A group of parallel cloud lines was identified in seven successive space shuttle photographs taken over the Pakistani offshore zone in the northern Arabian Sea on April 29, 1993. There are a total of 19 lines aligned with the length of the leading line longer than 250 km and an average separation distance (wavelength) of 1 km. We suggest that the lines are generated by an atmospheric solitary wave packet characterized by decreases in amplitudes and wavelengths from the front to the rear. These features are comparable with the dnoidal soliton solution to the Korteweg-de Vries (KdV) equation. The land breeze and katabatic flow are proposed as a possible generation mechanism. ¿ 1998 American Geophysical Union