By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM
Death Valley’s Dangers
One of the most inhospitable places on earth claims lives frequently. Death Valley, Calif., is a desperate place to be, never more than this year, as temperatures have approached the world’s record. Forecasts are for the daily high temperatures to reach 127 degrees F (53.3 C.) this week.
The death of an 11-year old boy in early August, 2009, can serve as an example of the extreme dangers and was the third death that year. The intense heat of summer coupled with little shade and a remote location contribute to the deaths of a few tourists visiting the area every summer. Furthermore, low humidity is often a hidden danger not readily apparent to first-time desert visitors.
The tragedy is quite typical of those in Death Valley National Park. The boy and his mother were stranded in a remote corner of the park when their vehicle became trapped in sand. They survived for five days on bottled water, but the boy finally succumbed in the intense heat as temperatures rose above 110 degrees F (43 C).
Death Valley is actually an elongated rift valley about 130 miles (209 km) long and six to 14 miles (10 to 23 km) wide. Its lowest point is 282 feet (85.5 m) below sea level near Badwater, Calif., making it the lowest site in the Western Hemisphere. The valley runs north and south and is located in southeast central California near the Nevada border.
Death Valley is one of the world’s hottest and driest places. The highest temperature ever recorded in the United States, 134 degrees F (57 C), was recorded thereon July 10, 1913. This temperature is within only 2 degrees F (1 C) of tying the world record of 136 degrees F (58 C) at El Azizia, Libya, in 1922.
Death Valley’s shape and depth influence its summer temperatures. The basin is long, narrow and close to sea level and is walled by high, steep mountain ranges. The clear, dry air and sparse plant cover allow sunlight to heat the desert surface and the high valley walls reduce circulation.
Summer nights in Death Valley may see overnight lows dipping only into the 86 to 95 degrees F (30 to 35 C) range, providing little relief from the heat.
Death Valley is extremely dry precisely because it is bounded by high mountains. Lying in the westerly wind belt, most of the air that crosses the region moves from the Pacific Ocean. Before it reaches the Death Valley depression, however, it must cross the high Sierra Nevada and the Panamint Range.
As the moisture-laden air rises on the west sides of the mountains, it expands and cools in a process called adiabatic cooling and most of its moisture condenses. As the drier air descends along the east sides of the mountains, however, the air warms and the process is one of adiabatic warming. As the air heats, its relative humidity falls rapidly. By the time the air reaches the valley floor, it is not only super-heated, but extremely dry.
As summertime desert temperatures rise, particularly in tropical deserts, the relative humidity normally becomes extremely low. A hot, dry desert wind, like the hot air from a hair dryer, quickly evaporates exposed moisture from skin surfaces. The evaporation process provides a mild temporary cooling effect, leading individuals sometimes not to notice huge losses of fluids.
Dry desert air also affects the lungs of all animals, including humans. Animals breathe in dry air and exhale moist air. Even at rest, the moist lining of the lungs readily gives up moisture in exchange for oxygen. Therefore, strenuous exercise under desert conditions increases losses of fluid through both perspiration and respiration. A healthy adult under these stressful conditions may need to drink three to five gallons (11 to 19 liters) of water daily just to function. For these reasons, most desert-dwelling animals are nocturnal, reducing the loss of body fluids during the heat of the day.
The young boy who died in Death Valley and his mother reportedly had only two dozen 16-ounce bottles of water (three gallons or 11liters) and some food for their camping journey. Three gallons of water were not nearly enough to keep the boy and his mother alive for five days in the searing daytime temperature that reached 113 degrees F (45 C). That the boy’s mother lived is practically a miracle.
The extreme heat in Death Valley this year poses problems for all travelers. A stalled car, for example, can result in a life threatening event, even on a major highway. Travelers beware!
And that is Geography in the News.
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor.
Sources: GITN #778, “Death Valley Alive!” April 29, 2005; GITN 1006 Death in Death Valley, Sept. 11, 2009; and http://www.timesonline.co.uk/tol/news/world/us_and_americas/article6789006.ece