Monsoon trough of the summertime Asian monsoon is in its normal orientation (oriented east-southeast to west-northwest), tropical cyclones along its periphery will move with a westward motion. If it reverses its orientation, orienting southwest to northeast, tropical cyclones will move more poleward. Tropical cyclone tracks with S-shapes tend to be associated with reverse-oriented monsoon troughs. The South Pacific convergence zone and South American convergence zones are generally reverse oriented. The failure of the monsoon trough, or the ITCZ, to move south of the equator in the eastern Pacific Ocean and Atlantic Ocean during the southern hemisphere summer, is considered one of the
Rockall Natural Resources, to conduct a seismic survey of the Rockall Bank and the Hatton Bank in July 2004, as part of the Irish National Seabed Survey. The island's only permanent macro-organism inhabitants are common periwinkles and other marine molluscs. Small numbers of seabirds, mainly fulmars, northern gannets, black-legged kittiwakes, and common guillemots, use the rock for resting in summer, and gannets and guillemots occasionally breed successfully if the summer is calm with no storm waves washing over the rock. In total there have been just over twenty species of seabird and six other animal species observed (including the aforementioned molluscs)