath it
The deflection due to Coriolis Effect creates a spiral pattern and a net current to the right or left of wind
Results in upwelling
UPWELLING: Nutrient rich water from the deeper parts of the ocean rises to the surface to replace the water blown away
Animation:
DEEP WATER CIRCULATION: Occur where the temperature is cold and relatively high in salinity
Thermohaline Circulation Thermo = heat, haline = salt
EARTH CONVEYOR BELT Salt rich, warm water is blown north by the Gulf Stream, where is cools and sinks
This provides heat to the polar regions and nutrients everywhere
Possibly disrupted by global warming
LOCAL CURRENTS: formed by a combination of tides, winds, waves, and rivers/streams
Longshore currents and rip currents
LONGSHORE CURRENTS: When waves strike the shoreline at an oblique angle, causing resultant waves to move parallel with the shoreline
RIP CURRENTS: Formed when waves push the water in front of it sideways till it can find a path out to sea