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 on or near the islet. Cold-water coral biogenic reefs have been identified on the wider Rockall Bank, which are contributing features for the East Rockall Bank and North-West Rockall Bank SACs. In December 2013 surveys by Marine Scotland discovered four new species of animals in the sea around Rockall. These are believed to live in an area where hydrocarbons are released from the sea bed, known as a cold seep. The discovery has raised the issue of restricting some forms of fishery to protect the sea bed. The species are: The earliest recorded date of landing on the island is