In brief: The process that creates lightning has never been precisely understood, but scientists know that ice plays a crucial role. New research into developing cold electrical components may have unexpectedly revealed a significant piece of the puzzle, explaining one of nature's most chaotic phenomenon.
An international group of researchers has discovered new electric properties in ice that emerge when force is applied to bend the material in a certain way. The findings could lead to innovative electrical engineering and help unravel the mystery of thunderstorms.
Lightning and thunderstorms form when powerful updrafts carrying warm water collide with downdrafts carrying ice and hail. As the water freezes and releases heat, it becomes positively charged, while the hail softens and collides with more water, becoming negatively charged.
The separated groups of positive and negative particles generate electrical fields that build until they accumulate enough charge to overpower the Earth's well-insulated atmosphere, releasing lightning. A small portion of the negative particles can also interact with positive particles on the surface, causing lightning to strike the ground.
Scientists have long struggled to understand how the colliding ice and hail within thunderstorms become electrified because ice is not piezoelectric, unlike certain crystals and other solids that can release electric charge when struck. However, in a paper recently published in Nature, researchers from the Barcelona Institute of Nanoscience and Technology and the Universities of Stony Brook and Xi'an Jiaotong demonstrated that ice can exhibit flexoelectric properties when bent.
The discovery could facilitate the production of cheap transducers – components that convert energy – in cold or remote climates. However, the charge density measured in the experiments also closely resembles the charge observed during ice collisions in thunderstorms, suggesting that ice flexoelectricity is a key ingredient in forming lightning.
Experts typically advise people to shelter inside buildings during thunderstorms, as plumbing and wiring can direct lightning away from humans. For the same reason, people should also avoid using electrical switches or water outlets during storms.
Anyone caught outdoors during thunderstorms should seek shelter in a fully closed vehicle and avoid touching components connected to the vehicle's exterior, such as the radio or ignition. Lightning is extremely unpredictable and can strike objects on the ground miles outside of thunderstorms, so people should assume there is a risk if they can hear thunder.