James Capper was a distinguished member of the British East India Company’s Madras military service, and he rose to the rank of Colonel and Comptroller General of the Army and Fortification Accounts on the Coromandel Coast. He had a long, active, adventurous and useful life and had the habit of keeping registers of the tides and currents and notable weather phenomena.  In the year 1801, seven years after he had retired from India, Colonel Capper published a book entitled Observations on the Winds and Monsoons of India. This book, which combined theory with fact, both equally valuable, could possibly be regarded as the first formal scientific publication on Indian meteorology. I found some interesting extracts from Colonel Capper’s book in another authentic source, and they are reproduced below: 

“The island of Ceylon, which lies to the southward of Coromandel coast, and where the peninsula becomes extremely narrow, partakes of both monsoons, but principally of the S.W. The wind immediately on the coast, at the commencement of this monsoon, takes nearly the same direction as the coast itself. From the latitude of 9 to 13 degrees, the coast lies nearly N.N.E. and S.S.W., and from the latitude of 15 degrees to the head of the gulf, called Balasore Roads, it runs almost N.E. and S.W. The S.W. monsoon, therefore, on this coast blows at first along shore, from which cause it is called the ‘Long Shore Wind’. The nature of the soil on the coast probably contributes to give it this direction; for the soil being, in some respects, like the Gulf of Guinea on the coast of Africa, low and sandy, the air near the earth must consequently be rarified under almost a vertical sun, and the denser air, coming across the Indian Ocean or the Gulf of Sind, will follow that direction on the coast to fill up the vacuum. But these winds continue only to the end of May or the beginning of June, when the sun being near the summer solstice, the hot land wind on the coast of Coromandel commences, and continues about six weeks. To understand the cause of this sudden change, we must again advert to the geography of the country, and consider the state of the atmosphere at this period on the two coasts”…

“The sun’s declination in the month of May is between 15 and 22 degrees N.; he will therefore before the end of this month have been vertical over all these countries and consequently have produced a considerable degree of heat in the Carnatic; but at the same time the double range of mountains to the westward will have arrested the clouds brought thither by the S.W. monsoon, and made them precipitate their contents both on the Malabar coast and in the Mysore country. The principal point of rarefaction then, at this season, will be the Carnatic, which may, as usual, be considered as the heated room, and the nearest cold body of air will come from the table land of Mysore to restore the equilibrium.”…

“All these circumstances, properly considered, clearly manifest the nature of these winds, or rather positively prove them to be whirlwinds, whose diameter cannot be more than 120 miles, and the vortex seems generally near Madras or Pulicat, where a branch of the Ballagat mountains extends towards the sea.”…

“On the coast of Malabar, however, this monsoon frequently blows with considerable strength at the commencement; but it must be observed that it does not begin at the same time on all parts of the coast, nor does it proceed rapidly in its course towards the N. For, although the change of the monsoon generally takes place at Anjengo about the time the sun becomes vertical at that place, it never reaches Bombay before the middle or rather the end of May; the latitude of the former is about 8º 30’ N., and of the latter 19 degrees.  On the 12 th of April the sun is vertical at Anjengo, and about the 15 th of May at Bombay.  If, then, the difference of latitude and declination be compared, it will be found that the sun and the monsoon move almost precisely together, at the rate of about twenty miles per day – a circumstance, which above all others tends to prove that the sun’s motion in the ecliptic is the primary, if not the sole cause of the motion of the air, or rather the course of the wind, – at least in this part of the world, – I mean on the Malabar coast.”…  

“From these accounts it seems very clear that hurricanes never happen at the breaking up of the monsoon, nor precisely at their commencement, but rather some time after the change, and that they are local and of short duration. But this description of them is not confined to the Malabar coast, nor to that of Coromandel, they rage with equal if not superior violence in the southern hemisphere, particularly about the latitude of 20 degrees S., near the French islands, where many ships have been in great danger of perishing from the effects.”…

“Thus then it appears these tempests or hurricanes are tornadoes, or local whirlwinds, and are felt with at least equal violence on the sea coast, and at some middle distance out at sea. But there is a material difference in the situation of the sun when they appear at different places. On the coast of Coromandel, for example, they seldom happen, particularly to the northward, except when the sun is in the opposite hemisphere. On the Malabar coast they rage with most violence during the monsoon, whilst the sun is almost vertical. Near theisland of Mauritius they are felt in January, February and March, which may be deemed their summer months.”…

“As they happen, then, in different places at different seasons, they cannot well be ascribed, like the monsoons, to any particular situation of the sun in the ecliptic; neither, as they do not happen regularly every year, can they be deemed periodical. But, as during their continuance the wind blows all round the compass, and nevertheless is not felt in any direction of a distance of more than sixty or eighty miles, we may venture to conclude that whirlwinds are solely owing to violent and sudden changes, both in the upper and lower regions of the air. When the lower regions of the atmosphere are from any cause considerably rarified, and the air in those of the upper at the same time becomes very much condensed, according to the principle of gravity the air in the upper regions will descend, and necessarily become a whirlwind, perfectly similar to that produced by sinking a heavy body in water; the parts adjacent will immediately concentre to a point, and rush with a whirling circular motion towards the bottom with great violence.”…  

– R. R. Kelkar, May 2007  

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