Atmospheric & Ocean Circulation

how is heat transferred around the globe?

through conduction, radiation, & latent heat (phase change)

what is conduction?

the transfer of heat through direct contact between the surface & the atmosphere

what is radiation?

emission of heat/energy

what is latent heat?

the largest pathway for heat exchange between the land or oceans & the atmosphere

how does phase change occur?

heat released or absorbed when water moves between solid, liquid, & vapor forms

what are convection cells?

circular patterns of fluid movement caused by temperature differences, where warmer, less dense fluid rises & cooler, denser fluid sinks, driving heat transfer

what happens to warm air during convection?

holds more water & expands & rises as it warms (low pressure)

what happens to cold air during convection?

cold, dry air sinks

what happens when air rises during convection?

it condenses, cools & releases water (high pressure)

what happens when air sinks during convection?

picks up moisture as it warms back up at the surface

what is the coriolis effect?

the deflection of moving objects (air & water currents) caused by the rotation of the earth; influences weather patterns & ocean currents, causing them to curve right in the northern hemisphere & left in the southern hemisphere.

what causes the coriolis effect?

different latitudes rotate at different speeds to complete a full rotation; some points must travel further & faster than others (equator vs poles)

how would global atmospheric circulation look without coriolis?

a single convection cell in each hemisphere; warm air rises at the equator, moves towards the poles, sinks, & returns to the equator, leading to direct north-south winds

what are the major circulation cells?

hadley, ferrel, polar cells

what are the hadley cells?

convection cells created by rising air at the equator & sinking air at 30^o; one at each hemisphere

what are polar cells?

cold air that descends at the poles moves over the earth’s surface towards the equator, & by about 60^o latitude it begins to rise

what are ferrel cells?

composed of sinking air at 30^o & rising air at 60^o

what are the surface winds?

easterlies & westerlies

what are easterlies?

dominant winds found between 60^o & the poles in both hemispheres

what are westerlies?

dominant winds between 30^o & 60^o in both hemispheres

what are the trade winds?

winds between the equator & 30^o latitude; northeast trade winds in the northern hemisphere & southeast trade winds in the southern hemisphere

what are in between the wind bands?

regions of high & low pressure; high pressure zones occur where air is descending, while low pressure zones indicate rising air

what are doldrums?

along the equator the rising air creates a low pressure region; aka intertropical convergence zone (ITCZ) where the trade winds converge

what are horse latitudes or subtropical highs?

at 30^o latitude there are high pressure zones of descending air

what are polar fronts?

at 60^o lies another low pressure region

how does global atmospheric circulation relate to global climate patterns/habitat distribution?

due to global atmospheric circulation, equator tends to be warm & humid, while polars are colder & drier; ecosystems & species depend on climate

how does the coriolis effect impact ocean currents?

deflects ocean currents right in the northern hemisphere & left in the southern hemisphere, creating ocean gyres (surface currents that flow around the periphery of an ocean basin)

what is the geostrophic balance?

the balance between the pressure gradient force & the coriolis force, resulting in flow along lines of equal pressure (isobars)

what are the five ocean gyres?

north pacific, south pacific, north atlantic, south atlantic, indian oceans

how are ocean gyres formed?

wind patterns, earth's rotation (coriolis effect), & the shape of the continents (western, eastern & transverse currents)

what makes the gulf stream special?

a powerful, warm, & swift ocean current that transports vast amounts of heat from the tropics to higher latitudes, significantly influencing the climate of the eastern US & western europe, making the latter warmer than it would otherwise be. 

what makes the antarctic circumpolar current special?

the only ocean current that flows completely around the globe, connecting the atlantic, pacific, & indian oceans; regulates global climate & ocean circulation

what is western intensification?

currents of the western side of the gyre are much more intense than currents of the eastern side; currents off the east coast of the continents are more intense than currents off the west coast of the continents

why does western intensification occur?

result of the way the coriolis effect changes with latitude

how does western intensification impact boundary currents?

leads to a steeper slope of surface water on the western side of a gyre compared to the eastern side, resulting in faster-moving, more concentrated currents

what is an eddy?

a circular current of water that forms when sections of water pinch off from larger currents (gyres), often transporting heat, nutrients, & marine life

how do warm core eddies move?

clockwise rotating warm core eddies move west

how do cold core eddies move?

counterclockwise rotating cold core eddies move east

what currents do not form eddies?

eastern boundary currents

where does plastic accumulate?

center of gyres

what is ocean/surface convergence?

water driven together by the wind or against a coast; downwelling

what is ocean/surface divergence?

wind blows surface waters away from an area or coast; upwelling

what are the different types of upwelling?

coastal, equatorial, antarctica, eddies

what drives coastal upwelling?

alongshore winds that push surface water away from the coast, leading to the replacement of that water by nutrient-rich, deeper water

what drives equatorial upwelling?

the trade winds & the earth's rotation (coriolis effect); causes surface waters to diverge away from the equator, allowing deeper, nutrient-rich water to rise & replace it

what drives antarctica upwelling?

strong westerly winds around the continent, create a divergent surface flow, drawing up deep, nutrient-rich waters

what drives cold-core eddy upwelling?

polar fronts that create a divergent surface flow & draw up deep, nutrient-rich waters

what is el niño southern oscillation (ENSO)?

a naturally occurring climate pattern that involves fluctuations in the sea surface temperatures in the central & eastern equatorial pacific ocean (2-7 year cycle)

what is el niño?

the "warm" phase of ENSO, characterized by unusually warm ocean temperatures along the equatorial pacific due to weakened trade winds; wet conditions, little upwelling

what is la niña?

the "cold" phase of ENSO, characterized by unusually cold ocean temperatures in the central and eastern pacific due to stronger trade winds; dry conditions, strong upwelling

what drives salinity?

precipitation, evaporation, ice formation

what drives temperature?

heating & cooling

where do the drivers of salinity & temperature occur at?

the ocean surface

what is the density stratification of ocean?

high density water always sinks

where is the surface mixed layer?

0-100m, changes with depth

where is the pycnocline?

100-1000m, changes with depth

where is the deep layer?

below 1000m, changes with depth

what is thermohaline circulation?

a global system of deep-ocean currents driven by density differences caused by temperature (thermo) & salinity (haline) variations, moving heat & nutrients around the planet

where is deep water formed?

at the surface, north atlantic ocean

why does deep water form at the surface?

cold, salty water becomes dense enough to sink

where is deep water youngest?

where its formed, the atlantic

where is deep water oldest?

the (north) pacific

what happens when water moves through the ocean conveyor belt?

loses O2 & gains CO2 & nutrients (lowers pH)

what is the atlantic meridional overturning circulation (AMOC)?

a system of ocean currents that transports warm water from the tropics north into the north atlantic, where it cools, sinks, & flows south

what is the continuity of flow?

dense water sinks & spreads horizontally, must be replaced at surface

what can slow down the ocean conveyor belt/AMOC?

increased melting of glaciers & ice sheets; introduces freshwater into the north atlantic, diluting the salty water & reducing its density, weakening the sinking motion that drives the current

what defines a water mass?

a large body of water with similar temperature & salinity throughout

what are the four major water masses in the north atlantic?

antarctic bottom water, north atlantic deep water, mediterranean outflow water, antarctic intermediate water

what is caballing?

when two water parcels with different temperatures & salinities mix to form a new water parcel that is denser than either parent, causing the new water to sink

what is the relationship between upwelling & changes to surface layer?

upwelling increases nutrients, CO2 (lowers pH) & productivity at the surface