Death Valley National Park is famous for being the hottest, driest, and lowest place in the United States. The interesting thing about all these extremes, as I learned during a recent visit, is how they interconnect.
Situated in eastern California near the Nevada border, the park’s topography is known as basin and range. This is where the earth’s crust is rifting apart, creating mountains in some areas and deep basins in others. Death Valley is a long, narrow basin that reaches a depth of 282 feet below sea level. It is also in the rain shadow of four different mountain ranges to the west – the Coastal Range, the Sierra Nevada, the Argus Range, and the Panamint Range.
As storms move inland from the Pacific, they must rise up and over each range. In doing so, they cool and their water vapor condenses into rain or snow that falls on the western side of these mountains. By the time a storm system reaches Death Valley, it has lost most of its moisture. The average annual rainfall in the park, according to NOAA, is just 2.36 inches.
These dry conditions, along with the valley’s below-sea-level elevation, help to produce the park’s famous heat. With cloud free skies and sparse vegetation, a maximum amount of sunlight can reach the ground. The rocks and parched soil absorb the heat and radiate it into the air. The warm air rises but becomes trapped by the steep valley walls. After cooling slightly, it is recycled back toward the valley floor where it is heated even further by atmospheric compression. During the summer months, this process generates hot winds and sizzling temperatures. The average high temperature in the park ranges from 67°F in January to 116°F in July. The hottest temperature ever recorded was 134°F on July 10, 1913 – a world record.
Looking ahead, as the climate changes, the southwestern region of the US is expected to become even hotter and drier. It seems like only a matter of time before Death Valley breaks its own heat record.