Saffirâ€“Simpson hurricane wind scale
The Saffir -Simpson Hurricane Scale ( SSHS short ) was founded in early 1970s by Herbert Saffir and Bob Simpson, a former director of the U.S. National Hurricane Center based on studies of the effects of hurricanes, especially Hurricane Camille, developed and 1972 officially introduced by the National Hurricane Center.
The scale used to classify the wind speed of storms. The division into five categories, starting with 1, was made according to the height of the waves generated by the storm and the air pressure in the center ( eye) of the hurricane.
The scale was developed first and primarily for navigation, which is why the exact range limits are defined in knots. The boundary between tropical and tropical storm depth (34 nodes) corresponds to the boundary between wind force 7 and 8 on the Beaufort scale and the boundary between tropical storm and hurricane ( 64 nodes ) corresponds to the boundary between the wind force 11 and 12 on the Beaufort scale. However, the wind speed in the United States traditionally in mph (miles per hour ) is specified.
Version until the end of 2011
The scale had until the end of 2011, the following classification:
Since 2012, the measurements are for the published wind speeds converted as follows:
Because of this dual rounding resulted in the fourth hurricane category the following problem:
So in converting node in miles per hour for 115 kn it comes to a change of category assignment. A similar problem arises from the conversion of 135 knots in km / h:
To solve this problem, lower and upper limit of category 4 for all units ( knots, mph and km / h) were adjusted ( change of 1 kn). In addition, appropriate amendments to the upper limit of category 3 and the lower limit of category 5 were made. Thus emerges the problem no longer on: