Ocean Currents Flashcards
What is an ocean gyre?
Circular movement of water caused by temperature differences and Earth’s rotation.
What is a current?
A moving stream of water that has characteristics that are different than the surrounding water.
What is a western boundary current?
The western edge of a gyre where the deeper and faster water is found.
What is an eastern boundary current?
The eastern edge of a gyre where the shallower and slower water is found.
How can density affect ocean currents?
Less dense water will float on top of more dense water. This can move water vertically in the ocean basins.
How can salinity affect ocean currents?
Water with a higher salt content will be more dense
What is a convection current?
Movement of energy throughout a substance by density differences. Warmer, less dense water rises and cooler, more dense water sinks.
What is the Coriolis effect?
The bending of prevailing winds and ocean currents because of Earth’s rotation.
What are the Trade Winds?
Prevailing wind pattern in the areas between the equator and 30 degrees North and South. They move in an easterly direction.
What are the Westerlies?
Prevailing wind pattern in the areas between 30 degrees and 60 degrees North and South of the equator. They move in a westerly direction.
What are the Polar Easterlies
Prevailing wind pattern in the areas between 60 degrees and 90 degrees North and South of the equator. They move in an easterly direction.
What is the thermalhaline (global) conveyor belt?
A global pattern of water circulation in the oceans.
Where are deep water formation areas located?
They are primarily found near the poles where cold temperatures, ice formation, and evaporation produce dense water that sinks to the bottom of the ocean.
What are prevailing winds?
Winds that blow from one direction more frequently than any other.
What is upwelling?
The upward movement of cold, nutrient-rich water.
How does upwelling occur?
The Trade Winds push water away from the western side of continents, allowing cold water to rise and replace it.
What is the Peru Current Large Marine Ecosystem?
An area off the western coast of South America from which approximately 18% to 20% of the world’s fish catch comes.
What is El Nino Southern Oscillation (ENSO)?
A periodic weakening of the Trade Winds, which disrupts upwell along the coast of South America?
What are some effects of El Nino?
Disrupting nutrient flow causes fish to starve. Rainfall patterns in the western Pacific ocean move to the central Pacific ocean. Normally dry areas of the US can experience increased rainfall. Warmer than usual winters occur in the northern US and Canada.
What causes wind?
Wind is the horizontal movement of air caused by pressure differences.
How can temperature differences cause currents?
Warm water will move towards a colder area. Generally water will move on the surface from the equator towards the poles.
How does wind affect water currents?
Prevailing winds can move surface water.
How does the position of continents affect currents?
The continents provide barriers that direct water up and down coastlines in gyres.
How does evaporation affect the salinity of ocean water?
When water evaporates from oceans, freshwater is removed as water vapor, leaving the salt behind. Evaporation will increase salinity.
How does ice formation affect salinity of ocean water?
When water forms ice, only freshwater becomes a solid. The water below the ice retains the salt. Ice formation increases salinity.
How do melting ice sheets affect salinity of ocean water?
Melting ice increases freshwater into the ocean, which dilutes the saltwater. Melting decreases salinity.
Why is cold water more dense than warm water?
The water molecules are moving slower, which allows them to move closer together. More water molecules in a given volume is greater density.
How do ocean currents affect land temperatures?
A warm ocean current will warm the air around the land it passes. Since water has a high heat capacity, warm water can move large distances and remain warm. This can make some areas warmer than others at the same latitude. Cold currents will absorb heat energy from the air around the land they pass. This can make land temperatures colder than other areas at the same latitude.
How do hurricanes form and move in the Atlantic ocean?
Hurricanes will form off the coast of Africa. They will move with the equatorial current across the Atlantic, absorbing heat energy from the warming water.
Why are areas near the equator warmer than areas near the poles?
The Earth’s spherical shape causes the Sun’s rays to be more direct and intense near the equator.
