Deep Sea Currents

Deep Sea​
Currents

​Water is weird.

​It's written like this....

​H₂O

​...and looks like this.

71% of the Earth is covered in it.

We'll get to the drinkability conversation next unit but for now lets focus on the salt water stuff.

Multiple Choice

What is the formula for density?

• density = weight/volume
• density = volume/mass
• density = mass x volume
• density = mass/volume

Multiple Choice

What is density?

• Density is a measure of how much energy is contained in a given volume.
• Density is a measure of how much space an object occupies.
• Density is a measure of how much mass is contained in a given volume.
• Density is a measure of how much weight is contained in a given volume.

Water is most dense at 4^o C.

​
Also...it freezes from the top down.

​Other ways water is weird.

Other substances become more dense as they get colder and freeze from the bottom up...

...but water does its own thing.

​

Temperature changes density.

So when water changes temperature, the water at 4^o C moves to the bottom, pushing colder water up. (convection)

​This is because more dense objects sink.

​Other things affect density

• Water's density can also change based on salinity.

  • salinity: the amount of salt in a solution.

  • 3.5% of the global ocean weight comes from dissolved salts.

  • It would leave behind a layer 15 stories high.

Salt makes cubes

Water forms hexagons

​Remember this structure?

​It makes that.

The cube can't fit in the hexagon.

So when water freezes, salt is pushed out.

​In the case of sea ice, salt is pushed down.

This makes the water under the ice denser. (convection)

It's coming from temperature and salinity changes. What does this mean?

​

​So this convection stuff...

Multiple Choice

In what direction is the water convecting?

• Horizontally

• Vertically

All this convecting makes a global conveyer belt.

Also known as the thermohaline.

​Thermo: heat

Haline: salt

​Takes 1000-2000 years to complete a full circulation.

Multiple Choice

What changes water density?

• Temperature and salinity
• Volume and weight
• Color and taste
• Pressure and pH

Multiple Choice

What happens to salt as sea water freezes?

• The salt dissolves in the water and becomes invisible.
• The salt turns into gas and escapes into the atmosphere.
• The salt evaporates and disappears.
• The salt is left behind and forms ice without the salt.

Multiple Choice

What is another name for the deep sea global conveyer belt?

• marine circulation
• oceanic conveyor belt
• deep ocean current
• thermohaline circulation

Multiple Choice

What direction do deep sea currents move?

• Stationary
• Diagonal

• Vertical
• Horizontal

Multiple Choice

In the deep sea conveyer belt, warm water moves in what direction?

• from the equator towards the poles
• from the west towards the east
• from the east to the west

• from the poles towards the equator

Multiple Choice

How long does it take for the thermohaline circulation to complete one cycle?

• 1000 years
• 500 years
• 50 years
• 10 years