Jet Streak Creates Huge 'Impressive' Cloud Arc Over North America, NASA Image Shows

A huge arc of cirrus cloud appeared over the northern U.S. as a result of a "jet streak" in the upper atmosphere. An image from NASA shows the cloud stretching from the west of Nebraska, over Minnesota and part of Canada, all the way to northern Michigan.

A jet stream is a band of strong, fast-moving air that circles the globe in the upper levels of the atmosphere. It is caused by differences in temperatures from Earth being heated unevenly, explained Emily Berndt, a research scientist at the Marshall Space Flight Center.

"The uneven heating from the tropics to the poles causes differences in pressure, which drive the wind," she told Newsweek.

"Jet streaks are regions of faster flowing air within the jet stream. They are more common and more intense during the winter months due to the greater temperature contrast between the mid-latitudes and polar regions. On any given day there can be several strong jet streaks embedded in the jet stream globally."

While jet streaks are not especially rare, they are hard to detect on normal satellite images. In the image taken on November 28, the presence of a huge arc of cirrus clouds associated with the jet streak can be seen. Jet streaks are involved in the formation of winter storms as the rising air can trigger cloud and rain, NASA Earth Observatory said in a statement.

jet streak
Jet streak led to a huge arc of cirrus clouds appearing over North America. The NASA image was taken on November 28. NASA Earth Observatory

The image of cirrus clouds above North America was taken with the space agency's Terra Satellite. At the time, a strong winter storm was building to the east, NASA noted. This storm eventually produced over a foot of snow in some parts of the Midwest and New England.

Berndt said jet streaks are important to the formation of mid-latitude cyclones and the severe weather and/or storms they produce. While the air in jet streams and streaks flows horizontally, there is vertical motion at the entrance and exit. "The horizontally flowing air speeds up as it enters the jet streak or slows down as it exits the jet streak. This creates imbalance and some of the air needs to rise/sink to restore balance," she said.

Paul Gunderson, from the U.K.'s Met Office, told Newsweek that the arc of clouds seen is associated with air ascending. "Warm air rises in the right entrance region of the jet, cold air sinks near the left entrance region. As the warm air rises, it condenses, thus leaving a cloud signature," he said.

With this arc of clouds, there was vertical motion at the entrance to the jet streak. The clouds were pulled north and east as the jet streak moved the clouds along.

"There was just enough vertical motion and moisture to create clouds that were then caught in the jet stream flow to create an arc," Berndt said. "It is common to have cirrus clouds form on the poleward side of the jet stream. This particular arc was impressive because it was so distinct from the lower clouds and snow on the ground in the image and formed a smooth semi-circle as it followed the jet stream pattern. "