Black ice

Black ice, sometimes called clear ice, refers to a thin coating of glaze ice on a surface, especially on roads. The ice itself is not black, but virtually transparent, allowing the often black road below to be seen through it. The typically low levels of noticeable ice pellets, snow, or sleet surrounding black ice means that areas of the ice are often practically invisible to drivers or persons stepping on it. There is, thus, a risk of skidding and subsequent accident due to the unexpected loss of traction. A similar problem is encountered with diesel fuel spills on roads.

Definitions

The term black ice in the United States is often incorrectly used to describe any type of ice that forms on roadways, even when standing water on roads turns to ice as the temperature falls below freezing. Correctly defined, black ice is formed on relatively dry roads, rendering it invisible to drivers. It occurs when in the textures present in all pavements very slightly below the top of the road surface contain water or moisture, thereby presenting a dry surface to tires until that water or moisture freezes and expands; drivers then find they are riding above the road surface on a honeycombed invisible sheet of ice.

Black Ice (book)

Black Ice is the fifth book written by Becca Fitzpatrick. It is told from Britt's point of view as Britt, her friend Korbie, Korbie's brother Calvin, and their friend Bear set off to go backpacking in the mountains for spring break. But all goes wrong when an unexpected snowstorm stops them from reaching the cabin.

Characters

Britt Pfeiffer Britt is the protagonist of the book, a high school student who is Calvin's ex-girlfriend, but finds herself romantically interested in her kidnapper, Jude Van Sant.

Jude Van Sant Known as Mason or Ace in the beginning of the book. Later becomes Britt's love interest. Also brother of Lauren Huntsman.

Calvin Versteeg

Shaun

Korbie

Ian

Congelation ice

Congelation ice is ice that forms on the bottom of an established ice cover.

Seawater

On seawater, congelation ice is ice that forms on the bottom of an established sea ice cover, usually in the form of platelets which coalesce to form solid ice.

Only the water freezes to ice, the salt from the seawater is concentrated into brine, some of which is contained in pockets in the new ice. Due to the brine pockets, congelation ice on seawater is neither as hard nor as transparent as fresh water ice.

Fresh water

On the surface of lakes, or other bodies of still freshwater, congelation ice is often called black Ice. This ice has frozen without many air bubbles trapped inside, making it transparent. Its transparency reveals the colour, usually black, of the water beneath it, hence the name. This is in contrast to snow ice, sometimes called slush ice, which is formed when slush (water saturated snow) refreezes. Snow ice is white due to the presence of air bubbles.

Black ice grows downward from the bottom of the existing ice surface. The growth rate of the ice is proportional to the rate that heat is transferred from the water below the ice surface to the air above the ice surface. The total ice thickness can be approximated from Stefan's equation.