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Updated: Jun 8, 2026
09:55
Surface Renewal: An Advanced Micrometeorological Method for Measuring and Processing Field-Scale Energy Flux Density Data
Published on: December 12, 2013
Summary
The study reveals that dew-covered plants, particularly coniferous trees, exhibit strong retroreflection (sylvanshine) due to high water droplet contact angles. This phenomenon enhances backscattered light significantly, challenging previous explanations of similar optical effects.
Area of Science:
- Plant optics
- Bioluminescence and optical phenomena
Background:
- The heiligenschein, a bright glow on dew-covered grass, is traditionally attributed to plant hairs.
- This explanation is challenged by the discovery of sylvanshine, a similar retroreflection phenomenon observed on hairless plants.
Purpose of the Study:
- To investigate the optical properties of dew-covered plants, specifically the phenomenon of sylvanshine.
- To model the relationship between water droplet contact angle and retroreflection intensity in plants.
Main Methods:
- Development of a simple physical model to simulate light scattering from dew droplets on plant surfaces.
- Analysis of the relationship between contact angle and backscatter enhancement.
Main Results:
- Retroreflection enhancement is minimal below a 90° contact angle, similar to diffuse surfaces.
- As the contact angle increases to 140°, retroreflection enhancement rises by two orders of magnitude.
- Coniferous trees, with their typically larger contact angles, exhibit brilliant sylvanshine.
Conclusions:
- Plant hair is not essential for strong retroreflection; water droplet geometry is key.
- Sylvanshine is a significant optical phenomenon in certain plant species, notably conifers.
- The contact angle of dew droplets on plant surfaces is a critical factor in determining retroreflection intensity.
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