Research by Ariel University and the School of Sustainability at Reichman University has identified trans-gamma-ray emission enhancement (TGE) in two unusual events in January 2018 at the summit of Mount Hermon — without precipitation — demonstrating electron acceleration in clouds and possible impacts on infrastructure and lightning forecasts.
Lightning storms are not only a spectacular natural spectacle but also a complex scientific phenomenon. A new study recently published in the prestigious scientific journal Science of the Total Environment Reveals an extraordinary discovery: Dry lightning storms above the peak of Mount Hermon emitted gamma radiation at particularly surprising intensities, which are evidence of powerful electrical processes occurring in the clouds above our heads.
The research was conducted by student Nadav Meuda and Dr. Yuval Reuveni from the Department of Physics at Ariel University, in collaboration with Prof. Yoav Yair from the School of Sustainability at Reichman University.
Unusual events on the highest mountain in Israel
The study focused on two unusual events in January 2018, in which sharp increases in gamma-ray measurements were recorded, precisely under dry conditions, without significant rain. The measurements were conducted at the Emilio Segre Cosmic Ray Observatory on the summit of Mount Hermon, at an altitude of about 2,000 meters, an ideal area for studying unique atmospheric phenomena.
During the first event, a particularly unusual burst of gamma radiation was recorded, about 3,500 counts per minute, several times the normal level in the area. The second event exhibited lower but still unusual intensities, about 1,600 counts per minute.
The researchers explain that the process that causes the emission of the unusual radiation is the acceleration of electrons to enormous speeds within the clouds, due to the strong electric fields created by lightning storms. These high-energy electrons continue to move within the storm cloud, during which they collide with the nuclei of atoms and molecules in the air; in a braking process (bremsstrahlung), the collision slows them down and releases high-energy gamma photons. These photons reach the ground surface and are revealed as a phenomenon called TGE – Thunderstorm Ground Enhancement. The absence of rain in the events studied was particularly significant, because it allowed the researchers to rule out other effects, such as the washing away of atmospheric radon with rainwater, and to clearly demonstrate that the radiation was generated by the electric fields themselves.
Practical applications of the research
The study also identified an unusual situation in which the increase in gamma radiation occurred while the electric field was actually positive, an extremely rare event. This finding highlights the electrical and structural complexity of storm clouds, and provides further evidence for understanding the physical processes occurring within them.
Besides being of purely scientific interest, the research also provides new tools for improving preparedness for extreme weather events. Powerful gamma-ray emissions can affect sensitive communications and electronics infrastructure, so understanding the phenomenon could help predict such events and protect against them.
According to Dr. Reuveni, "The better we know how to predict such phenomena, the more we can reduce their effects on our lives. Mount Hermon is actually a rare natural laboratory, allowing Israeli scientists to contribute to the global understanding of lightning storms."
Looking to the Future – More Accurate Predictions
The team plans to continue research and monitoring to improve the ability to predict the occurrence of future gamma-ray bursts. The study highlights the need to deploy additional measuring stations to create a network that will provide early warning of such events.
"In the Middle East, there are still very few measuring stations specializing in atmospheric radiation," concludes Dr. Reuveni, "and we hope that the current research will lead to the establishment of additional stations. This way, we can better protect infrastructure and improve our preparedness for unusual atmospheric phenomena in the future."
The research, therefore, not only reveals the scientific secrets hidden behind lightning storms, but also helps us better deal with their possible consequences for our lives here on the ground.
The scientific and applied contribution
- Physics of clouds and lightning – The detection of gamma rays under dry conditions highlights that the electric field alone is sufficient to accelerate particles. The findings also indicate that the cloud structure may change rapidly, from negative to positive charge, creating short-term “windows” of acceleration.
- Space and terrestrial weather forecasting – Gamma-ray bursts indicate a high electrical discharge potential; in the future they may serve as a “warning system” for extreme electrical fields, especially important for aviation sites and sensitive facilities.
- Aviation and satellite safety – Short-range gamma radiation can also reach flight levels (FL300-400). Although the radiation dose is much smaller than from a normal cosmic ray, early detection may help in managing flight paths.
- Environmental quality and climate change – There is growing interest in linking storm electricity to the atmospheric chemical ocean. Gamma radiation indicates areas where strong ionization occurs, affecting aerosol chemistry and the formation of condensation nuclei.
Why Mount Hermon is special – and where to go from here?
In the Middle East, there are almost no high-altitude laboratories for measuring storm radiation. Hermon offers three advantages:
- High altitude – There is less atmospheric space between the observatory and the cloud, so the signal is stronger.
- Semi-arid climate – Many winters are free of prolonged precipitation, which allows the electrical effect to be isolated.
- Proximity to active lightning areas – The connection between the Mediterranean Sea and cold air currents creates heavy storms over Mount Hermon several times a year.
The researchers have already begun deploying additional radiation detectors in lower areas, with the aim of comparing “height versus intensity” and checking whether radiation is also present in the Hula Valley, the Galilee Mountains, and even the Shephelah. In addition, the Ariel University team is promoting collaborations with similar stations in Japan, the US, and the Caucasus, to build Global network That will monitor gamma emissions in real time and provide a universal alert board.
Conclusion and a drop of inspiration
Israeli research on lightning storms on Mount Hermon illustrates how much nature still hides mysteries, and it is often revealed that advanced research tools “in the right place and at the right time” can transform a seemingly routine mountain into a unique laboratory with international contribution.
As Dr. Reuveni concludes: “These storms teach us that critical pieces of information about Earth are hidden in our own backyard. If we continue to measure, compare, and share data, we will discover phenomena that until now were the preserve of space missions.”
In other words, Mount Hermon, a favorite destination for hikers and skiers, is also a unique window into the world of physics at the top of the atmosphere. And perhaps in the near future, the invisible bursts of gamma rays will serve as a stepping stone to improving lightning forecasts, aviation safety, and understanding the electrical processes of our home planet.
