A satellite imagery video of the atmospheric river hitting the west coast of the United States
Atmospheric rivers are storms akin to rivers in the sky that dump massive amounts of rain and can cause flooding, trigger mudslides and result in loss of life as well as enormous property damage.
California has been battered by a series of such storms since Christmas.
Atmospheric rivers can carry up to 15 times the volume of the Mississippi River, according to the National Oceanic and Atmospheric Administration. They appear as a trail of wispy clouds that can stretch up to hundreds of miles (km).
Research predicts that climate change will cause atmospheric rivers to become 25% longer and 25% wider and to carry more water. This could make managing water supply much harder as moderate atmospheric rivers, which can be beneficial for water supplies, will be less frequent, and strong ones could become more calamitous.
Bomb cyclones are often associated with atmospheric rivers and typically form in winter when cold and warm air masses collide. Also called "explosive cyclogenesis” or a “weather bomb", a bomb cyclone is a low-pressure system that experiences a fall in pressure of 24 millibars in 24 hours.
Carl Schreck, a weather scientist at North Carolina State University, has said atmospheric rivers can supercharge a cyclone’s engine.
Scientists say warmer air and water temperatures from climate change can lead to more evaporation for storms to absorb and dump.
Massive storms are increasingly deluging California followed by periods of drought that increase the risk of wildfires. The storms’ howling winds uproot trees already weakened by prolonged drought and poorly anchored in rain-soaked soil, taking down power lines with them and blocking roadways across the region.
Amid the cycles of wet and dry — both phenomena exacerbated by climate change — the state is experimenting with capturing the megastorm floods to ease destructive droughts.
NOAA, CIRA, NAIP Imagery
Josie Kao, Sandra Maler and Julia Wolfe