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Tahoe Nugget #191:

Sierra Soaring Record
September 30, 2010

Meteorologists call it "The Monster." It's the powerful mountain lee wave that forms to the east of the Sierra Nevada in the Owens Valley of California. It is a visually stunning region that contrasts the rugged granite ridgeline of the High Sierra with a low desert valley that is protected from the severe storms that frequently rage in the upper elevations.

The Sierra towers to the west, but the majestic White-Inyo Mountains stand tall just to the east. Both mountain ranges boast peaks 10,000 feet above the valley floor, and are separated by only 20 miles.

1 Nugget #191 Owen Valley Bishop
Bishop is located in the heart of the Owens Valley.

Mountain lee waves form downwind of many mountain ranges around the world, but the powerful lift exhibited by the Sierra Wave is unusual in its force. The lee wave itself is invisible, but a sure sign of its presence are lenticular clouds, also known as wave clouds, commonly observed when the jet stream is in close proximity during the winter and spring months.

Lenticular clouds form downwind from where air flows up and down over mountain peaks and troughs. It is an unusual, distinct cloud, with a smooth, layered appearance, a flat bottom, and the curved upper surface of an airplane wing.  Similar to a flowing stream's ripple, lenticular clouds appear stationary, but air passes through them at speeds from 50 to 100 miles per hour.

2 Nugget #191 Tahoe Lenticular
Lenticular cloud forming over Lake Tahoe.

The same topographic features that make Owens Valley such a photogenic tableau also generate powerful forces in the atmosphere that create an extraordinary lee wave, a phenomenon that has attracted sailplane pilots from California and around the world. The region has also become a focal point for scientists attempting to better understand the atmospheric dynamics of wave clouds and their formidable sister, the dangerous, turbulent rotors that form at the surface.

In 1947, two pilots from Bishop, California, began a flying service in the area and soon were spending much of their time exploring the dynamics of the Bishop Wave, as it was initially called. In 1950, one of the pilots flew his P-38 powered aircraft into the Bishop Wave, cut the engines and feathered the propellers. Instead of plummeting to his death, he "soared" for more than an hour on the powerful lift. Soon after, the U.S. Air Force started the Sierra Wave Project, a research program based in Bishop. The military was assisted by the University of California — Los Angeles (UCLA), and the Southern California Soaring Association (SCSA).

3 Nugget #191 Tahoe from Glider
Photo of Lake Tahoe by glider pilot Steve Streitmatter.

Among the representatives from UCLA was Harold "Hal" Klieforth, a 23-year-old mountain meteorology graduate student. Klieforth had been drafted into the military during the summer of 1945 and at one point had had the opportunity to watch an Air Force meteorology officer create detailed weather maps before a scheduled flight. Fascinated with weather and aviation, he entered UCLA to study meteorology. After graduation, Klieforth became UCLA's Wave Project scientist and field representative based full-time in Bishop.

One of the key tools the researchers used to develop an understanding of the mountain wave was instrumented sailplanes, which were considered significantly better than powered aircraft for the study. Fuel was a limitation for internal combustion engines and the absence of an engine simplified how to determine the aircraft's influence upon the data being measured. Over the next few years, the scientists steadily improved their primitive two-seat sailplanes as they sent their teams higher and higher into the atmosphere. The planes had a self-contained oxygen system, but the cockpits were not pressurized.

4 Nugget #191 Shoreline Detail Glider
Pilot Streitmatter took this photo of Tahoe's shoreline. Note boats on buoys.

Technology made the ascents into the stratosphere possible, but the severe cold during the long-duration, high-altitude flights caused problems. Outside temperatures as low as 105 degrees below zero Fahrenheit were recorded, with a minus 50 degrees once measured on the interior instrument panel. The brutal temperatures inflicted varying degrees of frostbite on the feet of every pilot and crew, and at one point every flight member was limping.

As the project progressed, flights started to regularly exceed 40,000 feet, until finally, on March 19, 1952, a sailplane manned by team members Hal Kleiforth and Larry Edgar set a world record for the highest flight in a two-man glider (44,255 feet in an unpressurized cockpit). In 2009, the recently deceased millionaire pilot Steve Fossett flew a glider high above the Andes Mountains to set the current World Altitude Record of 50,699 feet.

Hal Klieforth is a friend and colleague of mine, and at 83 years of age he's still going strong with his scientific research in the Owens Valley, where he climbs mountains, installs remote weather stations, and is organizing his weather and climate research library in Bishop. He spends his free time rambling about the terrain, filling his notebook with observations about weather, glaciers, flora and fauna. After decades of research, from cloud seeding to the timing of each year's spring bloom, Hal believes that his boxes of notebooks crammed with observations will yield value in the context of climate change in the High Sierra. 

5 Nugget #191 Klieforth Bishop Window 10-08
Hal Klieforth contemplates his beloved Sierra.

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