This image of Sentinel-2 satellites was taken on April 13, 2025 and shows Lake Võrtsjärv, the second largest lake in Estonia, during the spring thaw. On the surface of the lake, you can see very distinct greenish whirlwinds. These indicate the presence of sediment suspended in water. Such patterns are typical of this period of the year, because the melting of snow and ice coming from the surrounding landscapes leads to the movement and the deposit of fine sediments in the lake. All this water joins the lake and creates fascinating surface movements, in particular in the shallow areas where the wind and the agitation of water further redistribute the material.
As in many other areas, the European space program Copernicus provides crucial data to monitor seasonal changes in water quality, but also support conservation measures. Thanks to the information collected, the authorities can improve their management of ecologically sensitive areas, by reconciling biodiversity protection and local subsistence means.
