Osmosis (Revisited) Video Density mass per volume of seawater Determined by temperature and salinity Density of seawater increases all the way to its freezing point of -1.9 C Pressure Light Oceanic Circulation Surface Wind Driven currents, waves and tides Deep Sea Currents Thermohaline Circulation (Oceanic Conveyor Belt) Waves Tides Atmospheric Circulation Atmospheric conditions lead to the development of winds Less dense air rises causing a low pressure Heavier air sinks causing a high pressure Atmospheric Circulation Coriolis Effect Earths rotation changes speed depending on the latitude Greatest at the equator (1674 km/hr) Smallest at poles (0 km/hr) N. Hemisphere Deflects motion to right S. Hemisphere Deflects motion to left Coriolis Effect Salinity Temperature Surface Currents: Wind Driven Wind imparts energy Speed Fetch (distance over which wind blows) Duration Coriolis force deflects currents Northern Hemisphere: deflection to right Southern Hemisphere: deflection to left Geography affects currents Beaufort Wind Force Scale (NOAA) Force 0 Force 2 Force 7Force 11 Surface Currents: Wind Driven Wind imparts energy Speed Fetch (distance over which wind blows) Duration Coriolis force deflects currents Northern Hemisphere: deflection to right Southern Hemisphere: deflection to left Geography affects currents Beaufort Wind Force Scale (NOAA) Force 0 Force 2 Force 7Force 11 Winds and the Resulting Ocean Flow Ekman Spiral Major Surface Currents of the Oceans Thermohaline Circulation Deep Currents are density related As water gets colder and more saline it sinks Downwelling Areas: where water sinks Upwelling Areas: where water rises to surface Conditions at surface determine the temperature and salinity of water Density determines the depth to which the water sinks Atlantic Deep Water Formation The Oceanic Conveyor Belt