New Zealand Scholarship Earth and Space Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Residence time

The average time a substance spends in a reservoir, calculated as reservoir mass divided by the flux through it; key for comparing fast atmospheric and slow geological carbon reservoirs.

Ice-albedo feedback

A positive feedback in which warming melts reflective ice, exposing darker land or ocean, which absorbs more solar energy and drives further warming.

Negative feedback

A process that counteracts a perturbation and stabilises a system, such as increased silicate weathering removing atmospheric carbon dioxide as temperatures rise.

Latent heat of vaporisation

Energy absorbed when water evaporates and released when it condenses, roughly 2.26 million joules per kilogram, linking ocean, atmosphere and weather systems.

Tipping element

A subsystem that crosses a threshold and shifts abruptly to a different state, often with limited reversibility, such as ice-sheet collapse or Amazon dieback.

Slab pull

The dominant plate-driving force: dense, cold subducting lithosphere sinks into the mantle and pulls the trailing plate along with it.

Bowen's reaction series

The sequence in which silicate minerals crystallise from cooling magma, from mafic olivine and pyroxene to felsic quartz and potassium feldspar.

Isostasy

Gravitational balance in which rigid lithosphere floats on the denser mantle; mountain roots and post-glacial rebound reflect crustal density and thickness contrasts.

Porphyritic texture

An igneous texture with large crystals set in a finer groundmass, recording two cooling stages: slow crystallisation at depth followed by rapid cooling near the surface.

Benioff-Wadati zone

A dipping zone of earthquake foci extending to about 700 kilometres depth, marking the cold, brittle interior of a subducting oceanic slab.

Index mineral

A metamorphic mineral whose first appearance marks a specific pressure-temperature condition, such as garnet or kyanite, used to map metamorphic grade.

Principle of superposition

In an undisturbed sequence of sedimentary rocks, each layer is younger than the one below it and older than the one above it.

Radiometric decay law

Radioactive atoms decay as N equals N0 times e to the minus lambda t, where lambda equals ln2 divided by the half-life, giving ages if the system stayed closed.

Index fossil

A fossil species that is geographically widespread, abundant and short-lived in time, allowing correlation of rock layers across distant regions.

Great Oxidation Event

A rise in atmospheric oxygen about 2.4 billion years ago, recorded by banded iron formations ending and red beds and oxidised minerals appearing.

K-Pg boundary

The roughly 66-million-year-old layer marking the end-Cretaceous extinction, recognised worldwide by an iridium anomaly and shocked quartz from the Chicxulub impact.

Kepler's third law

The square of an orbital period is proportional to the cube of the semi-major axis for bodies orbiting the same mass, allowing mass estimates from orbital data.

Main-sequence lifetime

The time a star fuses hydrogen in its core, scaling roughly as stellar mass to the power minus 2.5 relative to the Sun's ten-billion-year lifetime.

Transit method

Detecting an exoplanet by the periodic dimming of its host star as the planet crosses the stellar disc, which yields the planet's radius.

Hubble's law

Distant galaxies recede at speeds proportional to distance, v equals H0 times d, with H0 near 70 kilometres per second per megaparsec; evidence for cosmic expansion.

CNO cycle

A hydrogen-fusion pathway using carbon, nitrogen and oxygen as catalysts, dominant over the proton-proton chain in stars more massive than about 1.3 solar masses.

Coriolis parameter

Twice Earth's angular velocity times the sine of latitude, f equals 2 Omega sin phi; it vanishes at the equator and sets geostrophic current and wind speeds.

Thermohaline circulation

Global deep-ocean overturning driven by density differences from temperature and salinity, including sinking of cold North Atlantic Deep Water and slow upwelling elsewhere.

Ekman transport

Net water transport set 90 degrees to the right of the wind in the Northern Hemisphere, driving coastal upwelling where winds blow parallel to the coast.

Ocean acidification

Uptake of carbon dioxide lowers seawater pH and carbonate saturation, because dissolved CO2 forms carbonic acid that releases hydrogen and bicarbonate ions.

Dry adiabatic lapse rate

The rate at which an unsaturated rising air parcel cools, about 9.8 degrees Celsius per kilometre, compared with roughly 6 for saturated air.

El Nino-Southern Oscillation

An irregular Pacific coupled ocean-atmosphere cycle; El Nino brings weakened trade winds and warm eastern Pacific water, La Nina the opposite, shifting global rainfall.

Precision versus accuracy

Precision is the repeatability of measurements, while accuracy is closeness to the true value; random errors reduce precision and systematic errors reduce accuracy.

p-value

The probability of obtaining data at least as extreme as observed if the null hypothesis were true; it is not the probability that the hypothesis is correct.

Proxy calibration

Matching a climate or environmental proxy against instrumental records over an overlap period, so past values can be reconstructed within the calibrated range.

Snowball Earth

A hypothesis that ice albedo feedback drove near-global glaciation, supported by low-palaeolatitude glacial deposits and cap carbonates above them.

Equilibrium temperature

The temperature at which a body radiates as much energy as it absorbs, set by stellar flux, distance, albedo and any greenhouse warming of the surface.