Vertical temperature change ● Temperature – there are 3 temperature zones in the ocean. ● Surface to 200 meters – warmed by the Sun. ● Thermocline: 200 to 800 meters – sharp drop in temperature ● Deep water: 800 meters and below – almost freezing. ● Cold water is more dense than warm water.

Surface water ● Warmest water is located near the Equator due to direct solar radiation. ● Coldest water is located near the poles due to indirect solar radiation.

Surface Currents ● Are caused by wind. ● Only affect the top 200 meters of the ocean. ● Are affected by the Coriolis Effect which causes the currents to curve. ● Clockwise in the Northern hemisphere. ● Counterclockwise in the Southern hemisphere.

Deep currents ● Are caused by differences in density. ● Move across the ocean floor ● Can take 1000 years to travel from the poles to the Equator

Down welling ● Surface water sinks bringing oxygen to the ocean floor, allowing deep water marine life to exist.

Upwelling ● Wind moves water away from the coast, creating a void. The void pulls cold water up from the deep. ● Brings nutrients up from the ocean floor. ● Many marine creatures. ● Fish nurseries. ● Upwelling on the coast of Chile is vital to the survival of anchovies.

Currents and Climate ● Ocean currents cool or warm the air above them, affecting climate. ● Cities at the same latitude may have very different climates because of the ocean currents near them.

Changing currents ● Creates El nino and La nina – El nino is a warmer than usual current which changes the weather across the US and other countries La nina is a cooling of the same current which also causes weather changes.