Snow Rolls

Snow rolls is a rare natural phenomenon in which a layer of snow, under the influence of wind and specific meteorological and surface conditions, rolls and forms cylindrical structures. These structures arise when snow detaches from the surface and rotates around its own axis, typically resulting in hollow centers. Their sizes can range from a few centimeters to several meters in length. Factors influencing the formation of snow rollers include the physical properties of the snow, temperature, wind speed and direction, terrain slope, and surface roughness.

Snow rollers observed in Amasya in April 2025 (Anadolu Agency)

Formation Conditions

Snow rollers form when temperatures are near freezing and the snow surface still exhibits sticky properties. During this time, the wind lifts portions of the snow layer from the ground and initiates rolling; as the snow moves, it accumulates additional layers on its outer surface, gradually adopting a cylindrical shape. The snow must be moist, sticky, and sufficiently dense; excessively dry or overly wet snow prevents roller formation. If wind speeds are too low, rolling does not begin; if they are too high, the rollers disintegrate. Ground conditions, terrain slope, and wind direction also play decisive roles in the formation process: slopes facilitate the wind’s ability to move snow downward, while rollers can still form on flat terrain under suitable wind and snow conditions. The hollow center of the rollers results from the thinness of the initial layers and their transfer to the outer surface.

Historical Observations

Mount Pleasant, Michigan (1906)

The first scientific observations of snow rollers were conducted in 1906 in the Mount Pleasant region of Michigan. These observations revealed that under nighttime winds shifting direction and temperatures around 1–2 °C, portions of the snow layer detached from the surface and rolled into cylindrical shapes. The rollers typically had diameters between 7 and 30 cm and exhibited a spiral structure. Formation was also observed on flat surfaces and gentle slopes. The processes of melting and refreezing played a key role in loosening the snow layer, making it more mobile under wind action.

Iowa (1932)

Observations in Iowa in 1932 demonstrated that snow rollers can also form on flat terrain. During the night of 25–26 January, thousands of snow rollers developed after a layer of moist snow fell atop an existing snow crust. The rollers, ranging in diameter from the size of an egg to that of a barrel, left trails up to 20–100 feet long. This event highlighted the critical role of wind direction changes and temperature drops in the formation of snow rollers.

Examples in Türkiye

Amasya

One of the areas in Türkiye where snow rollers have been observed is the Dereli Yaylası plateau, part of the Taşova district in Amasya. This natural phenomenon was recorded in the winter and early spring months of 2025. The snow rollers formed when snow detached from the surface due to wind action during periods when air temperatures were near freezing. Observations in the Dereli forests indicated that wind direction, terrain slope, and the sticky nature of the snow were decisive factors in the formation of these structures. These observations confirm that snow rollers can occur in Türkiye when suitable meteorological and topographical conditions are present.

Ilgaz Mountain

Another example was observed in January 2026 on Ilgaz Mountain, located on the border between Kastamonu and Çankırı. Snow rollers formed when the wind detached snow from the ground and rolled it down sloped terrain, under a snow layer approximately 80 centimeters thick. Snow rollers of varying sizes were seen along roadside areas, demonstrating that similar conditions can occur in high-altitude mountainous regions.

Snow rollers observed on Ilgaz Mountain in January 2026 (Anadolu Agency)