Severe flooding, storms and mudslides have pummeled the state of California,
resulting in deaths, enormous property damage and leaving a path of destruction in its wake.
The cause?
Atmospheric rivers which are storms akin to rivers in the sky that dump massive amounts of rain.
(Gavin Newsom, California Governor)
"The reality is this is just the eighth of what we anticipate will be nine atmospheric rivers."
Nine consecutive rainstorms inundated California in succession starting from December 26, finally fading after three weeks.
(Seth Shaprio, Santa Cruz resident)
"It was just this huge wind gust, just swept over our area and trees blowing and a lot of rain just came in very quickly."
Let's take a closer look at this weather phenomenon.
How common are atmospheric rivers?
These "rivers in the sky" are relatively common, with about 11 present on Earth at any time. That's according to NASA.
Most atmospheric rivers are weak and do not cause damage. In fact, they can provide much needed rain or snow.
How big are they?
Atmospheric rivers can carry up to 15 times the volume of the Mississippi River. That's according to the National Oceanic and Atmospheric Administration.
They appear as a trail of wispy clouds that can stretch for hundreds of miles.
Can they be dangerous?
In 2019, an atmospheric river nicknamed the "Pineapple Express" hit California.
The water vapor brought rain and triggered mudslides that forced motorists to swim for their lives.
Two years later in 2021, an atmospheric river dumped a month's worth of rain on British Columbia in two days,
prompting fatal floods and landslides and severing access to Canada's largest port.
What impact will climate change have on them?
Scientists say atmospheric rivers of the kind that drenched California will become larger -- and possibly more destructive -- because of climate change.
Columns in the atmosphere that are hundreds of miles long carry water vapor over oceans from the tropics to more temperate regions
in amounts more than double the flow of the Amazon River.
That's according to the American Meteorological Society.
Its research paper from 2018 says there are projected to be 10% fewer atmospheric rivers in the future.
But they are expected to be 25% wider and longer, and carry more water.
