Code No: 695
Video Running Time:
METEOROLOGY FOR SAFE NAVIGATION IN TROPICAL AND EXTRATOPICAL
CYCLONES
Routine passages for many ships include areas where high winds and
rough seas can occur due to the proximity of cyclones.
Taking the example of the sea areas around Japan and the North
Pacific, the video first explains how air masses influence and
cause the generation of cyclones. It is the mixing of two air
masses that can give rise to the formation of cyclones.
Extratropical cyclones can be classified in two types according to
the prevailing atmospheric pressure and wind speed. Cyclones can be
forecast from data contained in surface and upper atmosphere
weather charts.
The video shows how depressions can develop into cyclones, also
where they tend to start and how they subsequently behave. The
paths taken by cyclones are influenced by time of the year. The
theory is illustrated by looking in detail at the behaviour and
movement of actual recorded cyclones. This explains how
exceptionally high waves become associated with cyclones; these
high waves cause casualties at sea.
Ships should avoid areas of high waves by using weather routing.
Weather routing is a computer simulation that takes account of
ship's speed and the ocean environment. It provides a
recommended route to avoid areas of high waves. The video shows how
ship speed in waves is obtained so making it possible to find the
optimum route for the shortest voyage time. The technique is called
the ‘isochrone method’.
The video further explains how to use observations of wind speed
and direction onboard to stay safe in the vicinity of a cyclone.
Generally the SE quadrant should be avoided as high wind and waves
occurs here.
Seafarers need to know how to use available meteorological
knowledge and available forecast data to ensure safe and cost
effective ship operation.
Produced in Association with:
JAPAN CAPTAINS ASSOCIATIONS
