námraza

Námraza is a Czech and Slovak word that translates to frost or rime ice in English. It refers to a deposit of ice formed on exposed surfaces, typically occurring when atmospheric moisture (water vapor or supercooled droplets) freezes on contact with a surface that is below the freezing point of water.

The formation of námraza is dependent on several atmospheric conditions, including low temperatures, high humidity, and sufficient wind. When humid air comes into contact with a very cold surface, water vapor can deposit directly as ice through a process called desublimation, forming a feathery or granular ice deposit. Alternatively, if supercooled water droplets (water that remains liquid below 0°C) are present in fog or clouds and collide with a sub-freezing surface, they can freeze rapidly, creating a more solid, often translucent layer of ice.

Námraza can occur on a variety of surfaces, including trees, power lines, buildings, and vehicles. While visually striking, it can also have practical consequences. Significant námraza accumulation can add considerable weight to structures, leading to damage to branches, power outages, and other infrastructure problems. The appearance and texture of námraza can vary depending on the specific meteorological conditions, with different types described, such as soft rime and hard rime, based on their density and formation process.