GS 106 - Introduction to Physical Geology

6) How does thermohaline circulation form? What is its purpose? Try to use the words density, salt, ice, and cold water. (Credit: National Oceanic and Atmospheric Administration, Department of the Interior/NOAA)

Picture: http://www.ncdc.noaa.gov/paleo/ctl/images/belt.jpg

Alt Text: Map showing how thermohaline circulation works and where the current travels over the Earth.

Answer: Thermohaline circulation forms due to an increase of density of water. This increase of density is caused by the formation of ice at the poles. As ice forms, salt is concentrated in very cold ocean water at the poles making that water much heavier. this water will begin to sink and as it sinks it pushes other water out of the way making a world wide density current within the deep ocean.  The purpose of this ocean current is to spread heat from the tropics to the poles, evenly distributing the heat provided by the sun.

7) Based on the location of the formation of deep water in the North Atlantic, near the Greenland Icesheet, how could the flow of the thermohaline circulation be slowed, or even stopped, do to climate warming? (Credit: National Oceanic and Atmospheric Administration, Department of the Interior/NOAA)

Picture: http://www.ncdc.noaa.gov/paleo/ctl/images/belt.jpg

Alt Text: Map showing how thermohaline circulation works and where the current travels over the Earth.

Answer: The way that thermohaline circulation could be stopped would be if a large amount of fresh water was added to the area where the thermohaline circulation forms. Some possible ways that this could happen would be extreme melting of the Greenland ice sheet as the global climate warms. This could send water to the are where deep water forms slowly over time, freshening the water or it could happen all at once, perhaps if a lake drains on the ice sheet or even if a large piece breaks off and melts in the same location.

8) Why do tides occur exactly? Explain in detail using the terms gravitational force, centrifugal force, bulge, and water. (Credit: National Oceanic and Atmospheric Administration , Department of the Interior/NOAA)

Picture: http://oceanservice.noaa.gov/education/kits/tides/media/tide03_480.gif

Alt Text: Picture shows the different forces acting on the Earth that effect ocean water.

Answer: Tides form due to the gravitational force exerted on Earth by the moon, this creates a bulge of water as the moon pulls on the water of the ocean and where this bulge is there should be high tide. There is also another bulge of water created due to centrifugal force of the earth spinning, it causes a bulge to form of the back side of the Earth, farthest from the moon. Where there is no bulge of water, we should have low tide.