OpenStem

@openstem · Joined Jul 2026

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Flashcards9 cards

In one sentence, how does the greenhouse effect actually warm the Earth?1 / 9

Greenhouse gases let incoming shortwave sunlight pass through to warm the surface, but absorb and re-radiate the outgoing longwave (infrared) radiation the surface emits — trapping some of that energy instead of letting it escape straight to space.

Environmental

Environmental · L3 · Climate Feedback Loops

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Flashcards9 cards

What is capacity factor, in one sentence?1 / 9

The ratio of the energy a power plant actually produces over a period to the maximum energy it could produce if it ran at full rated ('nameplate') output the whole time.

Environmental

Environmental · L3 · Renewable Energy Technologies

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Flashcards9 cards

What's the key difference between PM2.5 and PM10 particulate matter?1 / 9

PM10 is particulate matter up to 10 micrometres across — visible dust, pollen, mould spores. PM2.5 is finer, up to 2.5 micrometres — small enough to penetrate deep into the lungs and even cross into the bloodstream, making it more hazardous to health at the same mass concentration.

Environmental

Environmental · L3 · Air Quality Index & Pollutants

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What is eutrophication?1 / 9

The process by which a body of water becomes excessively enriched with nutrients — mainly nitrogen and phosphorus — triggering excessive plant and algae growth that ultimately degrades water quality.

Environmental

Environmental · L3 · Water Quality & Eutrophication

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What was the Kyoto Protocol (1997), and what was its central structure?1 / 9

An international treaty under the UN that set legally binding greenhouse-gas emission-reduction targets — but only for developed ('Annex I') countries. Developing nations had no binding targets, and the United States never ratified it.

Environmental

Environmental · L3 · Environmental Policy & International Agreements

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What is ecological succession?1 / 9

The gradual, predictable process by which the species composition of an ecosystem changes over time, typically progressing toward a more stable, complex community.

Environmental

Environmental · L3 · Ecological Succession

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What is the Brundtland Commission's definition of sustainable development?1 / 9

"Development that meets the needs of the present without compromising the ability of future generations to meet their own needs" — from the 1987 UN report Our Common Future.

Environmental

Environmental · L3 · Sustainable Development & the Triple Bottom Line

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What two criteria does a region need to meet to qualify as a 'biodiversity hotspot' under Conservation International's definition?1 / 9

It must contain at least 1,500 endemic vascular plant species — found nowhere else on Earth — AND have already lost at least 70% of its original natural habitat.

Environmental

Environmental · L3 · Biodiversity Hotspots & Extinction Rates

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What is a 'linear economy,' in the take-make-dispose sense?1 / 9

An economic model where raw materials are extracted, made into products, used, and then thrown away as waste — resources flow in one direction and are not recovered.

Environmental

Environmental · L3 · Waste Management & the Circular Economy

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What is glacier mass balance?1 / 9

The net difference between how much ice/snow a glacier gains (accumulation) and loses (ablation) over a year, usually expressed in metres of water equivalent. A positive balance means the glacier is growing; a negative balance means it's shrinking.

Environmental

Environmental · L3 · Glacial Mass Balance & Sea-Level Contribution

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What is ocean acidification, in one sentence?1 / 9

The ongoing decrease in ocean pH caused by seawater absorbing excess atmospheric CO₂, which reacts with water to form carbonic acid.

Environmental

Environmental · L3 · Ocean Acidification

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What is the symbiotic relationship at the heart of a healthy coral, and what does it provide?1 / 9

Coral polyps host zooxanthellae — photosynthetic algae living in their tissue. The algae photosynthesise and supply the coral with up to about 90% of its energy, while also giving the coral its vivid colour; in return, the coral provides shelter and compounds the algae need.

Environmental

Environmental · L3 · Coral Bleaching Mechanism

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Why do wetland soils decompose organic matter so much more slowly than dry upland soils?1 / 9

Wetland soils are waterlogged, which blocks oxygen from diffusing in. Most efficient decomposition needs oxygen (aerobic respiration), so in these anaerobic conditions dead plant material breaks down far more slowly than it accumulates.

Environmental

Environmental · L3 · Wetlands as Carbon Sinks & Nutrient Filters

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What is an aquifer?1 / 10

An underground layer of permeable rock or sediment (like sand or gravel) that can store and transmit significant amounts of water — essentially a natural underground reservoir.

Environmental

Environmental · L3 · Groundwater Hydrology

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What is the urban heat island (UHI) effect?1 / 9

The tendency of cities to be measurably warmer than their surrounding rural areas, driven by how urban surfaces and structures absorb, retain, and generate heat differently than natural land cover.

Environmental

Environmental · L3 · Urban Heat Island: Quantitative Drivers & Mitigation

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What is a life-cycle assessment (LCA)?1 / 9

A systematic method for evaluating the total environmental impact of a product or material across its entire life — from raw material extraction through manufacturing, use, and disposal — rather than looking at just one stage in isolation.

Environmental

Environmental · L3 · Life-Cycle Assessment (LCA)

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What is an environmental impact assessment (EIA)?1 / 10

A formal, structured process used to predict and evaluate the likely environmental consequences of a proposed project — such as a mine, dam, or highway — before it's approved, so that impacts can be avoided, reduced, or mitigated in advance.

Environmental

Environmental · L3 · Environmental Impact Assessment (EIA)

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What is an ecological footprint?1 / 9

A measure of how much biologically productive land and water area a person, city, or country requires to produce the resources it consumes and absorb the waste (especially CO₂) it generates.

Environmental

Environmental · L3 · Ecological Footprint & Biocapacity

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What is bioaccumulation?1 / 9

The build-up of a substance — often a toxin like mercury or a pesticide like DDT — in an individual organism's tissue, occurring when the organism absorbs or ingests the substance faster than its body can metabolise or excrete it.

Environmental

Environmental · L3 · Bioaccumulation & Biomagnification

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What is remote sensing, in the context of environmental monitoring?1 / 9

Collecting information about Earth's surface or atmosphere from a distance — typically using instruments on satellites or aircraft — without direct physical contact with the area being studied.

Environmental

Environmental · L3 · Environmental Monitoring & Remote Sensing

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What is a GCM (General Circulation Model / Global Climate Model), conceptually?1 / 9

A computer simulation that divides the atmosphere and ocean into a 3D grid of cells and, for each cell, solves physical equations governing fluid motion, heat transfer, and radiation, stepping forward in time to project how the climate system evolves.

Environmental

Environmental · L3 · Climate Models & Scenario Projections

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What is potential evapotranspiration (PET)?1 / 9

The amount of water that would evaporate from soil and transpire from plants in a given location if water supply were unlimited — essentially the atmosphere's 'demand' for water, driven mainly by temperature, sunlight, humidity, and wind.

Environmental

Environmental · L3 · Desert Ecosystems: Water Balance & Adaptations

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Flashcards11 cards

What are the three types of tectonic plate boundaries?1 / 11

Divergent boundaries: plates move apart; new oceanic crust forms at mid-ocean ridges (e.g. Mid-Atlantic Ridge). Convergent boundaries: plates collide; one may subduct beneath the other (ocean-ocean or ocean-continent) or form mountain ranges (continent-continent, e.g. Himalayas). Transform boundaries: plates slide horizontally past each other; produces earthquakes (e.g. San Andreas Fault).

Environmental

Environmental · L4 · Plate Tectonics & Earth's Interior

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What is a mineral and what are the five criteria for classification?1 / 11

A mineral is a naturally occurring, inorganic, solid substance with a definite chemical composition and an ordered crystalline structure. The five criteria: (1) Naturally occurring — formed by geological processes. (2) Inorganic — not produced by living organisms. (3) Solid — crystalline at normal conditions. (4) Definite chemical composition — can be expressed by a formula (e.g. quartz: SiO₂). (5) Ordered internal structure — atoms arranged in a repeating lattice.

Environmental

Environmental · L4 · Minerals, Rocks & the Rock Cycle

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What are the main layers of Earth's atmosphere in order from the surface?1 / 10

Troposphere (0–12 km): contains 75% of atmospheric mass and all weather; temperature decreases with altitude (~6.5 °C/km lapse rate). Stratosphere (12–50 km): temperature increases with altitude due to ozone absorption of UV; location of the ozone layer. Mesosphere (50–80 km): temperature decreases again; meteors burn up here. Thermosphere (80–600+ km): temperature rises dramatically; very low density; aurora borealis/australis form here. Exosphere: outermost fringe, merging with interplanetary space.

Environmental

Environmental · L4 · Atmosphere, Weather & Climate Systems

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What enzyme catalyses biological nitrogen fixation, and what is its ATP cost?1 / 9

Nitrogenase, a two-component metalloenzyme (Fe protein + MoFe protein) found in diazotrophs such as Rhizobium and free-living Azotobacter. It reduces N₂ to ammonia at enormous energetic cost — roughly 16 ATP are hydrolysed per N₂ fixed — which is why the reaction is confined to specialised, oxygen-protected cells (e.g. root nodules, or heterocysts in cyanobacteria, since nitrogenase is irreversibly inactivated by O₂).

Environmental

Environmental · L4 · Environmental Microbiology

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What does CLORPT stand for, and what does it describe?1 / 9

CLORPT is the mnemonic for the five factors that control soil formation, first formalised by Hans Jenny (1941): Climate, Organisms, Relief (topography), Parent material, and Time. Any two soils that differ do so because at least one of these five factors differed during their development.

Environmental

Environmental · L4 · Soil Science (Pedology)

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State the watershed water balance equation and define each term.1 / 9

P = ET + Q + ΔS, where P is precipitation input, ET is evapotranspiration (evaporation + plant transpiration), Q is runoff (streamflow leaving the watershed), and ΔS is the change in water storage (soil moisture, groundwater, surface water) over the period considered. Over a long enough averaging period, ΔS trends toward zero and P ≈ ET + Q.

Environmental

Environmental · L4 · Quantitative Hydrology

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What is the NO2 photolysis cycle, and why does it alone NOT cause ozone to accumulate?1 / 8

NO₂ absorbs sunlight and splits: NO₂ + hν → NO + O. The freed oxygen atom combines with O₂ (plus a third body M to absorb excess energy) to form ozone: O + O₂ + M → O₃ + M. But ozone then reacts with the NO just produced: O₃ + NO → NO₂ + O₂, regenerating the starting NO₂. This closed loop is the photostationary state — a 'null cycle' that constantly interconverts NOx and O3 without net ozone buildup.

Environmental

Environmental · L4 · Atmospheric Chemistry

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What is LD50, and how is it determined experimentally?1 / 8

LD50 (lethal dose, 50%) is the dose of a substance that kills 50% of a test population under specified exposure conditions, usually expressed in mg substance per kg body weight. It's determined by exposing groups of test organisms to a range of doses and fitting a dose-response curve to find the dose at which mortality crosses the 50% mark. A LOWER LD50 means a MORE toxic substance.

Environmental

Environmental · L4 · Environmental Toxicology

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