Our planet houses several unique landscapes, some of which change colour with every season. A recent post shared by the National Aeronautics and Space Administration’s Earth Observatory has highlighted the puzzling colour-changing nature of the Central Siberian plateau.
The American agency shared three vertical images of the same region changing its colour in the three seasons of summer, fall, and winter, last week. In its caption, NASA’s earth observatory mentioned that the three images were acquired by the Operational Land Imager (OLI) on Landsat 8. The images captured the breathtaking stripe patterns, twisting and turning around the hills of the northern Central Siberian Plateau around the year. It explained that on steeper hills, the stripes form tight loops that spiral from the top of the hill to the bottom.As they descend toward the banks of river Markha, they start to fade eventually disappearing at lower elevations and at latitudes.
The caption explained that there are various possible causes for the striking stripe pattern, and the answers vary by the season and by the expertise of the researcher. NASA explained that the images captured that portion of the Central Siberian Plateau that lies within the Arctic Circle, where air temperatures remain below freezing for most of the year. Most of the landscape is covered in permafrost that can be as vast as tens to hundreds of meters below the ground surface. Although the intensity of permafrost can vary, NASA explains that this specific Russian region generally has permafrost coverage for ninety percent of the year.
However, the land does thaw occasionally and this cycle of freezing and thawing is known to create myriad geometric patterns like polygon, circle, and stripe patterns on the surface. NASA explains that scientists speculate the stripes could be elongated circles stretched out on the slopes by regular thawing cycles.
According to geomorphologists, the nature of the soil is also considered as an explanation for the presence of stripes. Earth Observatory explains that soils in such cold regions can turn into Gelisols, i.e. soils with permafrost in their top two meters and often with darker and lighter layers with the unique trait of having more organic matter or more mineral and sediment content. When the ground freezes and thaws, the layers break up and blend vertically in a process called cryoturbation. With the continuous cycle of thawing and freezing through the seasons, it can cause layers to align in a striping pattern.