- The idea that it rains more on weekends because of weekday pollution is a myth.
- But it is true that pollution can have a small effect on rainfall in highly polluted or dense areas.
- That effect wouldn’t make a big enough difference for you to notice it, however, and most scientists don’t think the “weekend effect” is real.
- Generally speaking, it is more common for rain to fall in the afternoon.
If it feels like you’re getting drenched every weekend, rest assured: the sky is not out to get you this summer.
Ever since the industrial revolution in England, scientists have worried that we might be ruining our own weekends by creating weekday pollution that leads to more rain on Saturdays and Sundays.
The idea is that as people pollute the air with exhaust from cars and factories, we send more solid, rain-fuelling particles called aerosols into the atmosphere. Those tiny pieces of industrial trash become building blocks for clouds, since water can condense onto them. But when lots of aerosols are floating around in the atmosphere, they can crowd each other out and create much smaller cloud droplets, leading to less rainfall.
“They take longer to grow big enough to fall out as rain,” Angeline Pendergrass, a project scientist at the University Corporation for Atmospheric Research who studies precipitation, told Business Insider.
But she said any argument that this phenomenon makes weekend days rainier simply doesn’t hold water. “If there is an effect, it’s really small,” she said.
Some of the most recent research-based myth-busting on this subject was done by weather expert David Schultz in 2007. After studying more than 200 weather stations across the US, Schultz and his colleagues ruled that there was no discernible pattern of particularly rainy days in a week.
The processes through which aerosols form clouds are complex, and pollution is not the only thing determines when rain falls or how long clouds stay in the air. Aerosols can also build up from all sorts of natural solids like dirt and salt. Weather patterns also change based on other factors like the jet stream and whether clouds form over land or sea.
The real reasons for your rainy weekends
Pendergrassproposes a different reason why it can feel as though it’s raining more on the weekends.
“I think it’s more psychological than meteorological,” she said.
When we’re out of the office and want to be spending our days at the beach or in the park, it can be very disappointing to see rain in the forecast. Those strong feelings can make weekend precipitation more memorable, even though there’s no true increase on Saturday or Sunday.
There may also be an additional reason why weekends seem extra-rainy this year in particular: portions of the US are much rainier than normal right now.
It’s been a wet spring across several areas of the country, especially on the East Coast and throughout the northern plains. Rainfall in areas around Washington DC has been 300% above usual in the last 30 days. Parts of Florida, Nebraska, and Montana have been equally soaked.
Scientists like Pendergrass who study the global climate say people should get used to this: increased rainfall is part of a warming world. So are stronger, more damaging hurricanes. Think of it like the Earth’s version of a feverish sweat.
But if you want to know the best time of day to make plans based on the chances of rain, here’s an evidence-based hack: stay inside in the afternoon.
When the sun comes up in the morning and starts heating the surface of the Earth, warm air rises and clouds form. By afternoon, there’s enough energy in the sky for a storm to form. So if it’s pouring on you on a weekend afternoon, you can blame that hot ball in the sky, no matter what day it is.
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