4.1 Introduction to water systems Flashcards
What factors cause ocean currents?
- Wind
- Tides
- Changes in water density
- Rotation of the earth
What is the main driving factor of ocean currents at different levels?
- Surface currents - wind
- Deep ocean currents - density of sea water
What is “thermohaline circulation”?
North Pole - water gets colder and has a higher concentration of salt
Cold salty water = more dense
–> sinks
Moves towards the equator to replace the warm water
(This initiates the deep-ocean currents driving the global conveyer belt.)
What kind of water is more dense?
Cold and salty water = more dense
Why is the ocean important?
- Determines climatic patterns around the globe by adding different amounts of moisture to the atmosphere
- Serves as a store of atmospheric gases that help regulate the composition of the atmosphere
What does it mean when water has a higher “specific heat capacity” than land?
This means the water masses heat up and cool down more slowly than land masses.
–> Lands close to seas have a milder climate
What are some of the functions of “ocean currents”?
Mass flows of water, or currents, are essential to understanding how heat energy moves between Earth’s water bodies, landmasses and atmosphere
Has a higher specific heat capacity than land. This means the water masses heat up and cool down more slowly than land masses.
(eg. Lands close to seas have a milder climate)
The movement of heat through local and global ocean currents affects:
–> regulation of local weather conditions
–> stabilisation of global climate patterns
–> delivery of nutrients and larvae to marine ecosystems
What are some properties of “warm surface currents”?
- Flow away from the equator
- Warm water rises to the ocean surface as it is less dense
- As the water moves away from the equator it slowly cools down
- A warm current increases the air temperature –> enables the air to carry more moisture which then again reduces the higher temperatures
eg. Gulf stream
What are some properties of “cold surface currents”?
- Flow from the poles to the equator
- Cold water moves south to fill in the ‘gap’ left by the warm water
- Cold currents move in deeper waters, as they are usually colder than the water above it
- Higher salinity (more salt = denser)
Explain the loop of the “oceanic conveyor belt”?
The ocean conveyor gets its “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 returns to the surface through mixing and wind-driven upwelling, continuing the conveyor belt that encircles the globe.
Why is the “oceanic conveyor belt” so important?
- The conveyor belt brings oxygen to the bottom of the ocean
What is the impact of climate change on the “oceanic conveyor belt”?
- It is driven by differences in salinity and temperature
–> CLIMATE CHANGE - These differences become smaller, and thus the global oceanic conveyor belt is reduced, and that could start our mass extinction
How do global ocean currents move?
- Deep water currents make up 90% of ocean current
- Due to differences in water density caused by salt and temperature
–> cold water holds more salt –> denser –> sinks
–> warm water holds less salt –> less dense –> rises - When warm water rises, cold water comes up from the depths to replace it = upwellings
- When cold water rises it has to be replaced by water water in downwellings
- In this way water circulates
- Cold ocean currents run from the poles to the equator
How does the current affect climate?
Water has a higher specific heat capacity than land. Water masses heat up and cool down more slowly than land masses. Land close to seas and oceans has a milder climate. Currents can also bring higher temperatures..
What is the “water cycle”?
The water cycle is driven by the Sun. It consists of storages of water and the flows of water between the various storages.
Which term corresponds to the red box in the image? (water cycle)
atmosphere
Which term corresponds to the red box in the image? (water cycle)
condensation
Which term corresponds to the red box in the image? (water cycle)
evaporation
Which term corresponds to the red box in the image? (water cycle)
infiltration
Which term corresponds to the red box in the image? (water cycle)
percolation
Which term corresponds to the red box in the image? (water cycle)
precipitation
Which term corresponds to the red box in the image? (water cycle)
run off
