Generally, the farther from the equator you travel, the colder the temperatures and the more likely it is that you will encounter snow. Of course, that's not always the case. Snowfall is related to a number of factors, including temperature, moisture availability and elevation above sea level. Since Seattle is on the northwest coast of the U.S., there is plenty of moisture available from the Pacific Ocean, but the average snowfall is only about 14 in. Cold air moving down from CAnada and Alaska does not usually spread west to the Pacific coast. The Rocky Mountains and the Cascades Ranges keep the bulk of the cold air over the northcentral and norteastern U.S. So the cold air is not in place when precipitation arrives. Chicago is colder than Seattle but far from oceanic sources of moisture. The average annual snowfall for Chicago is about 38 in. Because Boston is adjacent to the Atlantic Ocean and is often affected by cold air out-breaks during the winter, it receives somewhat more snow than Chicago (about 42 in.). Even though Salt Lake City is about 600 miles from the Pacific Ocean and is further south than Seattle, Chicago or Boston, it gets about 55 in. of snowfall during an average year. Salt Lake City has an elevation of 4200 ft. above sea level, whereas the other cities listed above are very close to the level of the sea. As a result, most of the time during the winter months when precipitation falls, the higher elevations dictate that it will be in the form of snow. When the air is moist the temperature drops about 3 degrees F for every thousand feet of elevation. Sometimes however, even with high elevations and cold air there is not much snow. The South Pole is over 9,000 ft above sea level and only gets about 25 in. of snow a year. The reason for this is that there is virtually no moisture available in the extremely dry polar air. The South Pole is near the center of Antarctica and so along way from moisture sources. In theory it is never too cold to snow, but as temperatures get colder and colder there is less and less water vapor in the air. However, whatever snow does fall at the South Pole doesn't melt. That's why the elevation is approachig 10,000 ft. Since 1957, when temperatures were first recorded, only two times has the temperature at the South Pole been above 0 degrees F.

Most of the places that normally get snow during the winter have already received their first snowfall. - Rank the following list of places according to annual snowfall amounts; Salt Lake City, Seattle, Chicago, Boston and the South Pole.

12/01/95