Typical sheet ice refers to ice formed through a rapid freezing effect. They appear in a smooth, thin layer usually on water or wet surfaces. In other words, sheet ice completely covers the surface waters by thin layer ice pellets.
The Formation of Sheet Ice
As temperature continually goes down, the ice gradually grows thicker. Hence, sheet ice forms from the combination of different forms of ice pellets over an extended period. Sheet ice varies in size depending on the surface area of the body of water covered. The more massive sheet ice can cover as much as 20,000 square miles of water surfaces.
According to the type of combined ice which makes up the entire covering, sheet ice has the following different types.
Pancake sheet ice
Pancake sheet ice has pellets rounded in shape and a diameter ranging from 30 centimeters to 3 meters. The diameter depends on the steady temperature of the area over a period. The thickness varies and could be as much as 10 centimeters
The unique thing about the pancake ice pellets is the elevated rims. These are formed by the piling of smaller pieces up the edges when they collide giving it a pancake look. These rims are used to detect the early formation of the pancake ice from smaller ice pieces. When the sheet ice fully forms, there is still a continuous flow of water under the sheet. At points where there is slightly warmer water, it causes the ice to thin out. Thin ice leaves spots where it becomes possible to fall through.
Shelf type sheet ice
Shelf sheet ice includes ice sheets floating permanently on water surfaces. They are extensions from icy land masses. These masses flow slowly to the sea after their break away from the more massive glaciers or ice streams. If no melting occurs during the time of floating, they eventually grow into larger and thicker ice masses. They are usually without a distinct feature.
Here are the groups of sheet ice according to size and thickness.
Brash Ice: Floating ice fragments which accumulate to form this sheet ice do not exceed 2 meters in thickness. The pieces are pure wreckage from other forms of ice.
Floe: This includes flat ice pieces with a surface area that range from 20 meters and more. Floes are subdivided according to the horizontal extent as follows:
- Giant: Greater than 10 km across
- Medium: 100-500 m across
- Vast: 2-10 km across
- Big: 500-2,000 m across
- Small: 20-100 m across
Sheet ice comes in different forms and shape. These different shapes are determined, by the fragments which rise on water surfaces such as lakes, rivers, seas, and ocean.
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