File:Cloud Streets over Lake Superior (MODIS 2019-01-25).jpg

English: A frozen and frigid scene greeted NASA’s Aqua satellite when it passed over Lake Superior in late January 2019. The Moderate Resolution Imaging Spectroradiometer acquired a true-color image of frozen lakes and a landscape covered extensively in light snow across Ontario, Canada and the states of Minnesota and Wisconsin on January 20. While Lake Superior remained unfrozen, heavy streams of cloud blowing across the blue waters also told a tale of very cold Canadian wind blowing towards the United States. The cloud patterns are known as “cloud streets” and are formed when frigid, dry air blows across warmer, moister water. The dry air picks up water vapor and the warm air rises, causing a cylindrical motion of air. The water vapor freezes into ice crystals as it rises into the frigid air layers, forming clouds at the top of the cylinder, while the warmer air remains cloud-free. This creates long rows of parallel clouds with clear sky in between. The clouds line up with the direction of the wind, in this case, blowing from the northeast towards the southwest.