Nilasjää

Nilasjää, also known as new ice or young ice, is an early stage of sea ice formation that occurs in polar and subpolar regions. It develops when the surface of the ocean begins to freeze in cold conditions, typically during the winter months in the Arctic and Antarctic. Nilasjää is characterized by its thin, translucent appearance, often appearing grayish-blue or greenish in color due to the presence of air bubbles and brine pockets within the ice. The term originates from Finnish, where *nilas* means "foam" or "froth," reflecting its initial, frothy texture as it forms.

This type of ice is typically less than 10 centimeters thick and forms when the water temperature drops below the freezing point, causing a thin layer of ice to solidify on the surface. Nilasjää is highly dynamic, constantly shifting and breaking due to wind, waves, and currents. Over time, as it thickens and consolidates, it transitions into more stable forms of sea ice, such as gray ice or shuga, before eventually developing into first-year or multi-year ice.

Nilasjää plays a crucial role in the Arctic and Antarctic ecosystems, serving as a habitat for various marine organisms and influencing oceanic and atmospheric processes. It also contributes to the Earth's climate system by reflecting sunlight back into space, a phenomenon known as the albedo effect. The study of nilasjää is important for understanding sea ice dynamics, climate change impacts, and the broader interactions between the cryosphere, ocean, and atmosphere. Researchers monitor its formation and behavior using satellite imagery, field observations, and ice buoys to improve climate models and predictions.