Density & Buoyancy
What do we call how tightly packed matter or molecules are in a substance?
Density
What word describes how salty water is?
Salinity
What is a current?
A steady flow of water in a regular pattern in the ocean.
What is a wave?
The up-and-down movement of surface water; movement of energy through water
What causes tides on Earth?
The Moon’s gravity pulling on the ocean; combined with Earth's rotation
If an object’s density is greater than water’s density, will it sink or float?
Sink
Name two factors that affect ocean salinity.
Depth, melting icebergs, evaporation rates, runoff from land
What is the name of the large ocean current that moves warm water from the Gulf of Mexico towards Europe?
The Gulf Stream
What causes most surface waves?
Wind blowing across Earth's surface.
What is a spring tide and when does it occur?
When the Earth, Sun, and Moon are alligned there are higher high tides and lower low tides. Happens during full and new moons.
Which type of ocean water is denser: cold or warm?
Cold
What is the scientific name for the dissolved solid in ocean water?
NaCl (sodium chloride, salt) dissolves and separates into sodium and chloride.
What two factors listed in the notes help drive ocean currents?
Steady winds and differences in water density (cold/salty).
List three things that affect the size of a wave.
Wind speed, how long the wind blows, and the distance the wind travels over the water
What is a neap tide and when does it occur?
Less extreme tides (lower high tides and higher low tides) that occur when the Sun and Moon are at right angles relative to Earth. Happen during first- and third-quarter moon phases.
Explain why saltwater makes objects more buoyant than freshwater.
Saltwater is denser, so it pushes up with more force, increasing buoyancy.
Which freezes at a lower temperature: freshwater or saltwater?
Saltwater
What is the Coriolis Effect?
The apparent deflection of moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere caused by Earth's rotation.
What part of a wave is the highest point and what is the lowest point called?
Crest is highest; trough is lowest)
Why might fishermen, boaters, and coastal engineers use tide charts?
To know when high and low tides occur so they can plan safe navigation, fishing, and coastal work or construction.
A block floats in freshwater but sinks in another liquid. What does that tell you about the other liquid’s density compared to the block and to water?
The other liquid must be less dense than the block but more dense than freshwater—or restated: the block’s density is less than freshwater and more than the other liquid.
Give the approximate freezing point of typical ocean saltwater in degrees Celsius.
−1.9°C
Explain how denser water helps create deep ocean currents.
Denser (cold, salty) water sinks and flows along the deep ocean, creating deep currents that move water long distances,
Explain why waves slow down and break as they reach shore.
In shallow water the bottom of the wave slows more than the top; the top moves ahead and falls over, causing the wave to break.
The Bay of Fundy has very large tidal differences. Briefly describe what causes unusually large tides in some locations.
Local basin shape and coastline geometry amplify tidal bulges; when tidal forces move water into a narrowing bay with the right natural period, tides become much larger.