Beaufort scale used in Taiwan and mainland China, which are often affected by typhoons. Internationally, WMO Manual on Marine Meteorological Services (2012 edition) defined the Beaufort Scale only up to force 12 and there was no recommendation on the use of the extended scale. Wind speed on the 1946 Beaufort scale is based on the empirical relationship: Where "v" is the equivalent wind speed at 10 metres above the sea surface and "B" is Beaufort scale number. For example, "B" = 9.5 is related to 24.5 m/s which is equal to the lower limit of "10 Beaufort". Using this formula the highest
RRS Discovery over the Christmas period the ship was blocked in by pack ice. A Norwegian whaler was met on December 29, which gifted the "Discovery" a further 50 tons of coal. On December 31 the ship was struck by a violent storm with winds of up to 70 mph (Force 11 on the Beaufort Scale). The ship was driven against the ice, while larger bergs were blown onto the ship by the wind. For eight hours the "Discovery" was repeatedly slammed into and onto thick ice and battered by bergs but MacKenzie was able to slowly work the ship offshore by