Ocean Currents, and El Nino

The Spherical Earth Latitude – measures distance North or South of the equator Longitude – measures distance East or West from the Prime Meridian Temperate Zones – sun’s rays are never perpendicular Polar Zones – 24 hour sunlight in summer and 24 hours darkness in winter Tropical Zones – sun’s rays are perpendicular to the Earth’s surface for the entire year

Wind patterns and the rotating Earth Without the Earth’s rotation: Air moving from the Equator would cool by 30 degrees latitude and fall to return to the equator or move to the poles Air travelling from the poles would warm up by 60 degrees latitude and rise up to return to the poles

The Coriolis effect is the influence of the Earth’s rotation on air or any object moving on the Earth’s surface In the Northern hemisphere, this causes wind to blow to the right (clockwise) In the Southern hemisphere, this causes wind to blow to the left (counter-clockwise)

The jet stream are ribbons of extremely fast moving air near the top of the troposphere It is caused by contact between the cold and warm air and is found at the boundaries between the polar and temperate zones and the temperate and tropical zones Weather north of the jet stream is cold, weather below it is warm

Ocean Currents Surface currents are caused by wind and carry warm and cold water all over the globe

The ability to carry heat and maintain the temperature over long distances is due to the high heat capacity of water The Coriolis effect causes the ocean currents to flow clockwise in the North and counter-clockwise in the South

The currents in oceans appear to move in a circular pattern called gyres. The right side of gyres has cool water and the left side holds warm water (both affect weather on the land).

Deep Ocean Currents are not caused by wind Deep Ocean Currents are not caused by wind. Instead the currents are caused by cold water sinking and warm water rising, as well as the fact the salt water is more dense than fresh water. A combination of deep and surface currents caused the “great ocean conveyor belt” which moves water around the world.

El Nino Wind blows west from Peru to Australia. This causes an upwelling of cold, nutrient rich water near Peru which also moves west to Australia causing rain there. During an El Nino year, a warming of these cool waters occurs because the trade winds reverse and blow from Australia to Peru.

Hot/Cold Currents Warm Currents: Gulf Stream, Alaskan, Kuroshio, Brazil, South Equatorial, North Equatorial, East Australian, North Atlantic, North Equatorial, East Australian Cold Currents: West Wind Drift, Humboldt, California, Canary, Bengula, West Australian, Labrador, Gulf Stream,

Ocean Currents There are two types of ocean currents: Surface Currents: These are wind driven, they occur in about 10% of the ocean water, but cover the entire ocean surface. Thermohaline Currents: (thermo = heat and haline = salt) These are density driven currents. They occur deeper in the ocean in about 90% of the ocean water.

Surface Currents Surface currents are mostly horizontal currents. These currents follow the pattern of the wind. They occur from the surface down to a few hundred meters. Generally travel clockwise in the northern hemisphere and counter clockwise in the southern hemisphere.

Deep Thermohaline currents are driven by density and temperature changes in the water. These currents are also known as the “ocean’s conveyor belt” They flow under the surface of the ocean and move significant amounts of ocean water vertically.

Why Are Surface important? Surface currents for the general “mixing” of the worlds oceans and waters Surface Currents will move nutrients from more productive areas to less productive areas of the worlds oceans. They are also important in migration and the movement of many less active (or passive) organisms.

Why Thermohaline (Deep) Currents important? These create “upwells” Upwells are: the movement of water from the much deeper water too shallow waters through out the Ocean This makes so all ocean nutrients don’t end up settling on the bottom of the ocean. This mixing makes it so surface organisms can sustain life.