Supersonic, manta rays or slower planes?

White contrails crisscrossing the sky over every major metropolis are a constant visual reminder of the fundamental role of airplanes in modern life.
http://rss.cnn.com/~r/rss/cnn_tech/~3/177726738/index.html (http://rss.cnn.com/~r/rss/cnn_tech/~3/177726738/index.html).