Ocean currents

A Current is the motion of water. The currents in the ocean can be divided into two main types. The upper km of the ocean is governed by the wind whereas the deeper parts of the ocean are affected by mixing of deeper currents to create water with varying density.

Surface currents:

They make up 10% of all the oceans water and is controlled by the wind. The surface currents are dominated by Gyres. So what are Gyres.....

Gyres are, in the simplest of terms, a large system of rotating ocean currents. They are caused by the wind blowing on the water pushing it in a direction. When the coriolis force pushes against the wind direction gyres form from this rotational pattern.

There are 5 major Gyres:

Indian Ocean Gyre

North Atlantic Gyre

North Pacific Gyre

South Atlantic Gyre

South Pacific Gyre

All of the major gyres can be seen in the map above. A lot of the research i have done on this topic has unearthed a large quantity of environmental studies in ocean pollution. The predominat topic are the major garbage patches which have formed in the oceans, this will be covered in my next blog post.


Deep Ocean currents:

These ocean currents make up 90% of the oceans water and mainly determined by water density.

The Thermohaline Circulation

This is a density driven current which involves an overturning of water to create different density pockets with varying temperaratures. This circulation moves warm water polewards where it is then converted into cold water which sinks and flows down towards the equator.

The two main interconnected processes are:

1) Deep convection
2) Upwelling through the rest of the ocean to bring the cold water back to the surface

Why is the conveyor belt so important?

The Thermohaline circulation has a major impact on the global climate. The circulation is the main supplier of heat to the polar regions and thus controls the levels of ice in this area. This is so vital as any slight changes in global temperatures are known to have a dramatic effect on sea levels rising due to melting areas of ice.

Although it is not known for certain the level the THC affects global climate, it is believed to affect the radiation budget and alongside this largely influence levels of carbon dioxide in the atmosphere.

This falls into the climate change category which i will focus on in some of my later blogs. I will look specifically at how changes in climate effect certain weather patterns such as Hurricanes and Ocean currents.

Tasks for the classroom:

This was a difficult one as although i find the oceans quite enthralling due to the vast size of them and their influence on the world trying to find exciting tasks which will enhance learning has not been easy. As my next topic about the oceans is about the shutdown of the THC i might set them a task to research the effects of this might be on the world.

Random facts:

- 90% of all volcanic activity occurs in the oceans.
- The speed of sound in water is 1,435 m/sec - nearly five times faster than the speed of sound in air.
- Less than 10% of our oceans have been explored by humans
- Mt Everest is more than 1 mile shorter than the deepest part of the ocean. Challenger Deep is 6.86 miles deep.