Tropical cyclones mostly develop over the ocean between the latitudes of 5 degrees and 20 degrees, where convection is very active.Some isolated cumulonimbi are organized into cloud clusters with diameters of several tens to a few hundreds of kilometers;
some of the cloud clusters further grow into tropical cyclones.
The image shows the Typhoon No.10 (ETAU) over Okinawa. This typhoon traveled over Japan Islands from south to north and seriously damaged all over Japan.