Borders of the oceans seas it contains) as follows: Note that these definitions exclude any marginal waterbodies that are separately defined by the IHO (such as the Kara Sea and East Siberian Sea), though these are usually considered to be part of the Arctic Ocean. The CIA defines the limits of the Arctic Ocean differently, as depicted in the map comparing its definition to the IHO's definition. The Atlantic Ocean separates the Americas from Europe and Africa. It may be further subdivided by the equator into northern and southern portions. The 3rd edition, currently in force, of the International Hydrographic Organization's (IHO) "Limits of
Beaufort scale law relating wind velocity to Beaufort force. Wave heights in the scale are for conditions in the open ocean, not along the shore. The wind speeds in different units are not mathematically equivalent; e.g. 12–19 km/h is not equivalent to 8–12 mph, and both are not equivalent to 7–10 knots. The reason is that the Beaufort scale is not an exact nor an objective scale. It was based on visual and subjective observation of a ship and of the sea. The corresponding integral wind speeds were determined later, but the values in different units were never made equivalent. The scale