When a meteorologist says the snow level could drop to 1,500 feet, what does that mean to you? What's the elevation where you live or where you're traveling?

The El Niño is an age-old phenomenon that occurs in cycles in the Pacific Ocean.

"The greenhouse effect" is a popular term for the role that carbon dioxide, water vapor and trace gases play in keeping the Earth's surface warmer than it would be without their presence.

Just what is the jet stream? In the early days of meteorology, no one had ever heard of the jet stream. But these days we see it represented almost every night on the TV news. Well, it was just about 50 years ago that this important weather phenomena was discovered and verified.

The "Northern Lights," also knows as the "Aurora Borealis," is a brilliant display of shimmering blues, greens, yellows and reds observed across the northern sky. The effect may last for only a few minutes, or it could last for a period of days.

The Fujita Tornado Scale, or F-Scale, was developed by Dr. Theodore Fujita. It classifies tornadoes based on the damage caused:

Although they are popularly called tidal waves, tsunamis have nothing to do with the tides.

Weather Glossary

How cold is it? The temperature of the air is not always the most reliable indicator of just how chilly you will feel during cold weather. Other weather elements, such as wind speed, relative humidity and cloud cover, also have an influence. In addition, the kind of clothing you are wearing and the state of your health play an important role. But one of the most important factors is wind.

The Beaufort Wind Scale for estimating wind speed was developed in 1805 by Admiral Sir Francis Beaufort. It was originally used for estimating wind velocity by noting the effects of winds an the sails of British Navy sailing ships. It was found to be so valuable that it was later modified for use on land.