Monsoon

Term derived from the Arabic mawsim, meaning 'season'. In Arabic, mawsim refers to the period of time in which ships could safely depart from port. Collectively, these times were called mawasim al-asfar, 'sailing seasons'. In eastern Asia, the Indian subcontinent, and the Indian Ocean region, the term 'monsoon' refers to two (2) regular periods of northeast and southwest winds.

Of the two monsoons, the southwest was the more dangerous for mariners and inhabitants of western India. In June and July, heavy swells and torrential rains closed ports from Bombay to Cochin (Malabar Coast). The northeast monsoon, on the other hand, beginning in August in western India, meant clear sailing - with steady winds, few squalls, with little or no rain. However, in the Bay of Bengal and the eastern seaboard of India (the Coromandel Coast and Ceylon/Sri Lanka) it made sailing conditions treacherous and dangerous. From Madras to the Hooghly delta (Calcutta), maritime travel became extremely difficult, and even safe ports such as Trincomalee (in Ceylon) could offer little protection from the prevailing weather conditions.

The seasonal warming and cooling of very large continental air masses generate monsoon systems. They depend upon the fact that temperatures over land change more quickly than temperatures over oceans. The Southwest Monsoon results from warming air over southern Asia rising and drawing in toward the land the relatively cooler and more humid ocean air. As the ocean air warms and rises in turn, the moisture condenses, and produces torrential monsoonal rains. Later in the year the system reverses as relatively warmer ocean air rises, drawing after it the relatively cooler dry air above the land. This creates the northeast winds (Northeast Monsoon) which, on the west coast of India, results in cool, sunny and dry weather, quite favourable to maritime trade and activity. There are separate monsoon systems that affect parts of North America, Central America and northern Australia at other times of the year.

This meteorological dynamic is reflected in a number of ways in Lachlan Macquarie's journals and letters. His references to the 'monsoon' describe daily events in Bombay, Calicut, Tellicherry, as well as the arrival and departure of convoys of East Indiamen vessels at certain points of time: 'the ships of the season.' The monsoon season placed quite precise restraints and constraints upon the movement of people, the receipt and dispatch of goods within the Asian region, and most particularly upon voyages to and from Britain. Lastly, the planning and implementation of military campaigns was predicated upon the timing of the monsoon. This is clearly evident in the campaigns against Tipu Sultan in Mysore in 1791-1792 and 1799. The early arrival of the monsoon in May 1791 created a strategic disaster for the British forces retreating from Seringapatam. Macquarie's description highlights the difficulties and dangers of travelling through the jungle terrain of the Western Ghats during the monsoon season.

Lastly, the monsoon was regarded as something of a mortality indicator. The phrase 'two monsoons' was a vernacular expression highlighting the real health dangers posed for Europeans living in the subcontinent - they often died within two monsoons of their arrival.

Sources:
Saudi Aramco World Vol. 56, No. 4 July/August 2005 p.7; Wilkinson, Theon, Two Monsoons. London: Duckworth, 1976 pp.1-17.

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