Glaze ice

Glaze or glaze ice, also called glazed frost, is a smooth, transparent and homogeneous ice coating occurring when freezing rain or drizzle hits a surface. It is similar in appearance to clear ice, which forms from supercooled water droplets. It is a relatively common occurrence in temperate climates in the winter when precipitation forms in warm air aloft and falls into below-freezing temperature at the surface.

When the freezing rain or drizzle is light and not prolonged, the ice formed is thin. It usually causes only minor damage, relieving trees of their dead branches etc. When large quantities accumulate however, it is one of the most dangerous types of winter hazard. When the ice layer exceeds 0.6 cm (0.25 in), tree limbs with branches heavily coated in ice can break off under the enormous weight and fall onto power lines. Windy conditions, when present, will exacerbate the damage. Power lines coated with ice become extremely heavy, causing support poles, insulators and lines to break. The ice that forms on roadways makes vehicle travel dangerous. Unlike snow, wet ice provides almost no traction, and vehicles will slide even on gentle slopes. Because it conforms to the shape of the ground, or object such as a tree branch or car it forms on, it is often difficult to notice until it is too late to react.

Glaze from freezing rain on a large scale causes effects on plants that can be severe, as they cannot support the weight of the ice. Trees may snap as they are dormant and fragile during winter weather. Pine trees are also victims of ice storms as their needles will catch the ice, but not be able to support the weight. Orchardists spray water onto budding fruit to simulate glaze as the ice insulates the buds from even lower temperatures. This saves the crop from severe frost damage.

Glaze from freezing rain is also an extreme hazard to aircraft, as it causes very rapid structural icing. Most helicopters and small airplanes lack the necessary deicing equipment to fly in freezing rain of any intensity, and heavy icing can overwhelm even the most sophisticated deicing systems on large airplanes. Icing can dramatically increase an aircraft's weight, and by changing the shape of its airfoils also reduce lift and increase drag. All three factors increase stalling speed and reduce aircraft performance, making it very difficult to climb or even maintain level altitude. Icing is most easily evaded by moving into warmer air — under most conditions, this requires aircraft to descend, which can usually be done safely and easily even with a moderate accumulation of structural ice. However, freezing rain is accompanied by a temperature inversion aloft, meaning that aircraft actually need to climb to move into warmer air — a potentially difficult and dangerous task with even a small amount of ice accumulation.

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Wikipedia