SLO 2

Reconstructing the major circulation patterns of the dominant ocean circulation systems, atmospheric circulation systems, and analyzing their interrelations.

Atmospheric circulation is sure a difficult subject to explain but with a few small factors, you can master the main process of how it works. Most of us know warm air rises and cold air sinks. This is due to the density of the air molecules. Taking a look at the left image you will see at the equator (right side of image) the air rises due to the heat coming from the sun. It then cools down as it gets to the atmosphere and sinks back towards the surface at about 30 degrees. This pattern is called the Hadley cell. At the 30-degree mark the air sinks down then warms up along the surface then rises at the 60-degree mark then goes back around to the 30-degree mark. This pattern is called the Ferrel cell. At 60-degrees the hot air rises then rapidly cools at the north pole then gets pushed down along the surface and repeats the cycle at 60-degrees. This pattern is called the Polar cell. These three cells make up the circulation patterns of the Earth. The image below shows this complicated process.

Next, we will talk about oceanic circulation. Atmospheric circulation and oceanic circulation is all intertwined in certain ways. The ocean's currents are made up of two different categories. Surface currents are 10 % of ocean currents and deep ocean currents are 90% of the ocean's currents. Surface currents are driven by winds and tides that pull and push the water. Deepwater currents are driven by the changes in density in the water. Both of these processes are complicated in their own ways but are simple at the same time.

Wind can influence water as deep as 50 - 100 meters. Although the current acts differently according to the Coriolis effect. The wind pulls along the surface of the water and creates friction underneath each layer of water. The underneath layers move a lot slower than the surface layers. With the Coriolis effect added it causes the current to drift about 20 - 45 degrees to the right or left of the wind, depending on what hemisphere you are on. This causes a spiral due to the speed of increased depth of water. This process is called Ekman transport. A very interesting process if you ask me. The next current which makes up about 90% of the currents are deep ocean currents. Deep ocean currents are driven by the changes in density of the water. As water gets to cooler areas, the water becomes more dense due to the amount of salt in the water. Salt has a hard time staying within the glaciers so it all sinks within the remaining water which causes it to be more dense. This water sinks then makes its way towards much warmer areas. This process is called Thermohaline circulation. With these two currents combined, it creates what we call the global conveyor belt.

This is an awesome image demonstrating how thermohaline circulation works. The heat lamp represents the sun and the chunk of ice represents our glaciers. The dense water from the chunk of ice sinks to the bottom then is push along the bottom the warms up when it reaches the surface.

Here is a descriptive image explaining the thermohaline circulation patterns.

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