Visualized on Google Maps is wind data from the numerical weather prediction model GPV (meso scale model) by Japan Meteorological Agency at the surface level (10 meter height). You can see the wind data all over eastern Japan centered on Fukushima Daiichi nuclear power plant of Tokyo Electric Power Company (TEPCO). Moving the slider shows you the past and the future of wind direction and speed. Winds in the upper atmosphere is available at World-wide Real-time Wind Maps.
For your information, the marker version was integrated into a more advanced World-wide Real-time Wind Maps. Weather information around nuclear plants is also available at SPEEDI radiation monitoring and weather information around nuclear facilities (in Japanese), such as Fukushima Daiichi Nuclear Power Plant. In the same way, Active volcanoes in Japan (in Japanese) shows wind direction and speed around Japanese volcanoes.