density currents Flashcards
what are two factors that affect the density of ocean water
temperature and salinity
what changes salinity?
precipitation = decrease
melting = decrease
run off = decrease
evaporation = increase
freezing = increase
evaporation precipitation and run off are the most influential
what is the unit for salinity?
psu, practical salinity unit
1 psu = 1g of salt / 1 kg of total water
same as ppt, part per thousand, percentage out of 1000
what leads to precipitation and makes the equator more rainy
clouds form when air rises, leading to precipitation
since the warm air from the equator rises, this causes a rainy climate
this is the opposite for areas around 30º latitude
is temperature or salinity more influential to density?
temperature
why is the atlantic denser than the pacific?
it has a smaller surface area, allowing more evaporation to occur
what is thermohaline circulation?
thermohaline circulation is the movement of water based on density
thermo = temperature, haline = salinity, the two factors that affect density
what causes thermohaline circulation?
denser water from high latitudes in the atlantic must sink, but does not rise again like convection currents because there is no heat source on the bottom
instead it rises, upwells, in other locations
it does this by one since it sinks there in at high atlantic latitudes, denser deep water must rise elsewhere
and two by the coriolis affect winds blow surface water away from the shore, allowing cold water to rise to replace it
why is deep water more nutrient rich?
since dead animals and dense nutrients sink, deep water is more saturated with nutrients
this means areas of upwelling are also nutrient dense
what are the three layers in the ocean?
mixed layer: a layer where waters are stirred up by the wind, even temperature and salinity but level dependent on latitude
intermediate layer: conditions depend on latitude, transition from mixed layer to deep layer
deep layer: where cold water sinks, cold saline water from atlantic poles
what are thermocline, pycocline, and halocline?
thermocline is the change in temperature with depth
halocline is the change in salinity with depth
pycocline is the change in density with depth
these phases are marked at the ranges where temperature, salinity, or density change the most before becoming more constant, happen in transition zone
how does climate change affect thermohaline circulation?
if the cold waters in the atlantic wam, they will not sink as much, disrupting thermohaline circulation
this impacts surface currents which impacts climate
why do we say climate change and not global warming to describe the effects of greenhouse gases?
the increase of greenhouse gases can actualy cause climates to becoming cooler
e.g. greenhouse gases can warmice causing melting, affecting salinity, disrupting thermohaline circulation and altering currents, making places like europe cooler, not warmer
what are the three latitude ranges?
low (0-30)
mid (30-60)
high (60-90)
water mass
volumes of water with different properties
