In the case of leaves and other objects perched on a shallow pond or pond, the silhouette of a shadow cast on the ground is in many cases very different from the original image. In addition, a glowing frame decorates strangely distorted shadows, as if someone might trace the outlines with a bright pencil.
This can be seen, for example, with water lily leaves on relatively clear water. The shadows do not seem to care at all about the shape of the leaf in question and seem to make free use of the repertoire of potential outlines. What appears smooth and round above the water is feathered underneath – as if an image of a completely different leaf can be seen here. At first glance, this is as beautiful as it is baffling.
If you want to distinguish well all forms of water, consider clear waters of shallow depth in the sun
(Leonardo da Vinci, 1452-1519)
This amazing change is the result of a delicate interaction between the edge of the paper and the surface of the water. Water lily leaves have an air-filled fabric that makes them float. It is usually flat in the pool and slightly wavy outward. That is why it goes down alternately and rises with the rim. The tissue has a hydrophilic underside and a relatively repellent upper side, so that the water surface remains fixed to the edge of the paper and is held slightly alternately (convex meniscus) and raised (concave meniscus).
© H. Joachim Schlichting (details)
Refraction In the simplified representation, the leaf bends the surface of the water (shown in red). The incident light is refracted into a bright streak around a darker area.
These curves affect the path of sunlight in the water. But how exactly do the rays appear under the hood in some places? Maybe from where it swells? But the concave meniscus diffuses light and diffuses it over a larger area. If the gaps are created in this way, then the brightness in them should be much less. However, we don’t see this effect, especially since the edge of the shadow is limited by an intense focal line. In addition, the geometric shadow area must be smaller than the sheet due to these limitations. Indeed, the feathered image is more comprehensive – the actual shade is enlarged by the round bulges.
Laden …© H. Joachim Schlichting (details)
Shadow pillow lily | Small ripples at the edge of a sheet of paper on the water’s surface greatly change the shape of the shadow underneath.
Crucial to this is the scratches in the water due to the low areas of the edge of the paper. These are surrounded by a convex meniscus. Such a curvature refracts the light outward, enlarges the shadow accordingly, and creates a focal line at the edge.
Laden …© cisilya / Getty Images / iStock (details)
Shadow Strider Water | When a water skater presses the surface with its thin legs, it creates large round shadows.
This phenomenon is not limited to water lilies. Fallen leaves in a pond produce the same optical phenomenon. However, the effect is especially impressive, when water meters deeply raise the surface of the pool. The actual body silhouette, especially the slender legs, is almost tiny compared to the watercolor scratch-off oval shades (see photo on the left).
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