Scientists uncover surprise origin of wispy cirrus clouds | Environment

Cirrus clouds are our highest clouds; their delicate wispy strands are like an artist’s brushstrokes in the sky. During the day they are bright white and at dawn and dusk they can take on the hues of sunrise and sunset. But how are they made? New research reveals that some cirrus clouds are seeded by storms halfway around the world, several thousand miles away. This has implications for global warming as storm patterns change.

Meteorologists have long recognized two types of cirrus clouds: “anvil” cirrus clouds, which spread from large storm systems, and “in situ” cirrus clouds, which appear to form on their own. Distinguishing them is tricky, but by applying a new computer analysis to satellite cloud data, researchers found that in situ cirrus clouds emerge in response to major storm systems on the other side of Earth.

In a paper published in the journal American Geophysical Union Advances, they propose that the storms generate massive atmospheric waves that cross the equator, changing the temperature profile in the upper atmosphere and causing the emergence of cirrus clouds in situ. Cirrus clouds are thought to let sunlight through and trap heat in the atmosphere, resulting in a net warming effect. So we now need to understand whether future changes in storm patterns will alter the distribution and quantity of cirrus clouds.