The desert biome Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm per year. 1/5 = 20%

Types of deserts Desert biomes can be classified according to several characteristics. There are four major types of deserts: Hot and dry Semiarid Coastal Cold

Hot and dry desert The seasons are generally warm throughout the year and very hot in the summer. The winters usually bring little rainfall. The average rainfall ranges from 15 – 26 cm per year. Desert surfaces receive a little more than twice the solar radiation and lose almost twice as much heat at night. Annual temperatures range from 20-25° C. The extreme maximum ranges from °C. Minimum temperatures sometimes drop to -18° C. Most deserts, such as the Sahara of North Africa and the deserts of South Western United States, Mexico and Australia, occuring at low latitudes, they are hot and dry deserts.

Semiarid desert The summers are moderately long and dry, and like hot deserts, the winters normally bring low concentrations of rainfall. Summer temperatures usually average between 21-27° C. It normally does not go above 38° C and evening temperatures are cool, at around 10° C. As in the hot desert, rainfall is often very low and concentrated. The average rainfall ranges from 2-4 cm annually. Montana and Great Basin along with the Nearctic realm make up the semiarid deserts.

Coastal desert The cool winters of coastal deserts are followed by moderately long, warm summers. The average summer temperature ranges from 13-24° C; winter temperatures are 5° C or below. The maximum annual temperature is about 35° C and the minimum is about -4° C. The average rainfall measures 8-13 cm in many areas. The maximum annual precipitation over a long period of years has been 37 cm with a minimum of 5 cm. Coastal deserts generally are found on the western edges of continents near the Tropics of Cancer and Capricorn.

Cold desert These deserts are characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer. The mean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C. The winters receive quite a bit of snow. The mean annual precipitation ranges from cm. Annual precipitation has reached a maximum of 46 cm and a minimum of 9 cm. In some areas, rainfall can be heavy in autumn. Cold deserts are also known as polar deserts. Antarctica is the earth's largest cold desert, and the Arctic is the second largest.

Armadillo Lizard Banded Gila Monster Coyote Desert Bighorn Sheep

Barrel Cactus Brittle Bush Chainfruit Cholla Creosote Bush Crimson Hedgehog Cactus Desert Ironwood Joshua Tree Jumping Cholla Mojave Aster Ocotillo Palo Verde Pancake Prickly Pear Cactus Saguaro Cactus Soaptree Yucca Triangle-leaf Bursage

LIFE IN DESERTS – HEALTH ISSUES A desert is a hostile, deadly environment for humans. In hot deserts, high temperatures cause rapid loss of water due to sweating, and the absence of water sources. Dehydration and death can appear within a few days. Humans have to adapt to sandstorms in some deserts, not just in their adverse effects on respiratory systems and eyes. Sandstorms can last for hours, even days. Surviving in the desert is difficult for humans. Despite this, some cultures have made hot deserts their home for thousands of years. Modern technology, including advanced irrigation systems, desalinization and air conditioning have made deserts much more hospitable. In cold deserts, hypothermia and frostbite are the chief hazards, as well as dehydration in the absence of a source of heat to melt ice for drinking. Starvation is also a hazard; in low temperatures the body requires much more food energy to maintain body heat and to move. Most traditional human life in deserts is nomadic in hot deserts on finding water. In cold deserts, it depends on finding good hunting and fishing grounds, and on storing enough food for winter. Permanent settlement in both kinds of deserts requires permanent water and food sources and adequate shelter, or the technology and energy sources to provide it. The danger represented by wild animals in deserts has been featured in explorers' accounts but does not cause higher rates of death, and generally does not by itself affect human life. Defense against polar bears may be advisable in some areas of the Arctic, as may precautions against venomous snakes and scorpions in choosing sites at which to camp in some hot deserts.