Domain: Natural Science — Atmospheric Science
Target concept: Warm breath forms and gradually enlarges condensation droplets on a cold mirror.

Video generation prompt: A person holds a mirror that has been cooled in a refrigerator and exhales warm air onto the mirror's surface for several seconds.

Evaluation guide:
(i) Target concept: Condensation of water vapor via rapid cooling below dew point on a thermally conductive cold surface.
Minimum mechanism: Mirror must be significantly colder than exhaled air; exhaled air must contain sufficient water vapor; surface must be non-porous and clean to support discrete droplet nucleation (not filmwise condensation).
(ii)Storyline: [Phase 1: Pre-condition] Mirror is visibly chilled (frost, dew, or contextual cue) and held still. [Phase 2: Initiation] Mouth aligns and exhales; warm moist plume emerges and travels toward mirror. [Phase 3: Contact & Nucleation] Plume contacts surface; first discrete droplets appear at impact locus within ~1–2 seconds of contact. [Phase 4: Growth] Droplets enlarge contiguously while retaining spherical-cap shape; no evaporation or runoff. [Perspective constraint] Fixed frontal or slight oblique view showing hand, mouth, mirror, and breath path in same plane; no occlusion of droplet region; mirror surface fully visible and unobstructed throughout.

Manual:
Experimental Procedure
1. Remove a clean, dry mirror from a refrigerator (pre-chilled).
2. Hold it steadily in front of the mouth with the reflective surface facing the mouth.
3. Exhale steadily onto the center of the mirror surface for several seconds.
Observation of Experimental Phenomena
A patch of translucent, discrete, spherical-cap-shaped droplets forms at the exhalation impact zone, gradually enlarging and coalescing slightly—never forming a uniform fog or film.
Summary of Experimental Principles
Warm, moisture-saturated breath contacts a cold mirror surface; water vapor condenses into liquid droplets due to rapid cooling below dew point—demonstrating phase change driven by temperature gradient and saturation.

Prompt Grounding rubric:
level_1: No mirror appears; no human hand is visible holding anything; no exhalation or breath plume is shown; nothing suggests a cold surface; the scene bears no resemblance to a breath-on-mirror demonstration.
level_2: A mirror is present and held by a hand, but there is no exhalation shown (no breath plume, mouth not oriented toward the mirror, or mouth stays far from the glass); or the mirror shows no sign of being cold (its surface looks like an ordinary room-temperature mirror with no chill cues).
level_3: A hand holds a mirror; the mouth is positioned facing the mirror's surface; a warm breath plume is visible near the mouth and moving toward the glass; the mirror surface starts out clear and dry, with no droplets or fog present before the exhalation begins.
level_4: All elements of score 3 are present AND the mirror shows some visible cue that it was pre-chilled: for example, faint condensation on the mirror's frame or edge, or scene context (e.g., the mirror being taken directly from a refrigerator), without any pre-existing frost or dew across the reflective face itself; the exhalation continues long enough that the first droplets appear on camera.
level_5: All elements of score 4 are present AND the mirror is held steadily in a fixed orientation throughout; the mouth stays continuously aimed at the center of the mirror during the exhalation; no other object blocks the view; there is no cut, jump, or repositioning: the entire sequence, from the pre-chilled mirror to the breath onset to the first droplets forming, plays out in one continuous, unbroken shot.

Scientific and Causal Correctness rubric:
level_1: No state change observed on mirror; no droplets or fog appear; breath plume (if present) does not contact mirror; mirror remains optically uniform (no transparency change); no causal link between breath and surface effect.
level_2: Breath plume contacts mirror but no visible surface change occurs; OR surface changes but without breath contact (e.g., droplets appear before breath starts, or independently); OR change is inconsistent with condensation (e.g., uniform opaque fog without discrete droplets, or color shift like blue tint or yellow stain).
level_3: Breath plume contacts mirror surface; localized transparency reduction appears at point of contact; discrete, non-uniform, translucent droplets emerge sequentially (not instant fog); droplets increase in size over time; no evaporation or drying during video.
level_4: All elements of score 3 are present AND droplets form only where breath contacts mirror (no peripheral or off-target condensation); droplet growth is gradual and contiguous (no sudden jumps in size or coverage); no mixing with unrelated liquids (e.g., no wiping, dripping, or smearing).
level_5: All elements of score 4 are present AND droplets maintain spherical cap morphology (curved upper surface, distinct edges); no coalescence into film or runoff; no distortion of underlying mirror reflectivity outside droplet zones; droplet density increases progressively from center outward along breath path; no reversal, disappearance, or unnatural stabilization.

Spatiotemporal Consistency rubric:
level_1: Mirror or hand teleports between frames; the breath plume disappears and reappears without smoothly dispersing; the mirror's reflected highlight jumps to a different position or vanishes as though lit from a completely different angle; hand vanishes or reappears; droplets that were visible vanish instantly without shrinking.
level_2: Noticeable jitter causes the mirror or hand to momentarily blur or double; the specular highlight on the mirror flickers on and off; the breath plume starts or stops abruptly with no fade-in or fade-out; droplets pop into view fully formed rather than growing; hand grip or mirror angle changes suddenly with no in-between motion.
level_3: Hand holds the mirror steadily; breath plume travels continuously from mouth to mirror without stutter; droplets emerge and enlarge gradually rather than blinking on/off or jumping in position; the highlight/reflection visible on the mirror's surface keeps a consistent position and brightness; no tearing or warping of the mirror edge or hand.
level_4: All elements of score 3 are present AND the mirror keeps a fixed spatial relationship to the hand (no drifting, tilting, or resizing); the breath plume keeps a coherent, continuously-tapering shape as it travels; new droplets appear promptly at the spot where the plume touches the glass rather than at a delayed or mismatched location; the mirror, hand, and breath plume stay in consistent depth order with no obvious mismatch in apparent overlap.
level_5: All elements of score 4 are present AND all motion is smooth throughout: any hand adjustment is gradual and physically plausible, the breath plume shows natural dispersion as it nears the glass, and droplet growth looks continuous frame-to-frame with no sudden changes in size, shape, or position; no freezing, looping, or unnatural speed changes for any element across the full clip.