Rare Red ELVE Halo Reappears Over Italian Alpine Town

A striking red halo of light appeared over Possagno in northern Italy on November 17, marking the second sighting of this rare atmospheric event in three years. Captured by photographer Valter Binotto, the luminous ring spanned nearly 200 kilometres and formed at an altitude of about 100 kilometres, closely resembling the ELVE he documented in March 2023. The recurrence over the same small town has drawn scientific interest due to the rarity and fleeting nature of such events.

Understanding the ELVE Phenomenon

The halo has been identified as an ELVE — a rapid, expanding ring of light created in the lower ionosphere when a lightning strike releases a powerful electromagnetic pulse. ELVEs last only a millisecond, making them difficult to observe without advanced equipment. In this case, the EMP was generated by a lightning bolt with an exceptionally high current of around 303 kilo-amperes, far stronger than typical storm discharges.

NASA’s Classification of TLEs

ELVEs fall under the broader category of Transient Luminous Events, a group of brief, colourful atmospheric flashes that occur above thunderstorms. These phenomena, first identified by NASA in the 1990s, include sprites, blue jets and other visually striking formations. Their shapes and colours vary depending on atmospheric composition and the nature of the triggering electrical activity.

Colour and Planetary Variations

On Earth, ELVEs appear red because the emitted energy interacts with nitrogen molecules in the upper atmosphere. On planets with different atmospheric compositions, such as Jupiter, their appearance changes. Data from NASA’s Juno mission revealed blue and pink TLEs in Jupiter’s hydrogen-rich upper atmosphere, confirming long-standing theories about their existence beyond Earth.

Exam Oriented Facts

• ELVEs are expanding rings of light formed by electromagnetic pulses from lightning.
• The observed halo over Possagno spanned about 200 km at an altitude of 100 km.
• TLEs were first discovered by NASA in the 1990s.
• ELVEs appear red on Earth due to interaction with atmospheric nitrogen.

A Rare Repeat Over the Alps

Spotting two ELVEs above the same small Alpine town is considered highly unusual, given their millisecond-long lifespan and dependence on specific storm conditions. The event underscores advances in atmospheric observation technology and continues to offer valuable insights into upper-atmospheric electrical phenomena.