Tropical cyclone scales barometric pressure is low compared with its surroundings. Other classifications historically used include: cyclonic storm where the winds did not exceed force 10 on the Beaufort scale and a Cyclone where the winds are either force 11 and 12 on the Beaufort scale. Between 1924 and 1988, tropical cyclones were classified into four categories: depression, deep depression, cyclonic storms and severe cyclonic storms. However, a change was made during 1988 to introduce the category "severe cyclonic storm with core of hurricane winds" for tropical cyclones, with wind speeds of more than . During 1999 the categories Very Severe Cyclonic Storm
Francis Beaufort tomb may still be seen. His home in London, No. 51 Manchester Street, Westminster, is marked by an historic blue plaque noting his residency and achievements. During these early years of command, Beaufort developed the first versions of his Wind Force Scale and Weather Notation coding, which he was to use in his journals for the remainder of his life. From the circle representing a weather station, a staff (rather like the stem of a note in musical notation) extends, with one or more half or whole barbs. For example, a stave with 3½ barbs represents Beaufort seven on the