This applet uses a particle system to visualize wind patterns in the San Francisco Bay Area, using observed wind data and a computed vector field based on these data.

The applet here is based on data from July 1999, but you can find a current animation at http://sfports.wr.usgs.gov/wind/streaklines.shtml. When that site is down you might also try the page at www.met.sjsu.edu/wind.

The source code for the applet is available under the terms of the GPL.

You can pause and restart the animation with a mouse click.