It's Raining Fish and Spiders (21 page)

used by permission of James Quirk; taken by his grandfather.

As the low moves eastward, a cold front trails south from it. Warm air is ahead of the front. As the low works eastward through the south, it produces soaking rains and thunderstorms while picking up tons of moisture from the Gulf of Mexico. When that moisture moves north and hits colder air, it produces snow through Tennessee, Kentucky, and the Ohio Valley.

By midnight Monday, the low is over Atlanta, and thunderstorms are dumping heavy rain over Georgia, South Carolina, and Florida. As the warm front pushes northward into the colder air, snow breaks out over the mid-Atlantic states, the Smokey Mountains, and the Virginias. By noon Tuesday, the low is over Washington, D.C., producing snow, and the arctic high is sliding eastward over New England.

Now the low is moving northeastward and out over the Atlantic Ocean, where conditions cause the low to strengthen. As the low becomes stronger it throws more moisture from the ocean back into the northeastern United States, creating a major snowstorm. In this scenario as much as 20 to 30 inches of snow can be produced throughout New England and the other northeastern states. By midnight Tuesday, the storm is just east of Boston.

Types of Winter Precipitation

In winter, one of the hardest things for a weather forecaster to do is to figure out what type of precipitation there will be. In most cases winter storms bring more than just snow. Only in the coldest months in the northernmost reaches of the country is the precipitation usually all snow. Over much of the country, depending on local geography and the flow of just a little warm air, precipitation can vary from snow, sleet, or freezing rain (which causes many more automobile accidents than snow). Sometimes it is hard for forecasters to say exactly what is going to fall from the sky in winter because it's not just snow.

Other Kinds of Ice

Frank Picini

There is always confusion when it comes to the names of the types of ice falling from the sky. Many people confuse sleet with hail. The difference is easy to remember: sleet in winter and hail in summer. But when it comes to ice and its classifications, not even scientists can agree.

Snow makes up seven of the ten kinds of frozen precipitation in the international classification system. The others are graupel, hail, and ice pellets or sleet. Official weather observers in the United States use the term
ice pellets
rather than sleet, as sleet is defined differently throughout the world. Here you can see the differences.

National Oceanic and Atmospheric Administration/Department of Commerce

Wind Chill!

Whenever you hear the words “wind chill,” it's because the cold winds are cranking outside. Wind chill is actually how skin feels when exposed to bitter winter winds. Updated in 2001 by the National Weather Service, the Wind Chill Temperature Index uses science, technology, and computer modeling to derive the Wind Chill Chart, which lets you know how it really feels outside.

National Oceanic and Atmospheric Administration/Department of Commerce

The chart is based on the model of a human face, with wind blowing at an average height of 5 feet (the average height of an adult human face) and measures temperature against wind speed. Wind chill is computed using modern heat transfer theory (heat loss from the body to its surroundings during cold and breezy or windy days). Impact from the sun is not factored in as that may increase wind-chill temperatures by 10° to 18°F (-12° to -8°C). Wind chill can only be figured for temperatures at or below 50°F (10°C) and wind speeds above 3 mph.

You've Got to Be Kidding Me—Antarctica!

You want to talk about extremes, Antarctica is the land of extremes! It is the
coldest, windiest,
and
highest
continent anywhere on Earth! The lowest temperature ever recorded on the planet was -128.6ºF (-89.2°C), was measured at the Russian research station of Vostok, near the South Pole, at an elevation of 11,220 feet. That's the same height as the Wasatch Mountains in Utah.

United States Antarctic Program, National Science Foundation; Photographer: Jerrod Clausen

Bill Adler; used by permission.

Bill Adler; used by permission.

Antarctica has an average elevation of 7,544 feet (2,300 meters) above sea level. Even though it is covered in ice, it receives almost the least amount of rainfall of any place in the world, getting just slightly more rainfall than the Sahara Desert. Despite the snow and ice, Antarctica is the
largest desert
on Earth.

On July 4, 2003, a remote-recording weather station located on Queen Maud Land in eastern Antarctica reported an air temperature of -94°F (-70°C) and a wind speed of 75 mph. The resulting wind chill of -150°F (-101°C) is perhaps the coldest ever recorded anywhere. It's difficult to even imagine how a human could endure such extreme conditions!

Bill Adler; used by permission.