In spring, it's not uncommon for a cloak of thick fog to cover the Yellow Sea. The shallow sea, which has a number of busy ports, usually sees 50 foggy days a year, but some weather stations in the area have measured as many as 80 days. One of those days was March 28, 2012, when the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA's Aqua satellite captured this natural-color image of a fog bank hugging the Korean coast.