Numerous clouds streets often appear in the lee of island arcs during cold-air outbreak. These clouds are quite similar each other in shape and appearance. We found that two different kinds of cloud streets are coexistent in them, one is formed by a mountain and another is formed by the temperature contrast between islands and the sea. Since difference in the characteristics between them is small, it is difficult to simply discriminate by satellite images. However, two kinds of the cloud streets can be observationally classified by the statistics of the satellite images with the help of numerical experiments.