Chapter 13 Oceans
13.1 Ocean Currents What is the difference between a current and a wave? Waves are on the surface of water (i.e. - ocean waves at a beach) Currents are below the surface (i.e. – EAC – East Australian Current)
13.1 Ocean Currents surface currents – currents near the surface of the ocean (warm and/or cold currents) 3 things can change the direction of surface currents: continental deflections – currents change direction because they hit a continent global winds – global winds can blow a current a different direction Coriolis effect – the Earth rotating changes the direction of winds and currents (they do not go straight because the Earth is turning in circles) (i.e. – throwing a ball onto a spinning merry-go-round)
13.1 Ocean Currents deep currents – currents far below the surface of the ocean (all cold currents) Deep currents travel along the ocean floor
13.2 Ocean Waves El Niño – a change in the water temperature in the Pacific Ocean that produces a warm current (more severe) La Niña – a change in the eastern Pacific Ocean in which the surface water temperature becomes unusually cool
13.2 Ocean Waves upwelling – happens near the shore where cold water rises to replace the warm water that has been blown out to sea by wind Upwelling helped to cause the El Niño phenomenon
13.3 Ocean Waves crest – highest point of a wave trough – lowest point of a wave wave length – the distance between two wave crests or two wave troughs wave height – the distance between the wave crest and the wave trough wave period – the time it takes for two waves to pass over a fixed point
13.3 Ocean Waves breaker zone – the near-shore area where waves are at their highest point right as they begin to break or tumble downward Surfers surf on the breaker zone surf – the near-shore area where waves have broken and the water is calmer white caps – white foaming waves with steep crests that break in the open ocean Heavy winds or storms can cause white caps swells – steady waves out in the open ocean
13.3 Ocean Waves tsunamis – large waves that form in the ocean due to an underwater earthquake, volcanic eruptions, landslides, underwater explosions, or a meteorite hitting the ocean storm surge – a rise in sea level near the shore that was caused by strong winds, hurricanes, or a tsunami
13.3 Tides high tide – when the water level rises near the shore low tide – when the water level lowers near the shore