Fair weather often seems to play hard-to-get on warm season weekends. During the work week, we toil under buzzing fluorescent tubes, teased by the orgy of photons just beyond the windows. But when the weekend arrives, too often it seems to bring gray, drizzly skies with it, ruining countless outdoor plans.

Well, this phenomenon is not merely the product of pessimistic imaginations, it seems. A study conducted at by Arizona State University researchers found that it is 22% more likely to rain on a weekend than a weekday, based on over 50 years of weather data from the Eastern Seaboard. To make matters worse, the researchers hypothesize that this rain is OUR fault, because it is likely due to the emissions from our internal-combustion vehicles. Automotive pollution from millions of commuters generates tons of tiny airborne particles called aerosols, and these gather in the sky to become nucleation sites, where water vapor condenses into raindrops. Stupid climate karma.

Owing to a similar mechanism, a study in 2017 showed that lightning strikes are approximately twice as common over oceangoing shipping routes compared to the general atmosphere. This is owing to the aerosols emitted by container ships, which can freeze high in the atmosphere and jostle against one another to build up electric charge. This effect is known as “aerosol convective invigoration.”