Research Earth Science AgendaFebruary 28, Tuesday: A Day

Take out your CH #22 Agenda with work, AND your GIZMOS activity Take out your test corrections.

o Staple your answer sheet to your corrections sheet.o I will collect these as you do warm-ups

WARM-UPS : We will go over these warm-ups from the last 2 classes!1. Differentiate between High tide and Spring Tide2. Differentiate between Spring tide and Neap tide3. Explain the relationship between the “Tidal Bulge”, High tide, and the Moon’s position with

respect to Eartha. Why are there TWO tidal bulges that are opposite one another?

4. Why is there a relationship between moon phases and tides?

OBJECTIVES : OCEANOGRAPHY1. GIZMOS: TIDEs

a. REVIEW the Gizmos activityb. Short Quiz – you may use your gizmos

2. Review of the February 22 Activities3. Bill Nye: Oceanography

HOMEWORK:1. Be sure you completed your Meteorology TEST CORRECTIONS2. Read the Information on the Global Ocean Conveyor Belt (deep ocean

circulation)3. Look through the NEW OCEANOGRAPHY LABS (there are 2)

a. REVIEW all the information on salinity, ocean water temperatures, and tides!

commerce.govnoaa.govThe global ocean conveyor belt is a constantly moving system of deep-ocean circulation driven by temperature and salinity

The great ocean conveyor moves water around the globe.

The ocean is not a still body of water. There is constant motion in the ocean in the form of a global ocean conveyor belt. This motion is due to thermohaline currents (thermo = temperature; haline = salinity). Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and rises to the surface.

The ocean conveyor gets it “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters are able to warm and rise to the surface, continuing the conveyor belt that encircles the globe.

It takes almost 1,000 years for the conveyor belt to complete one “cycle.”

For more information:The Global Conveyor Belt, NOS EducationOcean Conveyor Belt, NOAA Science on A Sphere

NOAA SitesNational Oceanic and Atmospheric Administration

Deep Ocean Currents (Global Conveyor Belt)Invisible to us terrestrial creatures, an underwater current circles the globe with a force 16 times as strong as all the world's rivers combined [source: NOAA: "Ocean"]. This deep-water current is known as the global conveyor belt and is driven by density differences in the water. Water movements driven by differences in density are also known as thermohaline circulation because water density depends on its temperature (thermo) and salinity (haline).Density refers to an object's mass per unit volume, or how compact it is. A heavy, compact bowling ball is obviously going to be denser than an air-filled beach ball. With water, colder and saltier equals denser.At the earth's poles, when water freezes, the salt doesn't necessarily freeze with it, so a large volume of dense cold, salt water is left behind. When this dense water sinks to the ocean floor, more water moves in to replace it, creating a current. The new water also gets cold and sinks, continuing the cycle. Incredibly, this process drives a current of water around the globe.The global conveyor belt begins with the cold water near the North Pole and heads south between South America and Africa toward Antarctica, partly directed by the landmasses it encounters. In Antarctica, it gets recharged with more cold water and then splits in two directions -- one section heads to the Indian Ocean and the other to the Pacific Ocean. As the two sections near the equator, they warm up and rise to the surface in what you may remember as upwelling. When they can't go any farther, the two sections loop back to the South Atlantic Ocean and finally back to the North Atlantic Ocean, where the cycle starts again.The global conveyor belt moves much more slowly than surface currents -- a few centimeters per second, compared to tens or hundreds of centimeters per second. Scientists estimate that it takes one section of the belt 1,000 years to complete one full circuit of the globe. However slow it is, though, it moves a vast amount of water -- more than 100 times the flow of the Amazon River. [source: NOAA: "Currents"].The global conveyor belt is crucial to the base of the world's food chain. As it transports water around the globe, it enriches carbon dioxide-poor, nutrient-depleted surface waters by carrying them through the ocean's deeper layers where those elements are abundant. The nutrients and carbon dioxide from the bottom layers that are distributed through the upper layers enable the growth of algae and seaweed that ultimately support all forms of life. The belt also helps to regulate temperatures.Read on to learn about a current that isn't caused by winds or density differences but by forces that are out of this world.FAST FACTA well-known density-driven current occurs where the saltier Mediterranean Sea empties into the Atlantic Ocean. During World War II, submarines used this current to enter and leave the Mediterranean without even turning on their engines!