Death Valley is a desert located in the southwestern United States. It is the lowest, driest, and hottest location in North America. Badwater, a basin located within Death Valley, is the specific location of the lowest elevation in North America at 282 ft (85.5 m ) below sea level. This point is only 76 miles (123 km) east of Mount Whitney, the highest point in the contiguous United States. Death Valley holds the record for the highest reliably reported temperature in the Western hemisphere, 134°F (56.7°C) at Furnace Creek in 1913—just short of the world record, which was 136°F (58°C) in Al 'Aziziyah, Libya, on September 13, 1922.

Located on the border between California and Nevada, in the Great Basin and the Mojave Desert, southeast of the Sierra Nevada mountains, Death Valley constitutes much of Death Valley National Park and is the principal feature of the Mojave and Colorado Deserts Biosphere Reserve. It is located mostly in Inyo County, California. It runs from north to south between the Amargosa Range on the east and the Panamint Range on the west; the Sylvania Mountains and the Owlshead Mountains form its northern and southern boundaries, respectively. It has an area of about 3,000 sq mi (7,800 km2). Death Valley shares many characteristics with other places around the world that lie below sea level.

Geology

Death Valley is one of the best geological examples of a basin and range configuration. It lies at the southern end of a geological trough known as Walker Lane, which runs north into Oregon. The valley is bisected by a right lateral strike slip fault system, represented by the Death Valley Fault and the Furnace Creek Fault. The eastern end of the left lateral Garlock Fault intersects the Death Valley Fault. Furnace Creek and the Amargosa River flow through the valley but eventually disappear into the sands of the valley floor.

Death Valley also contains salt pans. According to current geological consensus, during the middle of the Pleistocene era there was a succession of inland seas (collectively referred to as Lake Manly) located where Death Valley is today. As the area turned to desert the water evaporated, leaving behind the abundance of evaporitic salts such as common sodium salts and borax, which were subsequently exploited during the modern history of the region, primarily 1883 to 1907.

As a general rule, lower altitudes tend to have higher temperatures where the sun heats the ground and that heat is then radiated upward, but as the air begins to rise it is trapped by (1) the surrounding elevation and (2) the weight of the air (essentially the atmospheric pressure) above it. The atmospheric pressure is higher at very low altitudes than it is under the same conditions at sea level because there is more air (more distance) between the ground and the top of the atmosphere. This pressure traps the heat near the ground, and also creates wind currents that circulate very hot air, thereby distributing the heat to all areas, regardless of shade and other factors.

This process is especially important in Death Valley as it provides its specific climate and geography. The valley is surrounded by mountains, while its surface is mostly flat and devoid of plants, and of which a high percentage of the sun's heat is able to reach the ground, absorbed by soil and rock. When air at ground level is heated, it begins to rise, moving up pass steep high mountain ranges, which then cools slightly sinking back down towards the valley more compressed. This air is then reheated by the sun to a higher temperature moving up the mountain again, whereby the air moves up and down in a circular motion in cycles similar to how a convection oven works, albeit a natural one. This superheated air increases ground temperature markedly, forming the hot wind currents that are trapped by atmospheric pressure and mountains thus stays mostly within the valley. Such hot wind currents contribute to perpetual drought like conditions in Death Valley and prevent much cloud formation to pass through the confines of the valley, where precipitation is often in the form of a virga. Death Valley holds temperature records because it has an unusually high number of factors that lead to high atmospheric temperatures.

Climate

The depth and shape of Death Valley influence its summer temperatures. The valley is a long, narrow basin 282 feet (86 m) below sea level, yet is walled by high, steep mountain ranges. The clear, dry air and sparse plant cover allow sunlight to heat the desert surface. Heat radiates back from the rocks and soil, then becomes trapped in the valley's depths. Summer nights provide little relief as overnight lows may only dip into the 86°F to 95°F (30°C to 35°C) range. Heated air rises, yet is trapped by the high valley walls, is cooled and recycled back down to the valley floor. These pockets of descending air are only slightly cooler than the surrounding hot air. As they descend, they are compressed and heated even more by the low elevation air pressure. These moving masses of super heated air blow through the valley creating extreme high temperatures.  The hottest air temperature ever recorded in Death Valley (Furnace Creek) was 134°F (57°C) on July 10, 1913, also that same year saw Death Valley's coldest temperature, on January 8 the temperature dropped to 67°F (20°C) at Furnace Creek. During the heat wave that peaked with that record, five consecutive days reached 129° F (54°C) or above. The greatest number of consecutive days with a maximum temperature of 100° F or above was 154 days in the summer of 2001. The summer of 1996 had 40 days over 120° F, and 105 days over 110° F.  .................................................................................................................................................................................

During very wet periods, such as the winter of 1995, the Amargosa River can flow at the surface, even forming a temporary lake at Badwater.

From 1961-2008 the weather station at Death Valley (Furnace Creek) recorded an average yearly temperature of 76.7°F (24.8°C) with an average high in January of around 66°F (19°C) and 116°F (47°C) in July. However another weather station located in Death Valley (Cow Creek), during the period from 1934 to 1961 recorded an average yearly temperature of 77.3°F (25.2°C) with an average high in January of around 64°F (18°C) and 116°F (47°C) in July. 

The period from July 17-19, 1959 was the longest string of consecutive days where night time low temperatures did not drop below 100°F. As recently as 2003 the Furnace Creek weather station reported two consecutive readings with night time lows of 100°F or above. The highest ever night time low temperature in Death Valley was 103°F recorded on July 5, 1970 and July 24, 2003.

The longest stretch of consecutive days where temperatures reached 90°F (32°C) or more was 205 during Apr-Oct 1992. On average there are 192 days per year in Death Valley where temperatures reach 90°F (32°C) or more. 

The average annual precipitation in Death valley (Greenland Ranch Station) is 1.58 inches (4.00 cm). The wettest month on record is January 1995 when 2.59 inches (6.57 cm) fell on Death Valley.

Weather averages for Death Valley (Furnace Creek Station)  Temperatures in Fahrenheit

Lake Badwater and Glacial Lake Manly

In 2005, Death Valley received 4 times its average annual rainfall of 1.5 inches. As it has done before for hundreds of years, the lowest spot in the valley filled with a wide, shallow lake, but the extreme heat and aridity immediately began sucking the ephemeral lake dry. This pair of images from NASA’s Landsat 5 satellite documents the short history of Death Valley’s Lake Badwater: formed in February 2005 (top) and long gone by February 2007 (bottom). In 2005, a big pool of greenish water stretched most of the way across the valley floor. By May of 2005 the valley floor had resumed its more familiar role as Badwater, a salt-coated playa. In time, this freshly dissolved and recrystallized salt will darken. The western margin of Death Valley is traced by alluvial fans. During flash floods, rainfall from the steep mountains to the west pours through narrow canyons, picking up everything from fine clay to large rocks. When these torrents reach the mouths of the canyons, they widen and slow, branching out into braided streams. The paler the fans, the younger they are. During the Pleistocene ice age, which ended roughly 10,000-12,000 years ago, the Sierra Nevada ranges were much wetter. During that time, Death Valley was filled with a huge lake, called Glacial Lake Manly, that was nearly 100 miles long and 600 feet deep. History Death Valley is home to the Timbisha tribe of Native Americans, formerly known as the Panamint Shoshone, who have inhabited the valley for at least the past 1000 years. The Timbisha name for the valley, tümpisa, means "rock paint" and refers to the red ochre paint that can be made from a type of clay found in the valley. Some families still live in the valley at Furnace Creek. Another village was located in Grapevine Canyon near the present site of Scotty's Castle. It was called maahunu in the Timbisha language, the meaning of which is uncertain, although it is known that hunu is "canyon"..................................................................................................................................................................

Lake Badwater, February 9, 2005. Landsat 5 satellite photo. Badwater dry lake, February 15, 2007. Landsat 5 satellite photo.

The valley received its English name in 1849 during the California Gold Rush. It was called Death Valley by prospectors and others who sought to cross the valley on their way to the gold fields, even though only one death in the area was recorded during the Rush. During the 1850s, gold and silver were extracted in the valley. In the 1880s, borax was discovered and extracted by mule-drawn wagons.

Death Valley National Monument was proclaimed on February 11, 1933 by President Hoover, placing the area under federal protection. In 1994, the monument was redesignated as Death Valley National Park, as well as being substantially expanded to include Saline and Eureka Valleys.

Greater Roadrunner at Death Valley National Park Visitor Center, California	Zabriskie Point at sunrise in Death Valley.	Sand dunes in Death Valley
	Sometimes after winter rains, Death Valley does not look like a desert for a few weeks.

More information http://en.wikipedia.org/wiki/Death_Valley_National_Park