India, its administration & progress / Sir John Strachey.

John Strachey

Date:: 1903

Catalogue details

Licence: In copyright

Credit: India, its administration & progress / Sir John Strachey. Source: Wellcome Collection.

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and their consequences, especially in regard to the winds and the rainfall, show us, as Mr. Blanford says, “ how each season in succession affects in diverse modes the different portions of the country; why one province may sometimes be devastated by flood while another is parched with drought, and why, with special adapta- tion to the peculiarities of its own seasons and resources, each of them has its own agricultural system, its own staples, its own rotation of crops.” After March the heat in Northern India rapidly increases. As the air above the heated earth becomes hotter, the pressure becomes less. At the same time an increase of pressure is going on over the ocean south of the equator, which has then its winter. Thus, a cur- rent of air laden with moisture is gradually established towards the continent of India from the sea. This is the so-called south-west monsoon, which brings the periodical rains every year to India, when the heat of the summer has reached its greatest intensity. To- wards the end of May the monsoon has usually become established in the south-western extremity of India, and before the end of June it has extended to the greater part of the northern provinces. The quantity of rain that falls in any part of India depends mainly on the configuration of the surface of the land, and on its situation with reference to the vapour-bearing winds. As the amount of watery vapour which air can hold in suspension varies with the temperature of the air, and increases with the tem- perature, any cause which cools the current from the sea leads to condensation of the vapour and to the fall of rain. One of the chief of such causes is the existence of mountains which stand in the path of the winds, and

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