The characteristic sharp clean odor you smell after a lightning storm is ozone during stormy weather lightning splits oxygen molecules in the atmosphere into free radicals to create ozone

The Fresh Smell After a Lightning Storm: The Scent of Ozone

Have you ever wondered why the air smells so crisp and clean after a thunderstorm? That distinct odor is none other than ozone. Yes, the same ozone that protects us from harmful ultraviolet radiation in the upper atmosphere is responsible for that characteristic sharp aroma after a lightning storm.

When stormy weather strikes and lightning fills the sky, the remarkable phenomenon creates a chemical transformation in the air around us. Lightning has the astonishing power to split oxygen molecules in the atmosphere into separate atoms, known as free radicals. These free radicals then quickly combine with other oxygen molecules to form ozone, a pale blue gas with a uniquely pungent scent.

The process of ozone creation starts with the immense energy of a lightning bolt. As the lightning discharges, it breaks apart the stable oxygen molecules (O₂) into individual oxygen atoms (O). These highly reactive oxygen atoms then combine with other oxygen molecules (O₂) to form ozone (O₃). This ozone is what gives the air that “after-the-storm” fragrance.

The distinct odor of ozone can travel quite a distance depending on wind conditions, allowing us to experience it even if the lightning strikes are far away. Ozone has a sharp smell often compared to chlorine or a bleach-like scent. Some people may find it invigorating, while others might find it overpowering. Nevertheless, it remains a fascinating consequence of nature’s power.

Apart from its olfactory impact, ozone plays a crucial role in the Earth’s atmosphere. In the upper layers, ozone forms a protective layer, known as the ozone layer, which shields us from harmful ultraviolet (UV) radiation coming from the sun. However, near the surface, ozone is considered a pollutant that can irritate the eyes, nose, and throat when present in high concentrations.

While the scent of ozone might be captivating, it’s important to remember that lightning storms can be dangerous. It’s always best to seek shelter indoors and stay away from open spaces during thunderstorms. However, once the storm has passed, you can take a moment to appreciate the fascinating science behind that refreshing, post-storm aroma – the scent of ozone.

Source: New Scientist - What causes the fresh smell before a storm?