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
Gale force for coastal areas, between and . The definition is very non-standard. A common alternative definition of the maximum is . The most common way of measuring wind force is with the Beaufort scale which defines a gale as wind from to . It is an empirical measure for describing wind speed based mainly on observed sea conditions. On the original 1810 Beaufort wind force scale, there were four different "gale" designations whereas generally today there are two gale forces, 8 and 9, and a near gale 7: The word "gale" is derived from the older "gail", but its origin