Heat & Density
What usually happens to ocean water when it is heated?
It becomes less dense and rises or stays near the surface.
What word describes the amount of dissolved salt in water?
Salinity
What is the main force that moves surface ocean currents?
Wind
What is transferred around Earth by ocean waves and currents?
Energy, especially thermal energy.
What gas can ocean water absorb from the atmosphere?
Carbon dioxide.
What usually happens to ocean water when it cools?
It becomes denser and sinks.
Which is usually denser: salt water or fresh water
Salt water
Where are surface currents found: near the ocean’s surface or near the ocean floor?
Near the ocean’s surface.
Do ocean currents transport only water, or do they also transport energy?
They transport both water and energy.
How does absorbing carbon dioxide help the ocean regulate the atmosphere?
It removes and stores some carbon dioxide from the air.
In a tank, blue cold water sinks below red warm water. Why?
Cold water is denser than warm water.
What happens to the density of ocean water when its salinity increases?
Its density increases.
Complete the energy chain: Sun → ______ → surface currents.
Wind
How can a warm ocean current affect the air and land nearby?
It can transfer thermal energy to the air and make the nearby climate warmer.
A scientist draws wind arrows and surface-current arrows on the same map. What relationship should the map show?
Surface currents generally move in the same direction as the winds that cause them.
How does heating and cooling produce a convection current?
Warm water rises while cooler, denser water sinks, creating continuous circulation.
A large amount of salt is added to one area of the ocean. How will that water move?
It will become denser and sink.
On a map, global winds blow from west to east. In which general direction should the nearby surface current move?
From west to east, in the same general direction as the wind.
What is upwelling?
The movement of deep ocean water toward the surface.
A current carries warm water from the equator toward a colder region. What is being transferred?
Thermal energy is being transferred from the equator toward the colder region.
Surface water near the poles loses thermal energy to the cold air. Describe what happens next.
The water cools, becomes denser, and sinks, helping form deep ocean currents.
One area contains cold, salty water, while another contains warm, less-salty water. Which water is most likely to form a deep current, and why?
The cold, salty water because both its low temperature and high salinity make it denser.
Explain how energy from the Sun eventually causes surface ocean water to move.
The Sun heats Earth unevenly, creating moving air or wind. The wind transfers energy to the ocean’s surface and produces surface currents.
Why can upwelling occur when warm surface water moves away from an area?
Cooler deep water rises to replace the surface water that moved away, transferring water and energy upward.
Polar water cools and sinks while deep water rises closer to the equator. Explain how these movements are connected.
Differences in temperature and density create circulation. Cold, dense polar water sinks and moves through the deep ocean, while other deep water rises to replace surface water elsewhere.