Oceans (Unit 8A) Flashcards
What is oceanography?
The science of our oceans that mixes biology, geology, chemistry, and physics to unravel the mysteries of our seas
What percentage of Earth’s ocean water is the pacific ocean?
44%
What percentage of Earth’s ocean water is the Atlantic ocean?
28%
What percentage of Earth’s ocean water is the Indian ocean?
19%
What percentage of Earth’s ocean water is the Southern/Antarctic ocean?
5%
What percentage of Earth’s ocean water is the Arctic ocean?
4%
Average depth of the Pacific ocean:
2.7 miles
Average depth of the Atlantic ocean:
2.4 miles
Average depth of the Indian ocean:
2.4 miles
Average depth of the Arctic ocean:
0.65 miles
Pacific ocean characteristics:
largest and deepest, mountain building along convergent boundaries, ring of fire, volcanic islands, mariana trench
Atlantic ocean characteristics:
2nd largest ocean, mid-atlantic ridge, few islands, large sediment deposits from rivers, Amazon and Congo- 25% of world’s river discharge
Indian ocean characteristics:
3rd largest ocean, mostly in southern hemisphere, abundant fresh water due to river discharge (Ganges, Brahmaptura, Indus)
Southern (Antarctic) ocean characteristics:
Defined in the year 2000, starts at 60 degree south latitude and surrounds Antarctica
Arctic ocean characteristics:
Smallest and shallowest, surrounds North Pole, almost completely surrounded by land, covered with sea ice most of the year, extension of the Atlantic
The global ocean covers [ ] percent of the Earth’s surface
71%
The global ocean makes up [ ] percent of all water on Earth
97%
What causes tides?
Gravitational force of the sun and the moon
Does the sun or the moon have a bigger influence on tides?
the moon
What is tidal range?
the difference in ocean level between high and low tides
Where is the tidal range greatest at?
Bay of Fundy
Diurnal tidal pattern:
1 high, 1 low each lunar day
Semidiurnal tidal pattern:
2 high, 2 low of similar height each lunar day
Mixed tidal pattern:
Characteristics of both, significantly different heights
What is a tidal bore and what causes it?
A “true tidal wave”, moves up a low-lying river, “surf-able”. Caused by incoming high tide
During a neap tide, what angle is the Earth-Moon-Sun system?
right angle
During a spring tide, what angle is the Earth-Moon-Sun system
aligned (one straight line)
Neap tide- (type of: interference, tidal range, moon phases)
Destructive interference, small tidal range (higher than normal low tides, lower than normal high tides), occurs during 1st and 3rd quarter moon phases
Spring tide- (type of: interference, tidal range, moon phases)
Constructive interference, larger tidal range (lower than normal low tides, higher than normal high tides), occurs during full and new moon phases
ENSO stands for:
El nino southern oscillation
Normal year: Western pacific conditions
low pressure, rainy, warm
Normal year: Eastern pacific conditions
high pressure, dry, cold
During a normal year, thermocline location [ ], and trade wind direction is from [ ]
upwelling , east to west
El nino year: Western pacific conditions
high pressure, dry, cold
El nino year: Eastern pacific conditions
low pressure, rainy, warmer than normal
During an el nino year, thermocline location [ ], and trade wind direction is from [ ]
flattens , west to east
La nina year: Western pacific conditions
low pressure, very rainy, warm
La nina year: Eastern pacific conditions
High pressure, dry, extremely cold
During la nina year, thermocline location [ ], and trade wind direction is from [ ]
Increases , east to west
In the United States we are affected by which pacific conditions?
East
Northern Hemisphere is aka [ ] because it is [ ] percent of land
land , 39%
Southern hemisphere is aka [ ] because it is only [ ] percent of land
Water , 19%
3 reasons why ocean circulation is important
transports heat from equator to poles, transport nutrients & organisms, influences weather & climate
surface ocean currents are caused by [ ] driven by the [ ]
winds , Corriolis effect
Surface currents are also known as… ?
gyres
Surface currents in the Northern hemisphere move in what direction?
clockwise
Surface currents in the Southern hemisphere move in what direction?
counterclockwise
warm currents are [ ] and cool currents are [ ]
fast , slow
Thermohaline
Convective circulation caused by temperature & salinity
Upwelling
force that vertically moves cooler, nutrient-rich water up from the deep ocean
What is the driving force behind deep ocean circulation
upwelling
Salinity
Amount of dissolved salt water, usually expressed in parts per thousand (ppt)
Average salinity:
33-38 ppt, approx. 3.3%-3.8%
What three things do salts come from
weathering & erosion of rocks and minerals, outgassing from Earth’s interior, and hard parts of marine organisms
To increase salinity-
remove water: through evaporation and formation of sea ice
To decrease salinity-
add water: through precipitation and sea ice melting
[ ] varies with depth because of the thermocline
Temperature
Thermocline
where warm water rapidly changes to cool water
rapid decrease in temp with depth
near equator
no rapid change in temp with depth
near poles
density depends on
salinity and temperature
what determines water’s vertical position in the ocean
density
more dense water is
cooler and salty, it sinks
Least dense water is
warm and not salty, it rises
Study of ocean floor features
bathymetry
first major scientific study of the oceans was by the
HMS challenger
shallow water area found in proximity to continents
continental margin
submerged edge of the continent, gentle slope away from shore, lots of resources
continental shelf
steep slope from the continental shelf to the ocean
continental slope
raised wedge at the base of the continental slope; sediment collects here
continental rise
a valley that cuts into the continental shelf and slope; caused by underwater river flow or earthquakes
submarine canyons
SUPER deep, v-shaped underwater valley, formed at convergent plate boundaries
deep-ocean trenches
flat area of deep-ocean basin; covered in sediment
abyssal plains
submerged volcano, possibly active
seamounts
flat-topped, inactive submerged seamount, aka “tablemount”
guyots
underwater mountain range at divergent boundary; site of hydrothermal vents
ocean ridges
island formed by coral around an extinct volcano, “coral reef”
atolls
