OpenStem

@openstem · Joined Jul 2026

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Flashcards8 cards

What is a spectral band, and why do Earth-observing satellites capture more bands than just visible light?1 / 8

A spectral band is a specific range of wavelengths a sensor measures separately (e.g. blue, green, red, near-infrared). Satellites capture bands beyond the visible (especially near-infrared and shortwave-infrared) because different surface materials — healthy vegetation, water, bare soil, urban surfaces — reflect and absorb very differently outside the visible range, letting analysts distinguish land-cover types that look nearly identical to the human eye.

Environmental

Environmental · L4 · Remote Sensing & GIS

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Flashcards8 cards

What is NEPA (1970), and what must it require of federal agencies before a major action?1 / 8

The National Environmental Policy Act requires U.S. federal agencies to assess the environmental effects of proposed 'major federal actions significantly affecting the quality of the human environment' BEFORE undertaking them. It's a procedural law — it doesn't dictate a specific outcome, but forces agencies to document and disclose environmental consequences and consider alternatives before deciding.

Environmental

Environmental · L4 · Environmental Law & Regulation

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Flashcards8 cards

What is industrial ecology, and what natural system does it use as its central metaphor?1 / 8

Industrial ecology studies industrial systems as though they were ecosystems — tracking material and energy flows the way ecologists track nutrient cycles, and looking for ways one facility's waste output can become another's raw material input, mimicking how natural ecosystems recycle nutrients with essentially zero waste.

Environmental

Environmental · L4 · Industrial Ecology & Life-Cycle Thinking

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What is a negative externality, and give an environmental example.1 / 8

A negative externality occurs when a market transaction imposes an uncompensated cost on a third party not involved in that transaction. Example: a factory's pollution harms downwind residents' health and downstream water users, but neither the factory nor its customers pay for that harm — it's a cost the market price never reflects, leading to over-production relative to the socially optimal level.

Environmental

Environmental · L4 · Environmental Economics

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What attributes does the Society for Ecological Restoration (SER) use to define a 'restored' ecosystem?1 / 8

SER's core attributes include: characteristic species composition and community structure resembling the reference system, ecological processes functioning normally (nutrient cycling, energy flow), resilience to normal periodic stress, and — critically — the ability to sustain itself with minimal further intervention. A site isn't 'restored' just because it looks green again; it must be functionally self-sustaining.

Environmental

Environmental · L4 · Restoration Ecology

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Flashcards8 cards

What are the three main stages of wastewater treatment, and what does each broadly remove?1 / 8

Primary treatment: physical processes (screening, grit removal, sedimentation) remove large debris and settleable/floatable solids. Secondary treatment: biological processes (activated sludge, trickling filters) use microorganisms to break down dissolved and colloidal organic matter. Tertiary treatment: advanced physical/chemical processes remove remaining nutrients (nitrogen, phosphorus), fine solids, and pathogens before discharge.

Environmental

Environmental · L4 · Wastewater Treatment Engineering

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What is a wet scrubber, and how does a limestone slurry scrubber remove SO2 from flue gas?1 / 8

A wet scrubber contacts flue gas with a liquid (often a limestone/water slurry) to dissolve or react out acid gases. For SO2: SO2 gas dissolves into the slurry and reacts with the limestone (CaCO3), ultimately forming solid calcium sulfate (gypsum, CaSO4) — this flue-gas desulfurization (FGD) reaction removes over 90% of SO2 in modern coal plants, and the gypsum byproduct is often sold commercially (e.g. to wallboard manufacturers).

Environmental

Environmental · L4 · Air Pollution Control Engineering

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What is a General Circulation Model (GCM), and what components does it couple?1 / 8

A GCM is a numerical model that solves the physical equations governing fluid motion, radiation, and thermodynamics on a three-dimensional grid spanning the globe, projecting how the climate system evolves over time. Modern GCMs are usually 'coupled' — they simultaneously simulate the atmosphere, ocean, land surface, and sea ice/ice sheets, and the exchanges of heat, moisture, and momentum between them, rather than modelling the atmosphere in isolation.

Environmental

Environmental · L4 · Climate Modeling

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Flashcards8 cards

Define Minimum Viable Population (MVP).1 / 8

MVP is the smallest population size estimated to have a specified probability (e.g. 95%) of persisting for a specified period (e.g. 100 years), accounting for demographic, environmental, and genetic stochasticity plus catastrophic events. It is a probabilistic threshold, not a single fixed number — MVP estimates vary by species life history and the risk tolerance chosen.

Environmental

Environmental · L4 · Conservation Biology & Population Viability

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Flashcards8 cards

Why is sound intensity measured on a logarithmic decibel scale rather than a linear one?1 / 8

Human hearing spans an enormous intensity range — roughly 12 orders of magnitude from the threshold of hearing to the threshold of pain — and perceived loudness itself scales roughly logarithmically with physical intensity. A logarithmic decibel scale (referenced to I0, the threshold of hearing) compresses that huge range into a manageable 0-140 dB scale that also better matches subjective loudness perception.

Environmental

Environmental · L4 · Environmental Acoustics & Noise Pollution

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Flashcards8 cards

Name and briefly describe the USEPA's four-step human health risk assessment paradigm.1 / 8

(1) Hazard identification — does the chemical cause an adverse effect, and in whom? (2) Dose-response assessment — how does the magnitude of exposure relate to the probability/severity of the effect? (3) Exposure assessment — how much of the chemical do people actually contact, via which pathways? (4) Risk characterization — combining dose-response and exposure information into a quantitative estimate of risk, with its uncertainties.

Environmental

Environmental · L4 · Human Health Risk Assessment

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Flashcards8 cards

Define Integrated Water Resources Management (IWRM) and its three commonly cited pillars.1 / 8

IWRM (per the Global Water Partnership) is a process promoting coordinated development and management of water, land, and related resources to maximize resulting economic and social welfare equitably, without compromising the sustainability of vital ecosystems. Its three pillars are economic efficiency (using water productively), social equity (fair access across users, including marginalized groups), and environmental sustainability (protecting ecosystem water needs).

Environmental

Environmental · L4 · Integrated Water Resources Management

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Define capacity factor and write its formula.1 / 8

Capacity factor is the ratio of a generator's actual output over a period to what it would have produced running at full rated capacity the entire time. It captures intermittency and downtime: utility-scale solar PV typically runs ~20-25% CF, onshore wind ~35-45%, and nuclear ~90%+, reflecting how consistently each source can actually generate relative to its nameplate rating.

Environmental

Environmental · L4 · Renewable Energy Systems Engineering

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How does a modern sanitary landfill differ from an open dump?1 / 8

A sanitary landfill engineers containment: a composite liner (compacted clay plus an HDPE geomembrane) beneath the waste stops leachate from reaching groundwater, a leachate collection system pipes percolate to treatment, daily soil (or alternative) cover controls odor/vectors/blowing litter, and landfill gas is actively collected. An open dump has none of these controls — waste is simply deposited on the ground with no liner, no leachate management, and no gas capture.

Environmental

Environmental · L4 · Solid Waste Management Engineering

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Flashcards8 cards

What is Environmental Impact Assessment (EIA), and what decision does it feed into?1 / 8

EIA is a structured process for predicting, evaluating, and disclosing the likely environmental effects of a proposed project (a highway, mine, dam, factory) BEFORE a permitting decision is made. It doesn't itself approve or reject a project — it produces the evidence base (an Environmental Impact Statement or Report) that regulators, and often the public, use to decide whether the project proceeds, proceeds with conditions, or is denied.

Environmental

Environmental · L4 · Environmental Impact Assessment

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Flashcards4 cards

Describe the carbonate chemistry of ocean acidification and its impact on the calcium carbonate saturation state.1 / 4

Anthropogenic CO₂ dissolves in seawater following the equilibria:

Environmental

Environmental · L5 · Ocean Acidification, Radiative Forcing, and Plate Geodesy

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Flashcards4 cards

Write the rotating-frame momentum equation for an inviscid fluid, including the Coriolis term.1 / 4

In a frame rotating at angular velocity Ω, the momentum equation per unit mass is:

Environmental

Environmental · L5 · Geophysical Fluid Dynamics

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Flashcards8 cards

What is a 'box model' (reservoir model) in biogeochemistry, and what are its two core components?1 / 8

A box model represents a biogeochemical cycle as discrete reservoirs (boxes) — e.g. atmosphere, surface ocean, deep ocean, terrestrial biosphere — each holding a mass M_i of a substance (carbon, nitrogen, phosphorus), connected by fluxes F_ij that transfer mass between reservoir i and reservoir j. The modeler's job is to specify each flux as a function of reservoir state, then integrate the resulting system of ordinary differential equations forward in time.

Environmental

Environmental · L5 · Quantitative Biogeochemical Cycle Modeling

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Flashcards8 cards

Define the delta (δ) notation used for stable-isotope ratios, in general form.1 / 8

R is the ratio of the rare to common isotope (e.g. ¹⁸O/¹⁶O, ¹³C/¹²C, ²H/¹H). δ is reported in per mil (‰) relative to an international standard — VSMOW for oxygen/hydrogen in water, VPDB for carbon in carbonates.

Environmental

Environmental · L5 · Paleoclimate Proxies & Isotope Geochemistry

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Flashcards8 cards

State the Beer–Lambert law for monochromatic radiation passing through an absorbing medium.1 / 8

Radiation intensity I decays exponentially with optical depth τ traversed. I₀ is the incident intensity; τ integrates the absorber's extinction along the path.

Environmental

Environmental · L5 · Atmospheric Radiative Transfer

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Flashcards8 cards

Define a metapopulation.1 / 8

A metapopulation is a 'population of populations' — a set of spatially discrete local populations occupying separate habitat patches, connected (or not) by occasional dispersal between patches, where any single local population may go extinct and be recolonized independently.

Environmental

Environmental · L5 · Landscape Ecology & Metapopulation Dynamics

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Flashcards8 cards

Why is fitting an ordinary least-squares (OLS) trend line directly to a climate time series statistically risky?1 / 8

OLS standard errors assume independent, identically distributed residuals. Climate time series are almost always serially (auto-)correlated — today's anomaly is correlated with yesterday's/last year's — which violates that assumption. Ignoring autocorrelation makes the OLS trend's standard error too small, so a trend can appear 'statistically significant' when it is really within the range of natural short-term persistence.

Environmental

Environmental · L5 · Environmental Statistics: Trend Detection

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Flashcards8 cards

Write the linearized global energy-balance equation defining the climate feedback parameter λ.1 / 8

ΔN is the top-of-atmosphere radiative imbalance, ΔF the applied forcing, ΔT the global mean surface temperature response, and λ (W/m²/K) the net climate feedback parameter. At equilibrium ΔN = 0, so ΔT_eq = ΔF/λ.

Environmental

Environmental · L5 · Earth System Feedback Quantification

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Flashcards8 cards

Write the Richards equation for 1-D vertical unsaturated (variably saturated) flow.1 / 8

θ is volumetric water content, ψ the matric (suction) pressure head, K(θ) the unsaturated hydraulic conductivity (a strongly nonlinear function of θ), z depth (positive downward), t time. It's the governing PDE for infiltration and drainage through the unsaturated soil zone.

Environmental

Environmental · L5 · Hydrological Modeling

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Flashcards8 cards

Define LC50 and EC50 in toxicology, and how do they differ?1 / 8

LC50 (lethal concentration, 50%) is the concentration of a substance that causes death in 50% of a test population over a specified exposure duration. EC50 (effective concentration, 50%) is broader — the concentration producing any defined sub-lethal effect (e.g. reduced growth, reproductive impairment) in 50% of the population. LC50 is a special case of EC50 where the 'effect' is mortality.

Environmental

Environmental · L5 · Quantitative Ecotoxicology

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What is 'top-of-atmosphere' (TOA) radiance, and why must it be corrected before land-surface analysis?1 / 8

TOA radiance is what a satellite sensor actually measures — surface-reflected sunlight after it has already passed through the atmosphere twice (down and back up), plus atmospheric scattering and emission contributions along the way. Because the atmosphere scatters and absorbs light wavelength-dependently (aerosols, water vapor, ozone), TOA radiance is a distorted version of true surface reflectance and must be corrected before it can be used quantitatively for land-surface science.

Environmental

Environmental · L5 · Remote Sensing Retrieval & Inversion Algorithms

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Flashcards8 cards

What is an Integrated Assessment Model (IAM), and what three sub-modules does it typically couple?1 / 8

An IAM couples a simplified representation of the economy (an emissions/growth module), a simplified climate model (converting emissions to concentrations to temperature), and a damage function (converting temperature change back into economic loss) into one framework — letting researchers explore how emissions pathways, climate response, and economic costs interact under different policy scenarios.

Environmental

Environmental · L5 · Advanced Environmental Policy Analysis

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Flashcards8 cards

State Glen's flow law for the deformation (creep) of glacial ice.1 / 8

The strain rate ε̇ of ice deforming under shear stress τ follows a power law, with flow-law exponent n ≈ 3 (empirically, for typical glacier stress ranges) and rate factor A, which is strongly temperature-dependent (warmer ice flows much faster for the same stress). This nonlinear rheology — not simple Newtonian viscosity — is why ice deformation accelerates sharply near the pressure-melting point.

Environmental

Environmental · L5 · Glaciology & Ice Sheet Dynamics

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Flashcards8 cards

What is the atmospheric boundary layer (ABL), and why is turbulence its dominant transport mechanism?1 / 8

The ABL is the lowest ~100 m to ~2 km of the atmosphere, directly influenced by the surface on timescales of an hour or less (via friction, heating, and moisture exchange). Molecular diffusion is far too slow to transport heat, momentum, and moisture through this layer at observed rates — instead, turbulent eddies (chaotic swirling motions spanning millimetres to kilometres) dominate vertical transport, orders of magnitude faster than molecular diffusion alone.

Environmental

Environmental · L5 · Atmospheric Boundary Layer Physics

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Flashcards8 cards

State the Global Meteoric Water Line (GMWL) equation and what it describes.1 / 8

The GMWL (Craig, 1961) is the global-average linear relationship between δ²H and δ¹⁸O in precipitation, arising because both isotopes fractionate together during evaporation and condensation, with a well-established ratio between their fractionation factors. The slope of 8 reflects equilibrium fractionation; the intercept of 10 (the 'deuterium excess' baseline) reflects kinetic fractionation during evaporation from the ocean surface under typical humidity conditions.

Environmental

Environmental · L5 · Isotope Hydrology & Water Tracing

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