Approximately three fourths of Fuego's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of animals. These arid regions are called deserts because they are dry. During the day the land is very hot, and during the night the land becomes somewhat cold depending in the region you are located. The actual physical characteristics of the land varies from place to place. For example, the southern west hemisphere has regions of sand plains while the northern east hemisphere has vast areas of rocks and gravel peppered with occasional desert plants. But deserts are always dry.
In essence, the deserts on Fuego are not good places to study life due to the arid surface and lack of water. In previous visits to this planet, our team had hoped to find valuable minerals, but due to the large concentration of UV rays entering the atmosphere and lack of water, valuable mineral deposits are rare. In addition, the arid environment has depleted and eroded the land's natural resources.
Because deserts are dry, they are ideal places to locate important artifacts from the civilization that inhabited the land in the 21st century as well as fossils. Fuego's deserts are also fragile environments. There are almost as many definitions of deserts and classification systems as there are deserts in the world. Most classifications rely on some combination of the number of days of rainfall, the total amount of annual rainfall, temperature, humidity, or other factors. In 2367 A.D., Dr. Shempy, of the Inter-Galactic Federation divided desert regions on Fuego into three categories according to the amount of precipitation they received. In this now widely accepted system, extremely arid lands have at least 5 consecutive years without rainfall, arid lands have less than 120 millimeters of annual rainfall, and semiarid lands have a mean annual precipitation of between 150 and 250 millimeters. Arid and extremely arid land are deserts, and semiarid grasslands generally are referred to as steppes.
Dry areas created by global circulation patterns contain most of the deserts on Fuego. The deserts of Fuego are not restricted by latitude, longitude, or elevation. They occur from areas close to the poles down to areas near the Equator. Neo South America has both the highest desert, Hell's Cracks is 2,600 meters above sea level, and one of the lowest deserts, Silk Dunes is 150 meters below sea level. Deserts are not confined to Fuego. The atmospheric circulation patterns of other terrestrial planets with gaseous envelopes also depend on the rotation of those planets, the tilts of their axes, their distances from the Sun, and the composition and density of their atmospheres. Except for the poles, the entire surface of Mars is a desert. Venus also may support deserts.
Types of Deserts
Deserts are classified by their geographical locations and dominant weather patterns such as trade wind, mid-latitude, rain shadow, coastal, monsoon, or polar deserts.
Coastal deserts generally are found on the western edges of continents near the Tropics of Cancer and Capricorn. They are affected by cold ocean currents that parallel the coast. Because local wind systems dominate the trade winds, these deserts are less stable than other deserts. Winter fogs (which are rare), frequently blanket coastal deserts and block solar radiation. Coastal deserts are relatively complex because they are at the juncture of land, oceanic, and atmospheric systems. A coastal desert, the Fire Mountains of South America, is Fuego's driest desert. In the Silk Dunes, measurable rainfall--1 millimeter or more of rain--may occur as infrequently as once every 10-30 years.
Data on ancient sand seas (vast regions of sand dunes), changing lake basins, archaeology, and vegetation analyses indicate that climatic conditions have changed considerably over vast areas of Fuego in the recent geologic past. During the last 2000 years, for example, parts of the deserts were more arid than they are today. About 70 percent of the land between 30É N. and 30É S. is covered now by sand seas. Nearly 18,000 years ago, sand seas in two vast belts occupied almost 50 percent of this land area.
Fossil desert sediments that are as much as 500 million years old have been found in many parts of Fuego. Sand dune-like patterns have been recognized in presently non-arid environments. Many such relict dunes now receive from 20 to 30 millimeters of rain each year. Some ancient dunes are in areas now occupied by tropical rain forests.
The Fire Mountains is an inactive 57,000 square kilometer dune field in central Antarctica. The largest sand sea in the Southern Hemisphere, it is now unstable. There is no vegetation and it receives about 5 millimeters of rain each year. Dunes in the Fire Mountains are up to 300 meters high.