science of meteorology

temperature from average, and symbols of the weather. From these charts he deduced general rules, based on actual observations, on the relationship between the surface pressure and wind fields, the temperature distribution around a depression, and the pattern of rainfall.

Buchan was able to trace the movement and development of depressions over time, though this was difficult with only one chart per day. The winds around a depression in the northern hemisphere blew in an anticlockwise direction around the centre of low pressure, but with a component towards the centre. Since this did not lead to a rapid rise of pressure he concluded that the air must be rising within the depression and flowing away from it at a higher level. These analyses confirmed the earlier conclusions of Espy and Loomis in the USA, who had carried out similar synoptic studies there, and they contradicted Dove’s ‘Theory of Storms’, which had previously held sway.

Buchan followed this with a paper in the JSMS published in 1868, entitled On two storms which passed over the United States between the 13th and 22nd March 1859; with remarks on storms which occurred at the same time in N Atlantic, Europe and W Asia. In this, as well as land observations, he used logs from 53 ships at sea over the North Atlantic. Six storms were identified and their movement traced in the period 13th–29th March 1859. The paper states that 21 working charts were constructed, of which three were published; these show the tracks of the storms, one of which, having crossed America, divided, with one part dying out near the Azores while the other part went ENE across the Atlantic and gave a particularly severe storm over Northern Scotland. In the second edition (1868) of his Handy Book of Meteorology, described as the first textbook of modern meteorology, Buchan championed the use of charts of surface pressure to study individual storms and to chart the mean distribution of pressure. Included were the first global charts of mean surface pressure. Then, as more data became available, in 1869 he published in the Proceedings and the Transactions of the Royal Society of Edinburgh maps of annual and monthly mean pressure and prevailing winds over the globe. He showed that the same relations occurred between the mean pressure field and the prevailing winds as for individual storms. The maps were refined and updated, using longer periods of observation, during the years following the Challenger Expedition of 1872–76, and Buchan compiled the Challenger report on atmospheric circulation (1889). These charts were included among 400 maps in volume 3 of Bartholomew’s Physical Atlas (1899), prepared by A J Herbertson and edited by Buchan.

In 1883 the SMS set up a manned weather observatory on the summit of Ben Nevis, and this provided hourly observations until it closed for financial reasons in October 1904. The observations were published in full in four volumes of the Transactions of the Royal Society of Edinburgh. In 2017, digital data sets of the observations were created in a citizen science project and these provide a most valuable record of mountain weather in the UK. At the observatory, experiments relating to cloud condensation were carried out using the dust counter of John Aitken of Falkirk, who was a pioneer in cloud physics research.

With the amalgamation of the SMS with RMetS in January 1921, Scotland lost a natural forum for meetings to discuss meteorological developments, but in 1944 James Paton became the first lecturer in Meteorology within the physics department of Edinburgh University, and in June 1946 the RMetS set up a Scottish Centre; James Paton became its Meetings Secretary. The Scottish Centre has continued to the present day with regular meetings, usually in Edinburgh, and there is also now a sub centre at Inverness. In 2008, RMetS and RSGS jointly funded a memorial seat for Alexander Buchan to be placed in Kinnesswood, where he was born.