12/30/2023 0 Comments Ice sheet afloatIn the presence of strong winds, however, a typical structure called pancake ice forms in the wake of the rolling waves. Under calm wind conditions, a contiguous cover of thin ice forms from this still relatively transparent ice sludge. At this point, the new ice resembles a fine slurry of needles and discs. They increase in number as more heat is removed from the water. The first sea-ice crystals look like small, delicate needles or discs. For comparison, in the Baltic Sea, where the salinity is lower, the water begins to freeze at minus 0.5 degrees Celsius. In the Arctic and Antarctic, seawater has to be cooled to minus 1.9 degrees Celsius before the first ice crystals begin to form. Because seawater contains salt, its freezing point lies below zero degrees Celsius. First, frigid winds cool down the areas of open water so intensely within a short time that the surface freezes over. Sea-ice production follows the same routine everywhere. Especially in winter, when the air temperature sinks far below zero degrees Celsius and offshore winds blow constantly, sea ice is produced in the Arctic and Antarctic polynyas in assembly-line fashion. Scientists sometimes refer to them as ice factories. These areas are called coastal polynyas, and they are the places where sea ice is created. Sea-ice nurseries When strong winds in the Arctic and Antarctic regions force icebergs and sea ice away from the coasts and out to sea, areas of open water remain where air and water are in direct contact with each other.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |