Explore sunlight on a tilted globe and a separate local horizon instrument. The selected latitude controls noon elevation, day length and daily mean top-of-atmosphere sunlight. Watch the Sun’s direction change through a circular year while the rotation axis keeps its direction.
• A real-time 3D scene with 5 inspectable parts (Tilted Earth and latitude rings, Rotation axis, Parallel sunlight direction, Selected latitude marker, Local horizon and noon ray), with home view, focus-selected-part, auto-rotate, expand, instrument-cover and hide-labels scene tools, plus a model response curve beneath the scene. • Experiment controls: Starting day after March equinox (0-364 days); Axial tilt (0-45 °); Observer latitude (-90-90 °); Days per animation second (0-12 days/s); pause/resume, 0.1 s and 1 s single-step buttons, four playback speeds and a restart button. • Live readouts: Day after March equinox; Solar declination; Noon solar elevation; Daylight duration; Daily mean sunlight; Noon horizontal sunlight. • A Geometry & measurements tab with a parameter-comparison chart, a live-measurements chart, the model equations and snapshot readouts. • An Experiments tab with 3 guided presets (June solstice north; No tilt; Polar night) and a Model verification bench that runs independent fresh models, plus a timestamped event log and a copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz with reset and a written model-scope statement linking to a technical reference.
λ=2π day/365.2422; δ=asin(sin ε sin λ) cos H0=−tan φ tan δ, with explicit polar-day/night limits Daylight=24 H0/π; noon elevation=asin(sinφ sinδ+cosφ cosδ) Daily mean Q=1361/π [H0 sinφ sinδ+cosφ cosδ sinH0] W/m²
Circular year referenced to March equinox, no calendar leap-year conversion. No atmospheric refraction, scattering, cloud, terrain or climate response. Quantities are incident sunlight, not surface temperature. Sun and globe sizes are illustrative; physical rotation is omitted to emphasize seasonal geometry.
No. Tilt changes solar elevation and the duration of daylight.
No. Atmosphere, thermal storage and climate processes are not solved here.
Circular year referenced to March equinox, no calendar leap-year conversion. No atmospheric refraction, scattering, cloud, terrain or climate response. Quantities are incident sunlight, not surface temperature. Sun and globe sizes are illustrative; physical rotation is omitted to emphasize seasonal geometry.