OpenStem

@openstem · Joined Jul 2026

7420 public items8 groups

Quiz5 questions

What three sub-modules does an Integrated Assessment Model typically couple?

AOcean circulation, ice dynamics, and seismic hazardBEconomic growth/emissions, a simplified climate model, and a damage functionCOnly economic growth, with no climate or damage componentsDWeather forecasting, agriculture, and demographics only

Environmental

Environmental · L5 · Advanced Environmental Policy Analysis

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Quiz5 questions

Glen's flow law ε̇ = Aτⁿ with n ≈ 3 implies that ice is:

AA Newtonian fluid, with strain rate directly proportional to stressBA strongly shear-thinning (non-Newtonian) fluid — strain rate grows much faster than stressCA rigid solid with no deformation under any stressDIndependent of temperature

Environmental

Environmental · L5 · Glaciology & Ice Sheet Dynamics

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Quiz5 questions

The 'turbulence closure problem' refers to:

AReynolds-averaging generating new unknown turbulent flux terms faster than new equations are gained, requiring an approximate closure schemeBThe impossibility of ever measuring turbulenceCA problem that only occurs above the tropopauseDThe fact that molecular diffusion alone explains all boundary-layer transport

Environmental

Environmental · L5 · Atmospheric Boundary Layer Physics

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Quiz5 questions

The Global Meteoric Water Line, δ²H = 8δ¹⁸O + 10, describes:

AThe relationship between ocean salinity and depthBThe global-average linear relationship between δ²H and δ¹⁸O in precipitation, from coupled equilibrium and kinetic fractionationCThe rate of ice-sheet mass lossDA relationship that applies only to seawater, never to precipitation

Environmental

Environmental · L5 · Isotope Hydrology & Water Tracing

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Quiz6 questions

A correlative SDM fit on occurrence records estimates a species':

AFundamental niche, directly and completelyBRealized niche — the subset of tolerable conditions it actually occupies given biotic constraintsCEltonian niche exclusivelyDDispersal ability

Environmental

Environmental · L5 · Species Distribution Modeling & Niche Theory — 6 Q

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Quiz6 questions

Why do chemical transport models use operator splitting rather than solving the full continuity equation in one coupled step?

ABecause chemistry has no effect on concentrationBEach process (advection, diffusion, chemistry, deposition) needs a different numerical method, and a single fully coupled solve is far more computationally expensiveCOperator splitting eliminates the need for a chemical mechanismDIt is required by the CFL condition specifically

Environmental

Environmental · L5 · Atmospheric Chemistry & Chemical Transport Modeling — 6 Q

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Quiz6 questions

What physical argument justifies the Gaussian shape of a plume's crosswind/vertical concentration profile?

ATurbulent eddies always move air in straight linesBMany small, statistically independent turbulent displacements accumulate into an approximately normal distribution, by a central-limit-theorem-style argumentCGround-level concentration is always zeroDWind speed is constant with height

Environmental

Environmental · L5 · Environmental Fluid Mechanics — 6 Q

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Quiz6 questions

What did May's 1972 analysis show about randomly structured community matrices?

AComplexity (higher S, C, or sigma) always increases stabilityBStability becomes progressively less likely as species richness, connectance, or interaction strength increaseCRandom networks are always stable regardless of sizeDConnectance has no effect on stability

Environmental

Environmental · L5 · Ecological Network Analysis & Food Web Stability — 6 Q

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Quiz6 questions

Why is a case-control design typically preferred for studying a RARE disease?

AIt requires no comparison groupBIt starts from existing cases rather than waiting to accumulate enough cases in a forward-following cohort, making it far faster and cheaperCIt eliminates recall bias entirelyDIt measures exposure before disease onset

Environmental

Environmental · L5 · Environmental Epidemiology — 6 Q

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Quiz6 questions

Why is the true linear pore velocity v always greater than the Darcy flux q?

ADarcy flux is measured in different units entirelyBDarcy flux is averaged over the full cross-sectional area including solid grains, while water only actually flows through the pore fraction (v = q / effective porosity)CPore velocity is always slower than Darcy fluxDThey are actually always equal

Environmental

Environmental · L5 · Groundwater Flow & Contaminant Transport Modeling — 6 Q

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Quiz6 questions

For a near-term (next-decade) regional climate projection, which uncertainty source typically dominates?

AScenario uncertaintyBInternal variabilityCThere is no meaningful uncertainty at short horizonsDModel uncertainty always dominates at every horizon equally

Environmental

Environmental · L5 · Climate Model Uncertainty Quantification & Bayesian Calibration — 6 Q

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Note~300 words · 2 min

Non-Native Isn't Automatically 'Invasive' A species is 'non-native' simply if it now lives somewhere outside the range it evolved in. Most non-native species settle in quietly without causing much disruption. 'Invasive' is a narrower, stric

Environmental

Environmental · L2 · Invasive Species

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Note~367 words · 2 min

Two Kinds of Currents, Two Different Drivers Ocean water is always moving, but the forces behind that motion differ sharply depending on depth. Surface currents, in the upper few hundred meters, are driven mainly by wind dragging across the

Environmental

Environmental · L2 · Ocean Currents & Marine Ecosystems

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Note~178 words · 1 min

Where Is Earth's Fresh Water? About 71% of Earth is covered in water, but almost all of it is salty ocean water. Only about 3% is fresh water, and most of that is locked up in glaciers and ice caps. Less than 1% is available in rivers, lake

Environmental

Environmental · L1 · Fresh Water: Our Most Precious Resource

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Note~143 words · 1 min

The Three R's Every day we use lots of materials — paper, plastic, glass, metal. The 'Three R's' are three ways to make less of that turn into rubbish. Where Does Recycling Go? Should I Reduce, Reuse, or Recycle? Before you toss something o

Environmental

Environmental · L1 · Recycling & the Three R's

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Note~117 words · 1 min

Energy That Never Runs Out Renewable energy comes from natural sources that keep replenishing themselves — the Sun keeps shining, the wind keeps blowing, and rivers keep flowing. From Nature to Your Lightbulb Whichever source is used, the e

Environmental

Environmental · L1 · Renewable & Clean Energy

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Note~446 words · 2 min

Farming That Lasts Sustainable agriculture describes farming practices aimed at producing food without wearing down the soil, water, and biodiversity that future harvests depend on. It's less a single technique than a set of complementary p

Environmental

Environmental · L2 · Sustainable Agriculture

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Note~289 words · 1 min

Building a Glacier from Snowflakes A glacier is essentially decades — or millennia — of unmelted snow, compressed into moving ice. Where annual snowfall consistently outpaces melting, fresh snow buries older layers. The weight above squeeze

Environmental

Environmental · L2 · Glaciers & Ice Sheets

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Note~316 words · 2 min

What Makes a Desert Deserts are defined by scarce precipitation — usually under about 25 centimeters a year — not necessarily by heat. Whatever their temperature, deserts share the same core survival challenge for life: finding and conservi

Environmental

Environmental · L2 · Desert Ecosystems & Adaptations

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Note~109 words · 1 min

What Is a Habitat? A habitat is the natural place where a plant or animal lives. It gives everything a living thing needs: food, water, shelter, and space. Energy Moves Along a Food Chain A food chain shows who eats whom, and how energy fro

Environmental

Environmental · L1 · Animal Habitats & Food Chains

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Note~139 words · 1 min

What Does 'Endangered' Mean? An endangered animal is one with so few individuals left that the entire species is at risk of disappearing. If none are left anywhere, the species is extinct — gone forever. Why Do Animals Become Endangered? Ho

Environmental

Environmental · L1 · Endangered Animals & Conservation

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Note~133 words · 1 min

What Do Forests Give Us? Forests do far more than look nice. They quietly do jobs that keep the whole planet working. What Is Deforestation? Deforestation happens when large areas of forest are cut down — often to clear space for farms, roa

Environmental

Environmental · L1 · Forests & Why Trees Matter

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Note~132 words · 1 min

Life in the Ocean The ocean is home to an enormous number of living things — from tiny plankton to the biggest animal that has ever lived, the blue whale. How Plastic Gets to the Ocean Most ocean plastic does not start in the ocean — it sta

Environmental

Environmental · L1 · Ocean Life & Plastic Pollution

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Note~315 words · 2 min

Land That's Neither Fully Land Nor Fully Water A wetland is any area saturated with water — all year or just seasonally — long enough for hydrophytic (water-adapted) plants and soils to develop. That simple definition covers a surprisingly

Environmental

Environmental · L2 · Wetland Ecosystems

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Note~296 words · 1 min

A Reef Built by Tiny Animals Each coral polyp is a small, soft-bodied animal that secretes a hard skeleton of calcium carbonate around itself. Individually, a polyp is barely visible — but generations of polyps building skeleton on top of s

Environmental

Environmental · L2 · Coral Reef Ecology

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Note~266 words · 1 min

Keeping Heat Where You Want It Insulation slows heat conduction through a building's walls, roof, and floor by trapping air (or another low-conductivity material) that resists heat flow. Its effectiveness is rated by R-value — the higher th

Environmental

Environmental · L2 · Energy Efficiency in Buildings

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Note~132 words · 1 min

What Makes Air Dirty? The air around us is usually invisible, but it can carry tiny bits of smoke, gas, and dust that make it unhealthy to breathe. This is called air pollution. Why Clean Air Matters Every breath we take brings air into our

Environmental

Environmental · L1 · Air Pollution & Clean Air

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Note~127 words · 1 min

Why Does the Ground Shake? Earth's rocky outer layer is broken into giant pieces called tectonic plates. They move very slowly — but at their edges, they can push, pull, or grind against each other. Pressure slowly builds up where two plate

Environmental

Environmental · L1 · Earthquakes: Earth's Shaking Ground

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Note~148 words · 1 min

Where Does Our Food Come From? Almost everything we eat starts on a farm. Farmers grow plants and raise animals so the rest of us have food to buy and cook. A Farmer's Year From Farm to Table Once a crop is harvested, it still has a journey

Environmental

Environmental · L1 · Farming & Growing Our Food

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Note~143 words · 1 min

Why Do We Protect Land? Some places are so special — because of their wildlife, plants, or scenery — that countries decide to protect them by law. These become national parks or other protected places. Visitor Rules How Land Becomes a Prote

Environmental

Environmental · L1 · National Parks & Protected Places

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