wave in a trade wind belt, moving from east to west, with severe convective activity in rear of its trough.

wave-like disturbance in the monsoon regime of India, moving from east to west, with severe convective activity ahead of its trough.

small scale wave disturbance in the tropics, moving from east to west, with severe convective activity ahead of its trough.

disturbance in the higher levels associated with the equatorial easterly jet, moving from east to west, with severe convective activity in rear of its trough.