Solar radiation across landscapes Prototype

· clear sky only (no clouds yet). Choose the physics below.

Layer

Physics

Terrain albedo

Ranges measured at six sites (docs/validation/tier3.md): snow-free ground 0.11–0.24; the snow plots 0.66–0.77. Snowy terrain with forest or rock reflected as if its albedo were 0.34–0.42, so a snow plot's albedo overstates the terrain's.

Equations used

Energy per square metre of… the sloping ground surface map area (horizontal footprint)

A slope has more surface than its map footprint. "Sloping surface" is what snow lying on the slope receives; "map area" divides by cos(slope), which is what you sum over a watershed on a map.

When

Day of the water year

Time of day

Keys on a focused slider: ← → step, PgUp/PgDn jump. While you drag, shadows come from the stored 32-direction skyline; the exact shadow march redraws when you let go.

Elevation model

Surrounding terrain: cast shadows and sky view factor

On: the skyline around each pixel (32 directions, out to 50 km) casts shadows and hides part of the sky (V_d), and in Tier 3 sets how much terrain reflects onto it. Off: each pixel is a tilted plane in flat, open surroundings (no cast shadows, V_d = (1 + cos β)/2). Slope and aspect come from the DEM either way. From zoom 6; the point panel always uses the terrain.

3D terrain Satellite imagery (Esri World Imagery) Layer opacity

Click anywhere for the point panel. The sun icon marks where the sun is overhead; the yellow line is its track over ±12 h. Dark shading = night.