Buchan spells Several periods of the year, ‘more or less well defined’, when the normal seasonal rise or fall of temperature is halted or reversed for a time, e.g. 9–14 May is a cold period and 3–14 December a warm period. They are named after the Scottish meteorologist Alexander Buchan (1829–1907), whose analysis of temperature records for Scottish stations in the middle of the nineteenth century revealed them. Six cold and three warm periods of this type were identified by Buchan in 1869 from his examination of records covering several years. See also SINGULARITY.

Buchan spells Several periods of the year, ‘more or less well defined’, when the normal seasonal rise or fall of temperature is halted or reversed for a time (e.g. May9–14 is a cold period and December3–14 a warm period). They are named after the Scottish meteorologist Alexander Buchan (1829–1907), whose analysis of temperature records for Scottish stations in the middle of the nineteenth century revealed them. Six cold and three warm periods of this type were identified by Buchan in 1869 from his examination of records covering several years. See also singularity.