A new study finds that superbolts of lightning are more likely to strike the closer a storm cloud's electrically charged region is to land or the ocean surface.
These conditions are responsible for the "hot spots" of superbolt lightning over some oceans and tall mountains.
Supercell lightning makes up less than 1% of all lightning, but when it hits, it hits hard. Scientists say that while the average lightning strike contains about 300 million volts, superbolters are 1,000 times more powerful and can cause significant damage to infrastructure and ships.
“Although superbolters represent only a very small percentage of all lightning, they are a fascinating phenomenon,” explained Avichai Ephraim, a physicist at the Hebrew University of Jerusalem and lead author of the study.
A 2019 report found that supercell lightning tends to cluster over the northeastern Atlantic Ocean, the Mediterranean Sea, and the Altiplano region of Peru and Bolivia, one of the tallest plateaus on Earth.
“We wanted to know what makes these powerful lightning bolts more likely to form in some places than in others,” Ephraim said.
The new study provides the first explanation for the formation and distribution of superbolts over land and sea around the world.
Storm clouds often reach 12 to 18 kilometers (7.5 to 11 miles) in height, covering a wide range of temperatures. But for lightning to form, the cloud must extend over the line where the air temperature reaches 0°C (32°F).
Above the freezing line, in the upper reaches of the cloud, electrification occurs and generates the "charge zone" of lightning.
Ephraim wondered whether changes in the elevation of the freezing line, and thus the elevation of the charging zone, could affect a storm's ability to create superbolters.
Previous studies have explored whether the strength of extreme lightning strikes could be affected by sea spray, shipping lane emissions, ocean salinity, or even desert dust, but those studies were limited to regional bodies of water and can explain at most only part of the regional distribution of lightning strikes. Super. A global explanation for super lightning hotspots has remained elusive.
To determine why superbolters cluster over certain areas, Ephraim and his colleagues needed to know the time, location and energy of specific lightning strikes, which they obtained from an array of radio wave detectors.
They used this lightning data to extract key properties from storm environments, including land and water surface height, charge zone height, cloud top and base temperatures, and aerosol concentrations. They then looked for correlations between each of these factors and the superpower of a lightning bolt, and came up with insights into what produces powerful lightning.
The scientists found that, contrary to previous studies, aerosols did not have a significant effect on the superpower of the lightning bolt. Instead, the smaller distance between the charging area and the ground or water surface resulted in significantly increased lightning activity.
Storms near the surface allow higher energy spikes to form, because a shorter distance generally means less electrical resistance and therefore higher current. A higher current means stronger lightning strikes.
The three regions with the highest number of superlightenings — the northeastern Atlantic, the Mediterranean, and the Altiplano Mountains — all have one thing in common: short gaps between lightning charge zones and surfaces.
“The correlation we saw was very clear and significant, and it was very exciting to see it happen in all three regions,” Ephraim said. “This is a huge achievement for us.”
Ephraim noted that knowing that the short distance between the surface and the cloud charging zone leads to more superlightening will help scientists determine how changes in climate will affect the occurrence of superlightning in the future. He added that warmer temperatures could cause an increase in weaker lightning, but increased humidity in the atmosphere could counteract that. There is no definite answer yet.
The team plans to explore other factors that could contribute to the formation of a superbolt, such as the magnetic field or changes in the solar cycle.
The study was published in the journal Geophysical Research: Atmospheres.
Life-sized camel sculptures discovered in the Saudi desert
Scientists have discovered life-sized paintings of camels on a rock near the southern edge of the Nafud Desert in Saudi Arabia.
In a new study, scientists from the Max Planck Institute for Geosciences in Germany documented a group of sculptures.
This huge work of art depicts dozens of life-sized wild camels, but what is most surprising is that the paintings depict an extinct species that roamed this region of the desert in the Arabian Peninsula for thousands of years, but which never received a scientific name, according to a study published in the December issue. From the journal Archaeological Research in Asia.
This site, called Sahut, has been studied by other archaeologists for years, but this is the first time that archaeologists have noticed camel carvings on the outcrop.
“We knew about the site from another research paper, but it was difficult to find the paintings because their location was not precise,” Maria Guagnin, lead author of the study and a postdoctoral researcher at the Max Planck Institute for Geological Geoscience in Germany, told Live Science. .
The search for the sculptures was complicated by the fact that their exact location alongside the sand dunes was not determined, in addition to the fact that the sculptures contained newer inscriptions intertwined with the camels.
The team points out that this also makes it difficult to understand what culture created this artwork and when.
“The carvings contain a dense collection of rock art from many different periods,” Guagnin added. “You can see that the carvings were made in different stages and are different in style.”
The study also indicates that most of the carvings were made inside cracks, making them difficult to access and radiocarbon date.
However, radiocarbon dating of two nearby ditches and hearths indicates that the Sahut site was occupied between the Pleistocene, also referred to as the Pleistocene or Pliocene (2.6 million to 11,700 years ago) and the Middle Holocene (7,000 to 5,000 years ago). According to the study.
The natural pattern of carvings depicting animal fur and sex also provides clues about when they were created.
The study's authors believe that the carvings were painted on the rocks during the camel's mating season. This is evident through images of male animals flaunting their uvula, an organ that hangs from their mouths and is used to attract females. (The mating season for camels usually occurs between November and March.)
More research is needed to understand the importance of this site. “There is no known source of water, so perhaps there was something else that brought people here,” Guagnin said. “Maybe it was a good stopping point on their way to another site. It must have been an important site, but at the moment, we are not sure why.”
Sahut is not the only site in Saudi Arabia where camel sculptures have been found. In 2018, archaeologists discovered a 2,000-year-old “parade” of life-sized camels in Al-Jawf Governorate in the desert of northwestern Saudi Arabia.
Wow! Amazing!
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