How surface currents differ from deep ocean currents Objectives: Define current How surface currents differ from deep ocean currents Define Upwelling

Ocean Currents Currents are movements of water through the ocean, almost like rivers in the ocean. Can be large or small, long or short. Caused by wind & differences in water density.

Surface Currents Caused mainly by WIND. The temperature of current depends on where the water originates. Since all oceans are connected, these currents form a continuous worldwide pattern of water circulation.

Surface Currents Some surface currents move in a circular pattern – these currents are called gyres. Gyres in the Northern Hemisphere move CLOCKWISE & in the Southern Hemisphere they move COUNTER-CLOCKWISE This is due to the direction of wind in each hemisphere.

Longshore Currents A type of surface current is the longshore current. Found near the shoreline where waves hit the shore at an angle called wave refraction. When the waves hit shore at an angle, the water changes direction and produces currents that move parallel to the shoreline.

Longshore Currents Longshore currents move sand and sediment in the direction it is moving.

Longshore Currents The sand deposited forms a sandbar. The longshore currents can get trapped on the shoreside of the sandbar until an opening is formed in the sandbar. The currents then return to the ocean & a powerful narrow flow called a rip current is formed.

Deep Ocean Currents Caused mainly by water density differences. Density is affected by temperature and salinity. Cold water is sinks and warm water rushes in to churn it.

Rip Currents aka “rip tides“ and “undertow“ = false! Formed from an opening in the sandbar that the water can travel back to the open ocean. Current pulls it back to the open sea.

Rip Currents Flows perpendicular (T) to the shoreline. If caught in one, swim parallel(ll) to the shore. This could save your life!!!

Deep Ocean Currents Deep ocean currents for a worldwide conveyor belt of currents called thermohaline. (thermo: temp. haline: salinity) These currents move much slower than surface currents.                                                                                                                                                                

Upwelling Deep cold, ocean currents cause upwelling when they reach land. These waters are rich in nutrients since the current traveled along the ocean bottom. Places with upwelling are great places for fishing!!