Earth Systems, Atmospheric Circulation, and Biogeochemical Cycles

Comprehensive vocabulary flashcards covering atmospheric circulation, El Niño-Southern Oscillation (ENSO), the carbon cycle, plate tectonics, seismic structure, and global biogeochemical nutrient cycles.

El Niño Atmospheric Pattern

An ocean-atmosphere phenomenon in which the Pacific Jet stream moves south and spreads further east, bringing wetter winters to the Southern United States and warmer, drier conditions to the North.

La Niña Atmospheric Pattern

An ocean-atmosphere phenomenon causing the polar jet stream to shift northward and weaken over the eastern Pacific, resulting in warmer, drier winters across the Southern United States and wetter, cooler conditions in Canada and the Northern United States.

Coriolis Effect

The deflection of moving air and water caused by Earth's spherical shape and faster rotation at the equator than at the poles, deflecting flows to the right (clockwise) in the Northern Hemisphere and to the left (counterclockwise) in the Southern Hemisphere.

Intertropical Convergence Zone (ITCZ)

The rising branch of the Hadley cell located near the equator, visibly characterized by persistent thunderstorm activity, low surface pressure, and strong convective uplift driven by intense solar insolation.

Hadley Cell

A large-scale atmospheric circulation cell where air rises at the equator, spreads poleward at the tropopause ($12\text{--}16\,\text{km}$), deflects into a west-to-east jet, and subsides around $30^\circ\,\text{N}$ and $30^\circ\,\text{S}$, producing major subtropical desert belts.

Gyre

A large circular surface current system in the subtropical oceans that circulates clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Trade Winds

Permanent east-to-west prevailing winds (easterlies) flowing through Earth's equatorial region.

Westerlies

Prevailing winds flowing from west to east in the middle latitudes between $30^\circ$ and $60^\circ$, originating from high-pressure zones in the horse latitudes (~$30^\circ$) and trending toward the poles.

Ekman Transport

The net movement of a fluid layer driven by wind friction and the Coriolis effect, directing water approximately $90^\circ$ to the right of the wind in the Northern Hemisphere and $90^\circ$ to the left in the Southern Hemisphere.

Thermohaline Circulation

Deep-ocean circulation driven by differences in water density that transports large amounts of heat from the equator toward the poles, keeping regions such as Britain and Northern Europe unusually mild.

Upwelling Zones

Coastal or oceanic regions where cold, nutrient-rich subsurface water rises to replace surface water pushed offshore by wind-driven Ekman transport, fueling phytoplankton blooms and productive fisheries.

California Current

A cold surface ocean current flowing southward along the western coast of the United States and Mexico, representing the eastern limb of the North Pacific Gyre and driving coastal upwelling.

Peru (Humboldt) Current

A cold surface current flowing northward along the west coast of South America as the eastern limb of the South Pacific Gyre, driving strong coastal upwelling that is suppressed during El Niño.

Radiocarbon Decay Curve

A graphical representation of radioactive decay showing the exponential decrease of remaining parent isotope ($X$) by half during each successive half-life as it converts into daughter isotope ($Y$).

Walker Circulation

A zonal (east-west) atmospheric overturning cell along the equatorial Pacific driven by sea surface temperature gradients between the warm western Pacific pool (~$29\text{--}30\,^\circ\text{C}$) and the cool eastern Pacific upwelling cold tongue.

Bjerknes Feedback Loop

A coupled positive feedback mechanism between ocean temperatures and atmospheric winds in which sea-surface temperature anomalies weaken or strengthen trade winds, which in turn amplify and sustain the ENSO phase.

Kelvin Waves

Fast-moving eastward oceanic waves along the equator that act as a delayed oscillator negative feedback, flattening the thermocline to help terminate an ENSO event.

Subsurface Depletion

A negative feedback condition where poleward warm water volume discharge removes heat from the equator until the equatorial Pacific runs out of warm water, arresting El Niño warming.

Thermodynamic Damping

A negative feedback mechanism in which increased latent heat flux (evaporation) and cloud cover block solar insolation, causing the ocean to lose heat faster than the Bjerknes feedback can amplify it.

Biological Pump

The marine process converting dissolved inorganic $\text{CO}_2$ into organic matter via phytoplankton photosynthesis in the photic zone, followed by particle sinking, bacterial remineralization, and net sediment burial.

Global Carbon Reservoirs

The distribution of stored carbon across the Earth system, dominated on geological timescales by sedimentary limestone ($40{,}000{,}000\,\text{Gt(C)}$) and organic carbon in sedimentary rocks ($10{,}000{,}000\,\text{Gt(C)}$).

Earth Interior Seismic Layers

The internal structure of Earth determined by seismic velocities, showing that compressional P waves travel through both solid and liquid layers, whereas shear S waves cannot penetrate the liquid outer core.

Mid-Ocean Ridge Volcanism

Divergent boundary volcanism characterized by low-silica, low-gas basaltic magma that flows easily and erupts quietly to form broad shield volcanoes or oceanic plateaus.

Subduction Zone Volcanism

Convergent boundary volcanism characterized by viscous, high-silica and high-gas andesitic or rhyolitic magma that erupts explosively to build steep composite stratovolcanoes.

Mid-Atlantic Ridge

A slow-spreading divergent boundary stretching about $16{,}000\,\text{km}$ from the Arctic Ocean to Antarctica, with a crest depth of ~$2{,}500\,\text{m}$ and a spreading rate of roughly $25\,\text{mm/yr}$.

East African Rift System

A continental divergent plate boundary extending $3{,}000\text{--}4{,}000\,\text{km}$ from the Afar Triple Junction to Mozambique, where the African Plate separates from the Somali Plate at $6\text{--}9\,\text{mm/yr}$.

Huyara

A traditional charcoal-fired, wind-drafted clay kiln used for smelting silver ores at Cerro Rico de Potosí using soroche ($\text{Pb, AgS}$) as a flux.

Total Lead ($\text{Pb}$)

A cornerstone pollution indicator in sedimentary records that remains relatively immobile and reflects historical metallurgical smelting activities.

Anthropocene

The current geological epoch characterized by human activity being the dominant influence on Earth's climate, biogeochemical cycles, and ecosystems.

Paleomagnetism

The study of ancient magnetic fields preserved in archaeological materials, sediments, or rock units, particularly through the alignment of magnetite ($\text{Fe}_3\text{O}_4$) in ocean floor basalts.

BLAG Hypothesis

The hypothesis proposing that seafloor spreading rates regulate global volcanic outgassing of $\text{CO}_2$, acting as the primary long-term tectonic control on atmospheric greenhouse gas levels.

Uplift Weathering Hypothesis

The hypothesis that mountain building actively drives long-term climate cooling by exposing fresh, easily erodible mineral surfaces to enhanced chemical weathering.

Carbonate Weathering

The chemical breakdown of limestone rocks by carbonic acid in rainwater according to the reaction: $\text{CaCO}_3 + \text{H}_2\text{CO}_3 \rightarrow \text{Ca}^{2+} + 2\text{HCO}_3^-$.

Silicate Weathering

The chemical breakdown of silicate rocks that draws down atmospheric carbon via the reaction: $\text{CaSiO}_3 + 2\text{H}_2\text{CO}_3 \rightarrow \text{Ca}^{2+} + 2\text{HCO}_3^- + \text{SiO}_2 + \text{H}_2\text{O}$.

Haber-Bosch Process

An industrial chemical method that synthesizes bioavailable ammonia ($\text{NH}_3$) directly from unreactive atmospheric nitrogen gas ($\text{N}_2$) to produce synthetic fertilizers.

Nitrogen Cycle

The biogeochemical cycle that converts unreactive atmospheric $\text{N}_2$ into reactive ionic forms ($\text{NH}_3$, $\text{NH}_4^+$, $\text{NO}_2^-$, $\text{NO}_3^-$) through bacterial fixation and nitrification before returning it via denitrification.

Eutrophication

The nutrient enrichment of aquatic systems by nitrogen and phosphorus runoff, stimulating algal blooms whose subsequent decomposition severely depletes dissolved oxygen and forms hypoxic dead zones.

Nitrous Oxide ($\text{N}_2\text{O}$)

A potent greenhouse gas emitted by soil microbes during the nitrogen cascade that possesses approximately 270 times the warming potential of $\text{CO}_2$ over a 100-year timescale.

Phosphorus Cycle

A slow sedimentary biogeochemical cycle lacking a significant gaseous atmospheric reservoir, moving phosphorus from rock apatite into soils, biological tissues, rivers, and ocean sediments until tectonic uplift returns it.

Phosphate Rock Reserves

Finite geological rock deposits mined for agricultural phosphorus fertilizer, with approximately 70% of known global reserves concentrated in Morocco and Western Sahara.

Legacy Phosphorus

The accumulated surplus of phosphorus remaining in agricultural soils and aquatic sediments from past applications that continues to leach into watersheds over extended timeframes.