Death Valley Still The Hottest Spot On Earth
September 13, 2012

Highest Temperature Goes Back To Death Valley

Lee Rannals for - Your Universe Online

Meteorologists have ended an 80-year debate over where and what the hottest temperature ever recorded on Earth was.

Back in the summer of 1913, temperatures soared to a scorching 134 degrees Fahrenheit in Death Valley, California, setting a record as the world's hottest temperature.

However, less than 10 years later, on September 13, 1922, reports came in of a 136.6 degree Fahrenheit temperature being recorded in El Azizia, Libya.

There have always been skeptics of the Libyan temperature, leading meteorologists to do a little research to find out if the 136.6 degree temperature reading was inaccurate.

After determining that the Libya temperature had some errors, the World Meteorological Organization (WMO) has today accepted the Death Valley, California temperature as the most extreme ever recorded.

"We found systematic errors in the 1922 reading," according to Randy Cerveny, an Arizona State University President's Professor in the School of Geographical Sciences and Urban Planning. "This change to the record books required significant sleuthing and a lot of forensic records work," added Cerveny, who also is the Rapporteur of Climate and Weather Extremes for the WMO, the person responsible for keeping worldwide weather records.

The "new" world record temperature was recorded on July 10, 1913 at Greenland Ranch in Death Valley, California.

"In the heart of every meteorologist and climatologist beats the soul of a detective," Cerveny said.

He said the El Azizia temperature had long been in question because it was recorded in 1922 at what was an Italian army base back then.

The team identified five major concerns with the El Azizia temperature record during their research, including the use of antiquated instrumentation, an inexperienced observer, an observation site not representative of desert surroundings, poor matching of the extreme to nearby locations, and poor matching to subsequent temperatures recorded at the site.

The committee concluded that the most compelling scenario for the 1922 temperature was that a new and inexperienced observer, who was not trained in the use of an unsuitable replacement instrument, improperly recorded the observation.

The meteorologists found and examined the original log sheet, which Cerveny said was very useful. He said there was a person new to making temperature measurements using a "Six-Bellini thermometer," which at the time was considered an obsolete piece of technology.

After reviewing the logs, they determined that the person who recorded the temperature was transposing what he read from the thermometer, scoring the readings in the wrong column of the log.

"One of the problems with a Six-Bellini thermometer is that the indicator–the pointer–to the temperature scale could conceivably be read at the top of the pointer or the bottom of the pointer," Cerveny explained. "If an inexperienced observer used the top of the pointer rather than the bottom, he would have been as much as 7 Celsius (12 Fahrenheit) in error."

Other forensic information giving the record back to the 1913 event included the general location of where the measurement was made. El Azizia is about 35 miles southwest of Tripoli, which is on the Mediterranean coast.

"When we compared his observations to surrounding areas and to other measurements made before and after the 1922 reading, they simply didn't match up," Cerveny said in the release.

He said that the world record highest temperature does have some important uses, because the data can help cities to design buildings that are best suited for these extreme temperatures. Knowing the maximum temperatures materials can endure leads to better designs.

"This investigation demonstrates that, because of continued improvements in meteorology and climatology, researchers can now reanalyze past weather records in much more detail and with greater precision than ever before," Cerveny said in the release. "The end result is an even better set of data for analysis of important global and regional questions involving climate change."

Image 2 (below): This is a drawing of the Six-Bellini thermometer. Credit: Image supplied by Paolo Brenni, President of the Scientific Instrument Commission, and courtesy of Library of the Observatorio Astronomico Di Palermo, Gisuseppe S. Vaiana.