for kakato's edification.
What is the difference between sea ice and icebergs, glaciers, and lake ice?
The most basic difference is that sea ice forms from salty ocean water, whereas icebergs, glaciers, and lake ice form from fresh water or snow. Sea ice grows, forms, and melts strictly in the ocean. Glaciers are considered land ice, and icebergs are chunks of ice that break off of glaciers and fall into the ocean. Lake ice is made from fresh water and freezes as a smooth layer, unlike sea ice, which develops into various forms and shapes because of the constant turbulence of ocean water.
The process by which sea ice forms is also different from that of lake or river ice. Fresh water is unlike most substances because it becomes less dense as it nears the freezing point. This difference in density explains why ice cubes float in a glass of water. Very cold, low-density fresh water stays at the surface of lakes and rivers, forming an ice layer on the top.
In contrast to fresh water, the salt in ocean water causes the density of the water to increase as it nears the freezing point, and very cold ocean water tends to sink. As a result, sea ice forms slowly, compared to freshwater ice, because salt water sinks away from the cold surface before it cools enough to freeze. Furthermore, other factors cause the formation of sea ice to be a slow process. The freezing temperature of salt water is lower than fresh water; ocean temperatures must reach -1.8 degrees Celsius (28.8 degrees Fahrenheit) to freeze. Because oceans are so deep, it takes longer to reach the freezing point, and generally, the top 100 to 150 meters (300 to 450 feet) of water must be cooled to the freezing temperature for ice to form.
Can you drink melted sea ice?
New ice is usually very salty because it contains concentrated droplets called
brine that are trapped in pockets between the ice crystals, and so it would not make good drinking water. As ice ages, the brine eventually drains through the ice, and by the time it becomes
multiyear ice, nearly all of the brine is gone. Most multiyear ice is fresh enough that someone could drink its melted water. In fact, multiyear ice often supplies the fresh water needed for polar expeditions. See
Salinity and Brine in the Characteristics section for more information.
All About Sea Ice, Introduction :: National Snow and Ice Data Center