Rainfall in London
Mr. G. V. Vernon has communicated to the Literary and Philosophical Society of Manchester a Paper on the number of Days on which Rain falls annually in London, from observations made during the fifty-six years, 1807-1862. Howard’s Climate of London has been used for the years 1807 to 1831; the Philosophical Transactions for the years 1832 to 1840; and the Greenwich Observations for the years 1841 to 1862. During the entire period of fifty-six years, no month occurred in which rain did not fall.
The minimum number of days occurred in 1832, the cholera year, and 1834; the number of days being 86, 82 respectively. The maximum number occurred in 1848, the number being 223 days.
Taking the quarterly values, we find that rain falls on the greatest number of days in autumn, and the least in spring.
Taking the means of five yearly periods, there appears to be a kind of periodicity in the number of days on which rain falls; having a maximum in 1815 to 1817, and a minimum in 1845 to 1847.