- When water freezes, most impurities are expelled from the ice crystals, resulting in the formation of cavities containing salt-water brine, and thus making sea ice very porous.
- The surrounding water becomes more saline as concentrated brine leaks out.
- The brine-rich water remains liquid, and its increased density causes this water to sink, setting the stage for the creation of a "brinicle".
- Its outer edges begin accumulating a layer of ice as the surrounding water, cooled by this jet to below its freezing point, ices up in a tubular or finger shape and becomes self-sustaining.
- The down-flowing cold jet continues to grow longer downward, and reach the seafloor.
- It will continue to accumulate ice as surrounding water freezes. The brine will travel along the seafloor in a down-slope direction.
A brinicle (brine icicle, also known as ice stalactite and briner cold) is a downward-growing hollow tube of ice enclosing a plume of descending brine that is formed beneath developing sea ice.
As seawater freezes in the polar ocean, salt brine concentrates are expelled from the sea ice, creating a downward flow of dense, extremely cold, saline water, with a lower freezing point than the surrounding water. When this plume comes into contact with the neighboring ocean water, its extremely low temperature causes ice to instantly form around the flow. This creates a hollow stalactite, or icicle, referred to as a brinicle.