If you've always thought people who claimed they could smell when the rain was coming were making it up - unfortunately, it turns out there's some scientific truth to it.
Many people claim they can tell that rain is on the way just by their sense of smell, even if its a bright sunny day outside - and often, their hunch is proven right.
However, the phenomenon of 'smelling rain' can be backed up by science due largely to petrichor.
The word petrichor comes from the Greek word petros - meaning stone - and ichor - the fluid that flowed in the veins of ancient gods.
The term, first coined in 1964 by mineralogists Isabel Joy Bear and Richard Thomas, stands for the scent that is released by the ground after heavy rain, and is particularly noticeable after a long dry spell.
The sensation, which both humans and animals often find pleasant, comes from Streptomyces, a common bacterium found in soil, which produces a compound called geosmin, according to IFLScience, which the human nose is attracted to.
According to the outlet, the human nose is so adept at detecting trace amounts of geosmin that it even outperforms a shark's ability to smell blood in water.
Geosmin is produced by the bacteria in order to attract insects and other vertebrates, which then get covered in the spores and disperse them more widely.
Researchers showed in 2015 that when it rains, water droplet impact with a surface and flatten out, trapping pockets of air in the pores of the ground.
Those pockets then burst out of the water and become tiny aerosols, taking particles of whatever was on the ground with them, incuding geosmin, which is then carried across vast distances in the air.
These particles can be carried miles ahead of the rainclouds themselves, meaning this is what people are smelling when they can sense it is soon about to rain.
Another contributing factor to being able to smell rain is down to ozone in the wind, which has a sweeter scent to it than petrichor, which is found to be more earthy.
Ozone is a naturally occuring gas but can also be produced by man-made fertilizers and other pollutants, as well as from an electrical charge, including a lightning strike or artificial source.
The smell of ozone in the air can also be an indicator that rain is soon to follow as a downdraft from a thunderstorm can send ozone - which is usually found high above us - down to ground level where humans are able to detect it.
So it turns out Karen from Mean Girls may have had an ability to tell when the rain was coming... though it would have been through her nose rather than her cleavage as she claimed.