Yet another way our actions affect the environment.
There is a scientific reason why it always rains on weekends (io9)
If you are in the northeastern United States, and yet another weekend has been ruined by rain, feel free to lean your head out a window and scream at a motorist. They are, for the most part, to blame. In 1998, a group of scientists at Arizona State University analyzed data going back to the 1940s, and found that a disproportionate amount of rain was hitting on weekend days. Since the seven day week isn't natural, they went looking for some unnatural causes of the wet weekends.
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These aerosols act as little seeds to which water droplets can cling. As the amount of aerosols in the atmosphere grows over the week, more liquid water condenses around these little particles. When enough water groups together, it starts to rain. As we drive, or otherwise churn out gas, dust, and liquid, we are seeding the clouds.
But it's not as simple as just cloud seeding. Later studies, which focused on the southern part of the eastern seaboard have found that, when it comes to massive thunderstorms and tornadoes, people need to brace themselves midweek during the summer.