Global cloud imagery are compiled by the University of Wisconsin-Madison (UW) Space Science and Engineering Center (SSEC) and accessed via their RealEarth™ Web Map Service (WMS). These hourly imagery are composites of approximately 14 satellites, both geostationary (GEO) and low earth-orbiting (LEO). Infrared imagery are provided at approximately 4-km (2.5-mile) resolution while visible imagery have a higher 1-km (0.6-mile) resolution. Visible imagery can only see clouds when it is daytime while infrared can sense clouds during the day and nigh.