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 flora and fauna. They chartered the "Granuaile". A detailed underwater mapping of the area around Rockall undertaken in 2011–2012 by Marine Scotland showed that Rockall itself is a minor pinnacle, whilst Helen's Reef extends in a sweeping arc of fissures and ridges to the north-west of the islet. Between the islet and Helen's Reef is a deeper trench much used by squid fishermen. The area where Rockall is in, is located in the pathway of the warming and moderating Gulf Stream. Although the rock does not sustain any weather station, the isolated nature of the setting dictates an extremely maritime