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
Ode to the West Wind a prophet who does not only bring "black rain, and fire, and hail" (28), but who "will burst" (28) it. The "locks of the approaching storm" (23) are the messengers of this bursting: the "clouds". Shelley also mentions that when the West Wind blows, it seems to be singing a funeral song about the year coming to an end and that the sky covered with a dome of clouds looks like a "sepulchre", i.e., a burial chamber or grave for the dying year or the year which is coming to an end. Shelley in this canto "expands his vision from