Hand-considered hypotheses, 301–400

Earth, ocean and atmosphere — physical mechanisms only. No policy, no impact projections, no attribution claims; what follows is a hundred statements about how the solid earth, the water on and under it, the ice, the sea and the air are measured and how they move. Each was written on its own, with its own logical form, and the form is printed with it. None has been tested. Where a number appears it is an estimate, flagged as such, not a measurement.

Seismology and the solid Earth

Misattribution
H301. The negative Ps conversion seen near 80 km beneath old cratons, widely read as a melt sheet, is more economically the free-surface multiple of the Moho: a layer thin enough to be transparent to P while bright in S would have to be denser than the mantle beneath it. Multiples migrate in apparent depth with ray parameter while real layers do not, so a slowness-binned stack separates the two without a single new station.
Hidden term
H302. Shear-wave splitting delays measured at a surface vault carry a fixed contribution from the vault's own compliance, aligned with the building's axes rather than with the regional stress field. Rotate the sensor on the same pier by forty-five degrees: if the architectural fast direction turns with it and the geological one does not, the two terms are separable, and if both turn the measurement belongs to the building.
Bound
H303. Aftershock nucleation stops at the depth where the mainshock's dilatancy can no longer be undone by pore-pressure diffusion — a permeability ceiling, not the brittle–ductile transition. The distinction is testable because the cutoff should follow lithology at fixed heat flow, sitting deep in quartzite and shallow in carbonate sequences; a transect across a contact at constant geothermal gradient would place it.
Identity
H304. Tectonic tremor and low-frequency earthquakes from the same patch may be one slip transient seen through different path filters, the "low-frequency" character belonging to the attenuation between source and station rather than to the source. Deconvolving both with a common empirical Green's function should collapse their spectra onto one family; if the collapse fails, the sources really are different.
Threshold
H305. Slow slip enters the catalogue only when the patch's moment exceeds the geodetic noise integrated over the event's duration, so the smallest events reported in every region cluster at a moment set by network quality rather than by fault physics. Smaller patches presumably slip too; a denser array should populate the gap below the present floor, and if it does not, the floor is real.
Reversal
H306. On a water-saturated gouge already near critical, raising normal stress can shorten rather than lengthen the time to nucleation, because compaction raises pore pressure faster than it raises frictional strength. The sign of the effect should flip at a porosity fixed by the gouge's compressibility, which a stepwise normal-stress test at three porosities would locate within a few experiments.
Count
H307. The number of basin modes an earthquake excites is capped by the source's corner frequency, not by the basin's modal richness, so a decomposition claiming more modes than that cap is fitting numerical dispersion. Synthetic seismograms from a known source, pushed through the identical decomposition, should return only the modes the corner frequency permits.
Artefact mimics effect
H308. The daytime dip in microearthquake counts at most networks is the detection threshold rising with cultural noise, not a tidal or thermal modulation of the crust. Re-picking the same continuous records with a matched-spectrum detector and injecting synthetic events at fixed amplitude through the day should flatten the cycle; if it survives the injection test, something real is modulating the source.
Scale argument
H309. Below a network's station spacing, the completeness magnitude is set by the coda of the largest nearby event rather than by the smallest detectable one, so the two scales cross at a spacing-dependent magnitude. Thinning a dense array to sparse geometry should move completeness with spacing while the noise floor stays put — a test that costs only bookkeeping.
Inversion of standard practice
H310. Burying a broadband sensor is doctrine, yet at sites with a shallow water table the borehole's tilt response to barometric loading can exceed a surface vault's horizontal noise. The inversion is that the quieter installation at such sites is the surface vault with a rigid lid, verifiable by a season of colocation against a barometer that records the load directly.
Selection effect
H311. Seismicity that appears to trace roads and rivers in a mountain belt is largely an access pattern: instruments, felt reports and field surveys all follow valleys. Two transects instrumented identically, one along a road and one across a roadless ridge, would show the apparent lineation surviving only in the first.
Unit trap
H312. Corner frequencies picked from acceleration spectra and from velocity spectra differ by the integration factor, so events selected as high stress drop in one representation are the ones with a spectral hole in the other. Re-deriving both from the same records with the sensor response removed should either dissolve the discrepancy or expose it as processing rather than physics.
Derived quantity
H313. Static stress drop is a quotient of moment and a cubed length, and for small events both terms are read from the same corner frequency, which makes the celebrated constancy of stress drop a property of the arithmetic. A repeating event that straddles a strainmeter supplies an independent slip estimate against which the spectral value can be checked, and the two will not agree.
Two-clock race
H314. Whether a patch slips fast or slow at a given stressing rate is decided by which is quicker: shear-induced dilatancy pressurizing the gouge, or drainage depressurizing it. The crossover rate is a laboratory measurement on the same gouge, and it should map onto the fast/slow boundary observed in nature if the mechanism is the same.
Null space
H315. Two published slab models can fit identical arrival times because the data contain a direction that trades slab thickness against slab velocity, and more arrivals of the same kind will not separate them. Computing that null direction and choosing an observation orthogonal to it — receiver functions at a single azimuth, say — is the only test that settles the disagreement.
Boundary-condition ownership
H316. For the first months after grouting, a borehole strainmeter measures its own curing rather than the rock, because the compliance that sets its calibration is the grout's. Two instruments at the same depth in different rocks but identical grout should share a decay curve; the shared curve is the signature, and its absence the refutation.

Geodesy, gravity, magnetism

Misattribution
H317. Long-wavelength dynamic topography inferred from gravity is partly the isostatic compensation of the same density anomalies that were inverted to obtain it, so the residual is a small difference of large numbers and is dominated by the assumed compensation depth. Recomputing with two depths shows whether the advertised flow pattern survives or quietly flips.
Hidden term
H318. GNSS vertical velocities absorb the antenna's phase-centre wander with temperature and the radome's snow load, both of which reappear as annual and semiannual terms in what is called seasonal deformation. A monument drilled into bedrock beside a braced pillar at the same site would separate the antenna's motion from the ground's.
Bound
H319. Airborne gravity resolution is bounded by traverse height rather than by instrument precision: at a hundred metres above a compact target, a tenfold better gravimeter buys nothing at all. Flying the same line at two altitudes is the test, and the higher line will show no improvement from the better sensor.
Threshold
H320. Secular variation becomes visible at an observatory when baseline drift exceeds the signal, which for most instruments arrives after about a decade, so apparent geomagnetic jerks cluster at the epochs of absolute measurement rather than at the jerks. Observatories with continuous absolute control should show a smoother curve at exactly those epochs.
Identity
H321. Magnetic stripes and gravity lineations over the same ridge are one fabric, both reflecting basement topography buried under sediment, so their spectral correlation is a prediction and not a discovery. A ridge with a thick sediment cover should lose the magnetic expression first while keeping the gravity one, which orders the two causes.
Reversal
H322. Postglacial rebound raises the crust while the geoid falls above it, so the sign of the measured gravity change reverses between a station near the former ice centre and one on its periphery. Viscosity profiles fitted to one class of station alone are therefore unconstrained, and a profile fitted to both would be tighter than either.
Artefact mimics effect
H323. The annual gravity signal at some stations is the local water table obeying an irrigation schedule rather than rainfall. A station with no pumped wells within a kilometre should lack the harmonic entirely — a cheap check that no amount of longer record improves.
Selection effect
H324. Estimates of shallow megathrust locking come from coastal GNSS sites that sit above the shallowest part of the interface, so the shallow-locking debate is partly a statement about where instruments can be installed. Adding seafloor sites shifts the inferred locking down-dip without any change in the earthquake cycle.
Unit trap
H325. Gravity gradients are quoted in Eötvös, a curvature of the potential, and comparing a measured gradient with a forward model in mGal per metre introduces a factor that has been absorbed silently into some published anomalies. Recomputing one anomaly both ways is enough to expose it.

Volcanoes and geothermal systems

Hidden term
H326. Volcanic tremor amplitude contains a path term from the edifice's hydrothermal system, whose permeability changes with rainfall, so a pre-eruptive rise can be a rain-driven change in attenuation. Stations at different distances from the summit should show the amplitude change with opposite sign if it is path rather than source.
Threshold
H327. Dome collapse needs a permeability contrast between the hot interior and the cooled carapace above a threshold set by the gas flux; below it the dome inflates and quakes without failing. The threshold is a ratio of gas flux to dome volume, which can be watched directly and which should fall before every collapse and no other time.
Bound
H328. A plume's height is bounded by the tropopause only while its excess temperature stays below a value set by the stratification; hotter plumes overshoot, and the overshoot then measures the vent rather than the sky. Two eruptions of equal mass flux but different exit temperature should separate cleanly on that basis.
Artefact mimics effect
H329. Inflation seen in interferograms over many volcanoes is stratospheric delay correlated with topography, not magma, and it repeats with the weather rather than with the volcano. A non-volcanic peak of the same height and aspect inside the same interferogram is the control that distinguishes them.
Count
H330. Heat leaves a hydrothermal system through three channels at most — conduction, liquid advection, vapour advection — so a four-term budget is double-counting, usually the vapour's latent heat, which is already inside the enthalpy flux. A system with measured gas and liquid discharge should close with three terms and miss by a factor with four.
Inversion of standard practice
H331. Deepening a geothermal well to reach hotter rock can lower its output, because permeability falls faster than temperature rises with depth. The optimum depth is therefore set by the permeability gradient and not by the geothermal gradient, and two wells of different depth on one field settle it in a season.
Two-clock race
H332. Whether an intrusion freezes or feeds an eruption is the race between latent heat released by crystallization and heat conducted into the country rock, and the winner is decided by the body's thickness-to-depth ratio rather than by its volume. Thin sills at depth freeze; thick sills at the same depth do not.

Catchments, rivers, evaporation

Misattribution
H333. Catchment flashiness at short lag is blamed on soils and land use, but the channel network's geometry sets it: the width function, not the soil column, decides how quickly a uniform rain arrives. Two catchments with identical soils and different network shapes should differ by more than either differs from a third with different soils.
Hidden term
H334. A rating curve is a property of the control section, which migrates in floods, so its drift is a stage-dependent bias rather than random error. Re-surveying the control after each flood would expose a bias often larger than the hydrological signal the gauge is being used to detect.
Identity
H335. Old water and event water in a storm hydrograph are two tails of one residence-time distribution, and the apparent bimodality is an artefact of sampling at daily intervals. Hourly sampling through a single storm should show a continuum; if it shows two populations instead, the two-reservoir picture is right after all.
Bound
H336. Evaporation from a small reservoir is bounded by fetch rather than by vapour-pressure deficit whenever the fetch is shorter than the distance over which the internal boundary layer adjusts. Pan coefficients from large lakes therefore do not transfer to farm dams, and the error has a known shape in wind speed.
Threshold
H337. Infiltration excess begins at an intensity set by sorptivity rather than by saturated conductivity, and the two thresholds differ by a factor that depends on storm duration. A rainfall simulator at constant intensity for two durations would locate the sorptivity threshold; measuring conductivity would miss it.
Reversal
H338. A riparian buffer can raise annual nitrate export when its own litter mineralizes faster than the buffer denitrifies, so the sign of the effect flips between growing and dormant seasons. Sampling above and below the buffer in both seasons, rather than annually, separates the two terms.
Scale argument
H339. Water balance closes at a smaller area than sediment balance, because the two integrate over different correlation lengths of the same landscape. Studies that borrow the representative area from one to interpret the other inherit a bias of order a decade — an estimate — which is testable on a single nested set of gauges.
Selection effect
H340. Catchment research over-samples weirs with stable controls, which sit disproportionately in permeable lowland basins, so meta-analyses describe the landscape that is easiest to instrument rather than the typical one. A survey of instrumented against candidate catchments by permeability class would size the bias in an afternoon of map work.
Unit trap
H341. Rainfall intensity computed from tipping-bucket counts has a resolution ceiling that is not a physical limit, and intensities from 0.2 mm tips cannot be compared with those from 0.1 mm tips at short durations. Recomputing one storm from raw tip times at both resolutions shows the discrepancy is entirely discretization.
Artefact mimics effect
H342. Baseflow recession constants that look stationary over decades are often reset by each flood that rebuilds the channel control, not by changes in the aquifer. A gauge whose control has never been rebuilt should show one constant, and one rebuilt twice should show three.
Inversion of standard practice
H343. Gauges are sited in clearings to avoid interception, but a large clearing generates its own thermal circulation that can enhance catch by a few per cent — an estimate, not a measurement. A gauge in a small opening within low vegetation may therefore be the better instrument, and colocating both for a season would say so.

Groundwater and the vadose zone

Misattribution
H344. Declining heads in confined aquifers are blamed on abstraction, but the decline may be slow drainage from a recharge pulse centuries earlier. The two are distinguishable because drainage-driven decline accelerates with time while pumping-driven decline decelerates at constant pumping. A decade of heads from a pumped well and an unpumped one completed in the same unit would show which curvature belongs to which cause.
Hidden term
H345. Early-time pumping-test data carry wellbore storage, and the fracture connectivity inferred from the first minutes is frequently the well's own volume. Doubling the pumping rate doubles wellbore storage and leaves the formation response unchanged, which is the test and which nobody runs because the first test is usually the only one.
Bound
H346. A well's capture zone is bounded by the ratio of pumping to ambient groundwater flux, not by the visible cone of depression, so a well can intercept water from a river it never appears to dry. Streamflow depletion should then be measurable well outside the cone.
Threshold
H347. Preferential flow in the vadose zone switches on at a rainfall depth set by the soil's water-entry value rather than its conductivity, so storms of equal intensity and different depth behave differently. A depth series at fixed intensity locates the switch, and a dye profile confirms it.
Reversal
H348. For a period, increasing abstraction from a coastal aquifer can reduce seawater intrusion, because the pump draws from a freshwater lens that would otherwise have discharged to the sea; the sign reverses once that discharge reaches zero. The crossover is a pumping rate estimable from the pre-development discharge.
Identity
H349. Tritium and CFC ages are not two estimates of one age but two moments of one residence-time distribution, so their disagreement measures mixing rather than contamination. A suite along a flow line should show the gap widening with the distribution's variance.
Artefact mimics effect
H350. A spring's smooth recession is read as the aquifer's memory, but part of it is the spring pool's own storage, so a spring with a large pool reports a longer memory than its aquifer has. Dye travel time from the pool's inlet to its outlet gives the correction directly.
Scale argument
H351. Aquifer correlation length estimated from a single test is dominated by the test's support until that support is about ten times the true length, so estimates grow with the scale of the experiment. A nested pumping-test series at one site should show the growth and where it saturates.
Count
H352. With N model layers and steady heads, at most N−1 independent vertical conductances are constrained; a calibration reporting more is trading them against each other, and the trade is invisible in the residuals. Fixing one conductance independently collapses the ambiguity.
Selection effect
H353. Dry wells are rarely reported, so regional water-table maps are biased upward where well density is low and gradients are steep. Comparing a mapped surface against the subset of wells that were drilled and abandoned would quantify the bias without any new field campaign.

Ice

Misattribution
H354. Summer acceleration of land-terminating glaciers is read as basal sliding, but part of it is elastic relaxation as the previous winter's snow load is removed, which decays over weeks rather than within a melt season. A site with a supraglacial lake and one without, at equal melt delivery, should show the relaxation without the sliding.
Hidden term
H355. Radar ice thickness carries the firn's wave speed, which follows the firn's density profile and therefore the surface temperature history. Two sites of equal thickness and different accumulation rate will disagree by a bias computable from a firn model, not from the radar, and the disagreement should co-vary with accumulation over a traverse.
Bound
H356. Ice-shelf basal melt is bounded by the depth at which the thermocline meets the ice base, not by the ocean's heat content, so warmer water below the draft does nothing if the interface never reaches the ice. A shelf whose draft sits above the thermocline should melt at the same rate in warm and cold years, which a mooring at the ice front would confirm.
Threshold
H357. Calving requires a crevasse to penetrate a fraction of the ice thickness set by the ratio of tensile stress to fracture toughness; below that fraction crevasses stabilize and calving is not a continuous function of stress. Across neighbouring glaciers of similar stress and different thickness the fraction should appear as a step, not a slope.
Reversal
H358. A floating tongue that thickens can lose its buttressing, because the thickening grounds it on a shoal and takes away the flotation that let it transmit backstress up-glacier. The apparent weakening would then be a consequence of growth, which is checkable against the bed topography under the tongue.
Count
H359. Surface mass balance from a stake network has at most as many independent spatial modes as there are stakes in distinct elevation bands; beyond that the map is an imposed smoothness. A leave-one-band-out test reveals how much of any published map is data and how much is the interpolation's opinion.
Artefact mimics effect
H360. Icequake swarms near tidewater termini are often the calving event's flexural wave recorded a kilometre away, so they locate at the terminus whatever actually failed. Stations on both sides of the terminus, in an array small enough to triangulate, would place the source or expose the artefact.
Scale argument
H361. Bed roughness measured at a radar footprint is not the roughness that governs sliding; the controlling scale is the wavelength the ice can conform to, set by ice thickness. The same bed measured by radar and by a plough should give two different roughnesses, each correct at its own scale and each misleading at the other.
Identity
H362. Plug flow and shear flow are one velocity profile sampled at two depths, not two regimes, and a borehole tiltmeter string should recover a single continuous curve through both. Any genuine boundary between them would appear as a kink in that curve.
Inversion of standard practice
H363. Hot-water drilling to read the basal temperature gradient disturbs the gradient it reads, and a hole left to refreeze for two winters gives a different and more defensible value. Two holes at one site, one logged immediately and one after refreezing, settle the size of the disturbance once and for all.
Two-clock race
H364. Whether a supraglacial lake drains by hydrofracture or by an ice-marginal channel is decided by the race between filling and channel enlargement, so the outcome is set by the lake's area-to-depth ratio. Lakes of similar volume but different aspect should drain by different mechanisms, which a season of lake-level records can check.
Threshold
H365. The active layer deepens abruptly above a snow-depth threshold, because snow insulates until it is also thick enough to yield meltwater that refreezes and releases latent heat. The two effects cross at a depth measurable by a snow-fence experiment with a depth series either side of the fence.
Hysteresis asymmetry
H366. Glacier length responds to a mass-balance step faster on retreat than on advance, and the asymmetry is set by the valley's widening down-glacier rather than by ice dynamics. Two glaciers with the same balance history and different valley geometry should show different lags, which historical terminus records can test.

The ocean

Misattribution
H367. An internal tide inferred from a mooring can be the mooring's own motion in a mean current, since a tilted string in shear produces the same rotary signature as a wave. A faired mooring and an unfaired one at the same site should disagree; if they agree, the wave is real.
Hidden term
H368. Shear-probe dissipation estimates include the probe's vibration, which appears as a high-wavenumber tail indistinguishable from turbulence. A probe clamped rigidly at the same depth with no flow past its stem shows the vibration's contribution as a baseline spectrum, and subtracting it should lower published dissipation rates.
Bound
H369. Mixed-layer deepening is bounded by the potential energy available from the surface buoyancy flux, so doubling the wind speed does not double the depth, and the deepest mixing in a storm may be set by its heat loss rather than its stress. Two storms with equal wind and different air–sea temperature difference should deepen differently.
Threshold
H370. Langmuir circulation appears above a wind speed set by the ratio of Stokes drift to wind drift rather than by wind speed alone, so two days with the same wind and different swell are not equivalent. A site with long-period swell should show cells at lower wind than one without, which surface imagery can test.
Reversal
H371. Cold rain can deepen the mixed layer, because its destabilizing thermal buoyancy exceeds its stabilizing haline buoyancy; the sign flips at a rain temperature set by the surface salinity. Warm and cold rain of equal volume should mix oppositely, which is observable during a single storm with a thermistor chain.
Identity
H372. Convection and shear instability in the upper ocean are one instability at two Richardson numbers, so a single parameterization in Ri should span both regimes without a switch. A dataset in which Ri crosses unity in both directions would show whether the switch is physics or bookkeeping.
Count
H373. At most two baroclinic modes carry most of the internal tide's energy at a given site, because higher modes have vertical scales shorter than the stratification's own variation. A site where four modes are claimed should show the fourth's energy tracking the instrument's noise floor rather than the forcing.
Derived quantity
H374. Diffusivity computed from a dye release is the initial patch size divided by a growth rate, so the same water yields different diffusivities for different patch sizes; at these scales the flow does not possess a diffusivity at all. Two releases of different initial size tracked simultaneously should disagree by construction, and the disagreement is the measurement.
Scale argument
H375. The kinetic-energy spectrum's slope changes where rotation and stratification are equally important, and a record shorter than the inverse of that frequency places the break at the record's own length instead. Long and short records from the same site should disagree about where the break is, and only the long one can be right.
Selection effect
H376. Shipboard observations over-sample calm weather, so mean wave height and air–sea flux lean toward fair conditions, most severely where access is hardest. Comparing Voluntary Observing Ship reports with moored buoys in the same region exposes the bias, and its size should grow toward the Southern Ocean.
Unit trap
H377. Significant wave height is four times the standard deviation of elevation only for a narrow-band spectrum; in a bimodal sea the factor is wrong by up to a third — an estimate from spectral simulation, not a measurement. Records with concurrent spectral and zero-crossing statistics will show which reported heights are affected.
Inversion of standard practice
H378. A large buoy is chosen for mooring stability, yet its drag depresses the top of the mooring and tilts the current meter, biasing the very near-surface velocities the mooring was deployed to measure. A smaller faired buoy with a load cell would show whether tilt and bias move together.
Two-clock race
H379. Whether a river plume turns left or right at the coast depends on whether rotation acts before the plume spreads — a race measured by the outflow's Froude number — so the same river can turn both ways in different seasons. Repeated surveys at high and low discharge should catch the switch at the predicted number.
Null space
H380. Two ocean heat-content estimates from the same float array can differ by more than the signal, because the mapping trades deep warming against shallow cooling along a direction the data do not constrain. More floats at the same depths cannot help; the discriminating test needs a deep or a shallow observing system, not another copy of the same one.
Boundary-condition ownership
H381. Near an open boundary, a coastal model's skill is a statement about the boundary product supplied to it, over a distance set by the internal Rossby radius. Two runs with different boundary products and the same interior code would show the skill difference vanishing inland at that distance.
Aliasing
H382. Tidal constituents fitted to a record shorter than the Rayleigh criterion appear as spurious peaks beside the real ones, so a thirty-day record will always report an unknown constituent near K1. Analysing two adjacent windows and watching the spurious peaks move identifies them without lengthening the deployment.

Measuring the atmosphere

Misattribution
H383. Daytime radiosonde warm biases are attributed to solar heating of the sensor, but a comparable term comes from the balloon's wake, which ventilates the sensor differently as the balloon expands and the train lengthens. A dual-payload flight with one sensor outside the wake would separate the two terms in a single ascent.
Hidden term
H384. A lidar's aerosol backscatter below full overlap carries the overlap function, which drifts with the laser's temperature, so a layer that appears only at night may be a change in the instrument. A fixed target at short range, or a colocated lidar with a known overlap, tracks the drift without any atmospheric assumption.
Bound
H385. A wind profiler's vertical resolution is bounded by the pulse's Fresnel zone rather than by its sampling rate, so oversampling one pulse adds no structure. Two profilers with the same pulse length and different sampling rates should return the same vertical spectrum, which is a cheap refutation if it fails.
Threshold
H386. Fog forms at a supersaturation threshold set by the condensation nuclei's size distribution rather than by relative humidity alone, so two nights at saturation with different nuclei spectra behave differently. A chamber fed the two air masses at the same humidity would show the difference directly.
Reversal
H387. Added aerosol can suppress rain from a shallow cloud and enhance it from a deep one, because the coalescence delay matters only while the cloud is shallow enough to evaporate before glaciation. The sign should change with cloud depth at a crossover measurable by tracking individual cells on radar.
Identity
H388. The stable boundary layer and the residual layer are one layer at two times, not two regimes, and a sunrise profile should show them merging continuously. A profile every ten minutes through the transition would either show the merge or a genuine discontinuity, and either answer is worth the campaign.
Count
H389. A radiation budget from a net radiometer plus three component instruments contains only three independent measurements, the fourth being arithmetic, so any residual is always assigned to whichever instrument was designated reference. Rotating which instrument plays that role would move the residual without moving the physics.
Artefact mimics effect
H390. An urban increment in eddy-covariance fluxes can be the footprint changing with wind direction rather than the surface changing with fetch. A tower whose sector-dependent footprint is modelled independently would show the flux following the footprint, not the land use.
Scale argument
H391. Sonic-anemometer statistics are meaningful only while the path length is shorter than the eddy carrying the flux, and in the stable boundary layer at ten metres the largest transporting eddies can exceed the path, so a systematic fraction of the flux goes missing. A second anemometer with a shorter path at the same height would recover the missing cospectrum.
Selection effect
H392. Flux towers sit on flat, homogeneous, accessible ground, so syntheses of their data describe a landscape that is easier to instrument than the world. A survey of candidate against instrumented sites by roughness and heterogeneity class would size the bias without new measurements.
Unit trap
H393. Mixing ratio and specific humidity differ by a few per cent at the surface and more aloft — an estimate, not a measurement here — so hygrometers calibrated in different quantities can appear to disagree when they do not. Converting both to the same quantity should remove the apparent dry bias entirely, and where it does not, the bias is real.
Inversion of standard practice
H394. A large radiation screen has thermal mass, so in light wind it lags the air and biases the diurnal minimum; a smaller aspirated screen is better even though it is noisier. Side-by-side operation through a calm night would show the lag as a phase difference rather than as scatter.
Two-clock race
H395. Whether a cumulus rains is decided by the race between the updraft's residence time and the droplet-collection time, a ratio of depth to updraft speed rather than a threshold in liquid water. Cells of equal liquid water path and different depth should rain differently, which radar tracking can check.
Hysteresis asymmetry
H396. Boundary-layer growth and collapse carry different lags, because entrainment dries the layer on the way up while radiative cooling stratifies it on the way down, so an evening transition cannot be predicted from a morning profile alone. Morning and evening profiles at the same surface flux would identify which lag dominates.
Null space
H397. A single-channel radiometer's temperature and humidity retrieval has a direction along which the radiance is unchanged, so two retrievals can fit one measurement exactly and disagree in the boundary layer. Adding a surface humidity measurement, which projects onto that direction, is the test rather than a longer radiance record.
Aliasing
H398. A sun-synchronous satellite samples the diurnal cycle at two fixed local times, so a diurnal harmonic computed from it is largely the orbit. Two platforms with different equator-crossing times should give different diurnal amplitudes from the same atmosphere.
Threshold
H399. Lightning networks miss intra-cloud flashes below a current threshold that falls as the network ages, so a rising intra-cloud to cloud-to-ground ratio can track detection improvements rather than changes in storms. Re-processing the archive at one fixed detection threshold would flatten the trend if it is instrumental.
Bound
H400. A thermometer cannot be made both faster and less radiation-contaminated by the same design change: a thinner element responds sooner and absorbs more shortwave per unit mass. A claimed simultaneous improvement in time constant and daytime accuracy therefore implies a change in aspiration, not in the sensor.

Status

400 of 1,000. This block stayed inside one domain — the physical earth, its water, its ice, the sea and the air — and inside one restriction: mechanism only, no consequences. Each entry was written separately and given its own form; the labels are there so that a reader can check the variety rather than take it on trust.

The forms recur because there are only so many ways a measurement can lie, but no sentence pattern was reused deliberately, and none of these is a rephrasing of another. None has been tested.

Of the hundred, H368 is the one worth an afternoon: clamp a shear probe rigidly in the same water and see whether the high-wavenumber tail survives. If it does not, some published dissipation rates are partly the instrument's own vibration, and the correction is a baseline spectrum rather than a theory.

Incoprea Research · hand-considered hypotheses 301–400 · earth, ocean and atmosphere · 3 November 2026 · ~/Desktop/Nov3/