BikeScout Encyclopedia | Shadow Persistence & Solar Angle Analysis
Description: How Shadow Persistence affects trail conditions. Learn how BikeScout calculates solar angles to identify north-facing moisture traps.
Keywords: Shadow Persistence, Solar Angle, Thermal Icebox, MTB Scouting, Solar Azimuth, hifly81, BikeScout

# Shadow
Persistence

Solar Angle & Terrain Shading Analysis

Shadow Persistence is the geospatial metric used by BikeScout to quantify how long a specific trail segment remains shielded from direct solar radiation. In the Northern Hemisphere, this primarily affects north-facing slopes (the "Dark Side"), which can stay dangerously wet while south-facing trails are bone-dry.

## The Physics: Solar Azimuth & Elevation

BikeScout calculates the Sun’s position in the sky (Azimuth and Elevation) based on the rider’s exact coordinates and the current UTC time. By cross-referencing this with the trail's Aspect (the direction the slope faces), we identify "Thermal Iceboxes".

## The "Critical 20" Rule

Through our research, we have identified the "Critical 20" threshold. When the solar elevation angle is below 20 degrees, the energy delivered to the forest floor is insufficient to penetrate the canopy and trigger evaporation. During winter or in deep valley floors, Shadow Persistence can reach 100%, meaning the mud never dries.

## Integrated Intelligence

Shadow Persistence is a key input for the TAEL Model. If a trail has high persistence, BikeScout will automatically trigger a "Traction Alert", warning the rider of potential ice or deep mud in shaded sectors, even if the regional weather forecast is "Sunny".

"The trail doesn't care about the air temperature. It only cares about the photons it receives."

#Solar-Intelligence #Aspect-Analysis #Photonic-Traction