Transient Ice Sculptures on Trees: Nature's Ephemeral Art

In winter, nature presents us with unique scenes, and one of the most mesmerizing is the ice formations on trees. Interestingly, thanks to the curved shape of the branches, rough bark, and the abundance of leaves, these icy formations emerge fleetingly and unstably. A sunbeam, reflecting off the branches, immediately warms the surface, while the wind actively promotes even heat distribution – and soon, droplets turn into ice that doesn’t remain on the branches for long.

In contrast to smooth, minimally heated surfaces such as roofs, where water can run off into massive icicles, trees behave differently. Here, constant exposure to sunlight and dynamic temperature changes prevent the ice from ever accumulating stably. Thousands of tiny icy droplets, formed under the sun, almost immediately melt under the influence of the wind and constant temperature fluctuations, turning into a spectacular but short-lived winter magic.

With the arrival of spring and the establishment of a stable light regime, the icy formations instantly give way to renewal, and the dynamic physical processes turn every moment of a winter day into a picturesque and unpredictable spectacle. This fleeting nature and variability are a reminder of how powerfully nature uses the warmth of the sun and the force of the wind to create and immediately transform its magical images.

Why do icicles not form on trees, unlike on other surfaces, and what physical processes are behind this?

Trees differ from other surfaces in terms of structure and heat exchange, so any forming icy coatings turn out to be fleeting and unstable. On smooth surfaces that naturally heat up less or “accumulate” heat (for example, a roof), water flowing off snow accumulations can freeze into large and stable icicles. On trees, however, the complex bark surface, the curved shape of the branches, and the presence of leaves create conditions for a more even distribution of solar heat, enhanced by the wind, which contributes to the rapid melting of unstable ice formations.

For example, one account describes a case in which a random sunbeam illuminated a tree in a park, and droplets of water appeared on it, eventually turning into icy icicles. However, as noted, these formations quickly disappear under the influence of temperature changes:
"A sunbeam randomly illuminated a tree in the park. Droplets of water appeared on it, which then transformed into icy icicles." (source: link )

In another excerpt, it is explained that although icy formations may appear on the branches, they do not last long due to dynamic temperature changes and the action of the wind, which is capable of dislodging even the formed fragments of ice:
"Children are amazed at the rapid changes in the products of the trees' winter fructification. Icy icicles hang on the branches, but they are not permanent. Temperature changes together with physical processes create different phenomena. Ice fragments rarely remain on sturdy branches." (source: link )

It is also noted that with the establishment of a stable light regime and the coming of spring, the ice accumulated on trees begins to melt, indicating that constant exposure to solar radiation and wind activity prevents the stable formation of icicles:
"Due to the established light regime, the leaves can remain green. ... Icicles continue to be present on the trees, but they begin to melt in the spring. Temperature changes increase the strength of the wind." (source: link )

Thus, icicles do not form stably on trees because their uneven surface, active heat exchange through solar warming, and intensified wind action cause any icy formations to either appear briefly or quickly melt. The physical processes involved include the effective distribution of heat from the sun's rays, convective cooling of the air around the branches, and wind activity that prevents the accumulation and stable formation of ice.

Supporting citation(s):
"A sunbeam randomly illuminated a tree in the park. Droplets of water appeared on it, which then transformed into icy icicles." (source: link )
"Children are amazed at the rapid changes in the products of the trees' winter fructification. Icy icicles hang on the branches, but they are not permanent. Temperature changes together with physical processes create different phenomena. Ice fragments rarely remain on sturdy branches." (source: link )
"Due to the established light regime, the leaves can remain green. ... Icicles continue to be present on the trees, but they begin to melt in the spring. Temperature changes increase the strength of the wind." (source: link )