Would-be world travelers

who don't have enough money for trips to 1) the arctic tundra, 2) the Mojave Desert, 3) a sagebrush covered cattle ranch and 4) a lush urban area - have another choice. They can come to Utah.

Utah has diverse climates and weather that hit several extremes, says Dale Stevens, BYU geography professor and weather specialist."Utah is a little more diverse than most states," Stevens said. "We have mountains that are wetter than our valleys, we have deserts and transitional situations."

Of the 15 classifications used (in the modified Koppen system) to describe climates worldwide, four types occur within Utah's boarders.

"Many states only have one or two climates," Stevens said. "If a state is very flat, there is not much chance for different climates, and if there is not much distance between the north and south borders, the whole state falls about the same distance from the equator and the temperature is roughly the same."

According to Utah's Comprehensive Weather Almanac, which Stevens wrote with colleagues Dale Jones and Clayton Brough, Utah's climates can be divided into four categories. The state has areas of desert, steppe, undifferentiated highlands and humid continental-hot summer.

About 33 percent of Utah is true desert. The average annual precipitation (five to eight inches) is less than one half what could annually evaporate from the surface of the earth and area plants. Utah's largest true deserts are Canyonland and the Great Basin area.

Steppe areas, making up about 40 percent of Utah, occur between desert margins and higher mountain regions. Steppelands get eight to 14 inches of precipitation annually, which is still less than half the water that can evaporate from the soil and plant surfaces. Grasses, sagebrush and woody plants grow in Utah's steppe-lands, and feed much of the livestock on Utah's ranches.

Roughly 24 percent of Utah is mountainous regions with an undifferentiated highland climate. Most of these regions have severe winters and cool or cold summers. Some mountain summits have trundra temperatures too cold to allow the growth of trees. These areas may have permanent snowfields.

About 3 percent of Utah, a strip located along the Wasatch front, running from the Idaho border almost to Nephi - is categorized as humid continental-hot summer. Annual precipitation exceeds the amount of water that can evaporate from the soil and plant surfaces.

In this area, when moisture-laden breezes rise to clear the nearby Wasatch Mountains, cold temperatures force air to give up moisture as rain or snow. Industries and communities are concentrated in the humid continental-hot summer portion of the state.

Utah's geography is responsible for much of the state's varied weather, Stevens said.

"Most of Utah's moisture comes from the Pacific, but the Great Salt Lake and lakes like Utah Lake put extra moisture in the air and cause some local `lake effect' storms," he said.

Lake effect snowstorms usually occur when a cold wind moves over the warmer lake. Warm, moist lake air rises to meet the colder air, causing dense clouds that deposit snow downwind. According Utah's Comprehensive Weather Almanac, a 1984 lake effect snowstorm from the Great Salt Lake dropped 18 inches of snow on the Salt Lake Valley, causing $1 million in damage to homes, cars, businesses and utility lines.

"Salt Lake has more lake effect storms than Utah Valley because salt keeps the Great Salt Lake from freezing in the winter," Stevens said. "Utah Lake is frozen now, so we have no lake effect."

Utah's lakes, mountains, industry and auto exhaust all contribute to the temperature inversions that plague Utah during the winter months, Stevens said.

"Normally, temperatures get colder as we get up in the air. With an inversion, it gets warmer as you go up."

Inversions occur when air near the ground loses heat. Warmer air rises to rest on top of cold, heavier air and can be trapped under clouds. Air stagnates at lower elevations. Winter in Utah often means snow covering and high-pressure systems, with stagnant conditions resulting from a lack of wind. With the sun's warming rays reflected or blocked by clouds, Utah temperature inversions can last days or weeks.

The only ways to end an inversion are to increase ground temperature or for strong winds to force air movement.

"It takes a pretty strong wind to do the trick," Stevens said. "The mountains can block some of the wind that would help. Temperature inversions can happen anywhere, but the wind would tend to clear them out faster in a flatter state like Kansas. Inversions are a little more persistent here."

Increased pollution is probably contributing to the length and frequency of Utah's inversions, Stevens said, but he also believes people are more sensitive to the condition because of media attention.

"Utah is in a zone that has very erratic weather changes," he said. "We are far from the ocean. Oceans cool and warm slower than the land, stabilizing coastal temperatures.

"This far inland, the winters can be much colder and the summers much warmer than in most coastal states."

Stevens said Utah falls within "an interplay zone of tropical and arctic air masses, which adds variety to our weather."

But while variety may be the spice of life for many of today's outdoor-loving Utahns, it was a rude surprise for some of Utah's early residents. Parley P. Pratt, an early LDS apostle, described the weather that greeted his group of pioneers, camped in Round Valley, four miles south of the Sevier River, on the morning of Jan. 26, 1850.

"In the morning, we found ourselves so completely buried in snow that no one could distinguish the place where we lay, someone rising began shoveling the others out. This being found too tedious a business, I raised my voice like a trumpet and commanded them to arise; then all at once there was a shaking among the snowpiles, the graves were opened and all came forth! We called this Resurrection Camp."