On January 6, 2014, the Moderate Resolution Imaging Spectroradiometer MODIS on NASA’s Terra satellite captured this natural-color image (top) of fog forming over the lakes and streaming southeast with the wind. A swirling mass of Arctic air moved south into the continental United States in early January 2014. On January 3, the air mass began breaking off from the polar vortex, a semi-permanent low-pressure system with a center around Canada’s Baffin Island. The frigid air was pushed south into the Great Lakes region by the jet stream, bringing abnormally cold temperatures to many parts of Canada and the central and eastern United States. Read more