“Rain clouds come floating in, not to muddy my days ahead, but to make me calm, happy and hopeful.” ~ Rajuda.
The pleasant earthy scent that imbues the air when rain falls is called ‘petrichor’ from Greek, petra, meaning stone, and 'ichor', the fluid that flows in the veins of the gods in Greek mythology.
Some scientists believe that people inherited their affection for the scent of rain from ancestors who relied on rainy weather for their survival.
But what makes rain smell so nice?
Some plants secrete oils during dry periods, and when it rains, these oils are released into the air. The second reaction that creates petrichor occurs when chemicals produced by soil-dwelling bacteria known as actinomycetes are released. These aromatic compounds combine to create the pleasant petrichor scent when rain hits the ground.
Another scent associated with rain is ozone. During a thunderstorm, lightning can split oxygen and nitrogen molecules in the atmosphere, and they in turn can recombine into nitric oxide. This substance interacts with other chemicals in the atmosphere to form ozone, which has a sharp smell faintly reminiscent of chlorine.
When someone says they can smell rain coming, it may be that the wind from an approaching storm has carried ozone down from the clouds and into the person's nostrils.
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