The Fukushima accident's radioactive plume. The map displays areas which have been overflown by the plume.
Made by the Graphic Lab/Map workshop's wikigraphists (WP:GL/MAP)
Sources 2011/03/18:

ZAMG's website ZAMG = Central Institute for Meteorology and Geodynamics, Austria
Formerly: Nouvelle simulation du nuage de pollution radioactive au Japon (2011-03-16). Archived from the original on 2014-02-13. Retrieved on 2011-03-18.Note: Aeronobie.be now ask to cite and follow the Zamg.ac.at's page (currently the main source), stating: '--Varlaam  21:19, 24 March 2011 (UTC)'"The World Meteorological Organisation asked the Central Institute for Meteorology and Geodynamics (or ZAMG, Austria) to support the International Atomic Energy Agency by providing the atmospheric plume calculations."
Background based on:

A blank map of the world centred at the 180E longitude line.  Detailed SVG map with grouping enabled to connect all non-contiguous parts of a country's territory for easy colouring.  Smaller countries can also be represented by larger circles to show their data easier.  A thorough description of use and other instructions relating to can be found on the instruction page
Own work based on: BlankMap-World-180E.svg
BlankMap-World-180E.svg: Lokal_Profil / derivative work: Yug