May 15, 2022 5:04 pm

Cloud Streets on the Great Lakes

Francis Martin Leon 3 min
MODIS image on NASA’s Terra satellite over the Great Lakes from January 10, 2022.

The middle of winter in North America often brings gusts of cold wind blowing south from the Arctic or interior Canada. In addition to causing snow and freezing the Great Lakes, winds can create features that look like long white highways in the sky.

Cloud streets are parallel bands of cumulus clouds that form when frigid air near the surface blows over warmer waters, while a layer of warmer air (a temperature inversion) rests on top of both. The comparatively warm water gives up heat and moisture to the cold air, leading to columns of hot (thermal) air rising through the atmosphere.

Hot air in temperature inversion acts as a lid, so that rising, humid thermals hit the air mass above and roll on themselves. This creates horizontal parallel rotating air cylinders. On the upper side of the cylinders (rising air), the moisture cools and condenses into flat-bottomed, spongy-topped cumulus clouds that align parallel to the wind direction. Along the descending side (falling air), skies remain clear to form a cloudy-clear-cloudy striped pattern.

Formation of the cylinders explained in the text. ZAMG

The MODIS sensor on NASA’s Terra satellite featured such an event over the Great Lakes on January 10, 2022. The image is a combination of natural color, shortwave infrared, and near infrared, a combination that helps distinguish snow and ice (blue/cyan) from clouds (white). Cloud streets that day stretched for hundreds of miles, mostly rising from Lake Superior and Lake Michigan.

Detail of the image above.

Cloudy fairways are more common over the Great Lakes in the early part of winter, as the fresh water is still cooling from the summer and winter ice is beginning to form. The cloud phenomenon also occasionally coincides with lake-effect snow downwind.

Picture of NASA Earth Observatory by Joshua Stevens, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Michael Carlowicz and Adam Voiland.

NASA Earth Observatory

Comments (0)

Leave a Reply

Your email address will not be published.