Winter storms bring not only snow, but also sleet, freezing rain and a cold rain. Since most forms of precipitation start as snow when leaving the clouds, it is the temperature profile of the air between cloud base and the ground that determines its final form. Sometimes it is just a matter of a few degrees between a cold rain and a crippling snowfall.
Optical phenomena such as rainbows, sun dogs, sun pillars and halos are
made possible by the refraction of sunlight. Refraction occurs when light
is bent when it passes from one medium to another. A common example is
how a pencil appears to be bent when submerged in a glass of water.
Both El Niño and La Niña result from surface water temperatures
in the tropical eastern Pacific Ocean. El Niños occur every 3 to
7 years, while La Niña conditions develop about half as often.
The variability of these tropical water temperatures can have a profound
effect on weather patterns far from the equator.
The "greenhouse effect" is a naturally occurring phenomenon
that keeps the Earth's surface and atmosphere at a comfortable, life-sustaining
temperature. Without this effect, life on Earth would not exist. However,
increasing amounts of carbon dioxide from the burning of oil, gas and
coal are enhancing this natural effect, causing the planet to warm to
levels that cannot be explained by natural variability.
When it's cold enough, you can walk on water - the solid phase of water,
ice, that is. Like most liquids, water becomes denser as it gets colder.
However, unlike most liquids, water becomes less dense as it gets close
to its freezing point. If not for this unique property, bodies of water
would freeze from the bottom up and life on Earth would not be possible.
Capable of lighting up the night sky, a lightning strike is the result
of complex interactions of electrical charges within a thunderstorm. Lightning
can pack an electrical punch of 1 billion volts and can heat the air it
travels through to over 50,000°F - five times the temperature of the
While cold air and warm water are necessary ingredients in the formation
of lake-effect snow in the Great Lakes region, flakes dont fall
unless other conditions are met. When all the elements come together,
intense snowfall rates of 6 inches per hour can result, with lake-effect
snowstorms dumping feet of snow downwind.
From the destructiveness of Hurricane Katrina to tornadoes in the Heartland
to the tsunami that devastated Southeast Asia in 2004, images of devastation
are never far from our TV screens. Those far from the tempests may feel
some satisfaction in choosing homes in safe havens. But not so fast. From
East to West, the USA is a patchwork of danger zones.
More than 1,000 tornadoes affect the USA each year, with many more going unreported. Find out how these monster winds form -- many from supercell thunderstorms -- as well as how to protect yourself from their fury.
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