This colour image of an ethylene-air diffusion flame as recorded 1.3s after ignition in the NASA Glenn Research Center 2.2-Second Drop Tower. The flame sheet and soot are clearly visible. Ignition was performed in microgravity, and more ignition nonuniformities had dissipated here. The camera used is a Nikon D100 digital still camera with a resolution of 6 megapixels. The scale is indicated by the 6- mm spherical burner.