A powerful atmospheric river pounded Washington State in the Pacific
Northwest this week, killing at least two people and
knocking out power to hundreds of thousands with temperatures around
the world rising. Scientists say these weather systems will
become larger and possibly more destructive. So what is
an atmospheric river? Alison Santarelli, a meteorologist for
the National Oceanic and Atmospheric administration breaks it down.
Atmospheric river is a pretty much you can think of
it as like a river in the sky. So
a river transports, as we know, a river
transports a lot of water. And so atmospheric river
are essentially that just up in the sky, they're
relatively long narrow regions with significant water vapor that helps
to transport moisture from the tropical areas into the mid
latitude which is where the United States is located.
Atmospheric rivers appear as a trail of wispy clouds that
can stretch for hundreds of miles as the water vapor
in the jet stream rises, it cools and condenses
resulting in rain or snow. According to Noaa,
an atmospheric river can carry 15 times the volume of
the Mississippi River. Most atmospheric rivers are weak and
do not cause damage. In fact, they can
provide much needed rain or snow. A 2018 research
paper projected there to actually be 10% fewer atmospheric rivers
in the future. But that's not necessarily a good
thing. If moderate atmospheric rivers occur less frequently,
it could make managing water supplies more difficult and more
bad news. The same study found that atmospheric rivers
in coming years are expected to be 25% wider and
longer and carry more water potentially wreaking more havoc in
vulnerable mid latitude regions. Santarelli explains the part that
rising global temperatures play in the equation. So scientific
research has shown that the climate is warming and a
monthly to yearly temperatures are increasing now, while it's
difficult to say exactly how this might impact atmospheric rivers
specifically. Certainly we do know that warmer air is
capable of holding more water vapor. And so it's
possible that a warming climate could result in stronger and
more extreme weather.