Online WWW Site Link Warning Icon Explanation What's that lighting bolt thingy for? Note: the lightning bolt icon that you see to the left appears before each link that takes you to an online WWW site that is not part of this CD-ROM. A working network connection is required to access this link. Terms for using data resources. Credits and Acknowledgments for WW2010. Department of Atmospheric Sciences (DAS) at the University of Illinois at Urbana-Champaign.