1. 1. Kevin goes bowling. Whenever he bowls the ball, he transfers energy from his hand to the bowling ball. The amount of energy before the transfer is ____________ the amount of energy after the transfer.
A. more than
B. equal to
C. less than
D. not related to
2. The law of _______ of energy states that energy cannot be created or destroyed.
A. stability
B. conservation
C. absorption
D. transformation
3. A light bulb is turned on. It produces light and warms up. Which statement is true?
A. All the electrical energy is transformed to light energy.
B. Some of the electrical energy is transformed to light energy and some is destroyed.
C. All the electrical energy is transformed to heat energy.
D. All the electrical energy is transformed to light energy and heat energy.

2. Deep Currents

3. Deep Currents What are deep currents?
They are stream like movements of ocean water located far below the surface. Unlike Surface Currents, Deep currents are not controlled by wind. They are formed where parts of the ocean waters density increases.

4. What’s Density Density simply put, is how heavy the water is.
Cold water is more dense then warm water because the water molecules get closer together
Warm water is less dense then cold water because the water molecules spread apart
Remember in convection ( warm rises and cold sinks)
Oceans are also affected about the amount of salt in the water more salt means higher density.

6. Deep Currents
Streamlike movements of ocean water located far below the
surface are called deep currents. Unlike surface currents, deep
currents are not directly controlled by wind. Instead, deep currents form in parts of the ocean where water density increases.
Density is the amount of matter in a given space, or volume.
The density of ocean water is affected by temperature and
salinity—a measure of the amount of dissolved salts or solids in
a liquid . Both decreasing the temperature of ocean water and
increasing the water’s salinity increase the water’s density.

7. Deep Currents What contributes to the formation of deep Currents?
Decreasing temperatures and increasing salinity causes a difference in density and contribute to the formation of deep currents.

8. Formation and Movement of Deep Currents
Differences in temperature and salinity—and the resulting differences in
density—cause variations in the movement of deep currents.
For example, the deepest current, the Antarctic Bottom Water,
is denser than the North Atlantic Deep Water. Both currents
spread out across the ocean floor as they flow toward each
other. Because less-dense water always flows on top of denser
water, the North Atlantic Deep Water flows on top of the
Antarctic Bottom Water when the currents meet.

9. Three factors contribute to the formation of deep currents.

10. 1. Decreasing Temperature
In Earth’s polar regions, cold air chills the water molecules at the ocean’s surface, which causes the molecules to slow down and move closer together. This reaction causes the water’s volume to decrease. Thus, the water becomes denser. The dense water sinks and eventually travels toward the equator as a deep current along the ocean floor.

11. 2. Increasing salinity through freezing.
If the ocean water freezes at the surface, ice will float on top of the water because ice is less dense than liquid water. The dissolved solids are squeezed out of the ice and enter the liquid water below the ice. This process increases the salinity of
the water. As a result of the increased
salinity, the water’s density increases.

12. 3. Increased Salinity through Evaporation.
Another way salinity increases is through evaporation of surface water, which removes water but leaves solids behind.
This process is especially common in
warm climates. Increasing salinity through evaporation causes water to become denser, to sink to the ocean floor, and to form a deep current.

13. Thermohaline circulation drives a global-scale system of currents called the “global conveyor belt.” The conveyor belt begins on the surface of the ocean near the pole in the North Atlantic. Here, the water is chilled by arctic temperatures. It also gets saltier because when sea ice forms, the salt does not freeze and is left behind in the surrounding water. The cold water is now more dense, due to the added salts, and sinks toward the ocean bottom. Surface water moves in to replace the sinking water, thus creating a current.
Cold, salty, dense water sinks at the Earth's northern polar region and heads south along the western Atlantic basin.

14. This deep water moves south, between the continents, past the equator, and down to the ends of Africa and South America. The current travels around the edge of Antarctica, where the water cools and sinks again, as it does in the North Atlantic. Thus, the conveyor belt gets "recharged." As it moves around Antarctica, two sections split off the conveyor and turn northward. One section moves into the Indian Ocean, the other into the Pacific Ocean.
The current is "recharged" as it travels along the coast of Antarctica and picks up more cold, salty, dense water

15. These two sections that split off warm up and become less dense as they travel northward toward the equator, so that they rise to the surface (upwelling). They then loop back southward and westward to the South Atlantic, eventually returning to the North Atlantic, where the cycle begins again.
The main current splits into two sections, one traveling northward into the Indian Ocean, while the other heads up into the western Pacific.

16. What is upwelling?
Upwelling is a process in which deep, cold water rises toward the surface
Winds blowing across the ocean surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as “upwelling.”
Upwelling occurs in the open ocean and along coastlines. The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom.
Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity.  Therefore, good fishing grounds typically are found where upwelling is common.

17. This graphic shows how displaced surface waters are replaced by cold, nutrient-rich water that “wells up” from below.

18. The conveyor belt moves at much slower speeds (a few centimeters per second) than wind-driven or tidal currents (tens to hundreds of centimeters per second). It is estimated that any given cubic meter of water takes about 1,000 years to complete the journey along the global conveyor belt. In addition, the conveyor moves an immense volume of water—more than 100 times the flow of the Amazon River (Ross, 1995).
The two branches of the current warm and rise as they travel northward, then loop back around southward and westward.

19. The conveyor belt is also a vital component of the global ocean nutrient and carbon dioxide cycles. Warm surface waters are depleted of nutrients and carbon dioxide, but they are enriched again as they travel through the conveyor belt as deep or bottom layers. The base of the world’s food chain depends on the cool, nutrient-rich waters that support the growth of algae and seaweed.
The now-warmed surface waters continue circulating around the globe. They eventually return to the North Atlantic where the cycle begins again.

20. In Review

21. For Fun