Freezing rain - that's something new. It looks very nice, of course, but it's not
good. A lot of wires were torn in
Moscow. Airports Domodedovo and Sheremetevo were closed. About 100,000 people
in Moscow region were left without electricity, water or heating.
And the fact that fallen trees are lying everywhere... Thousands trees fell
over under the weight of ice. It's terribly.
Freezing rain is called the rain that falls when surface temperature is below
freezing. Unlike sleet, a mixture of rain and snow that forms ice pellets, or
hail, freezing rain is made entirely of liquid droplets. The raindrops become
supercooled while passing through a sub-freezing layer of air hundreds of meters
above the ground, and then freeze upon impact with any surface they encounter,
including the trees, ground, automobiles, and electrical wires. The resulting
ice, called glaze, can accumulate to a thickness of several centimeters and
cover all exposed surfaces.
Freezing rain often causes major power outages by forming glaze ice. When the
freezing rain or drizzle is light and not prolonged, the ice formed is thin.
When large quantities accumulate, however, it is one of the most dangerous types
of winter hazard. When the ice layer exceeds approximately 6.4 mm (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 and lightning 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 freezing rain does not hit
the ground as an ice pellet (called "sleet") but still as a rain droplet, it
conforms to the shape of the ground, or object such as a tree branch or car.
This makes one thick layer of ice, often called "glaze".
Freezing rain is considered to be 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
freezing rain can overwhelm even the most sophisticated deicing systems on large
Freezing rain - Wikipedia