Around this time every year, as the sun moves northwards and shines directly over southern Asia, the parched landscape of India responds quickly to the sun's heat. This year has been particularly vicious. April 1999 in India has been the warmest for more than half a century; temperatures have been up to 8C Celsius above normal, and in parts of the northwest of the country they have touched an unprecedented 48 Celsius.
Drought, needless to say, has begun to take its toll.
Deliverance, however, will come later this month or early next with the onset of the Indian summer monsoon.
The Indian monsoon system resembles our own sea breeze phenomenon re-enacted on a grand and continental scale. Every winter, a large Siberian anticyclone dominates the Asian continent, and the air moving around it clockwise is responsible for the dry northeasterly winds of the Indian winter monsoon.
But as the heat of the summer sun intensifies, the air over the scorched landscape expands and becomes lighter, causing a low-pressure area to develop over the continent.
Then, with the anti-clockwise motion around this low, warm moist air from the Indian Ocean is drawn in over India from the south-west. The warm humid air is forced to rise as it crosses the gently sloping Plateau of the Deccan towards the Himalayan Mountains, bringing heavy showers, thunderstorms and torrential rain. The summer monsoon lasts intermittently until late September. As the cold season reapproaches, however, the continental anticyclone over Siberia reasserts itself; the air-flow once again reverses direction, bringing the dry north-easterly winds of the winter monsoon back again to India.
The summer monsoon rejuvenates a dying landscape. As is happening at present, through each blistering spring the arid soil is baked lifeless by burning sun and desiccating winds, and inhabitants of the sub-continent move about their business at a weary, listless pace. Then, just when the heat seems insupportable, the clouds that have been piling up in the distance for some time burst open to disgorge their torrential rains upon a grateful land.
The monsoon is celebrated almost as divine deliverance. Children dance ecstatically in the heavy downpour, catching the precious drops of liquid in their open hands; the stifling heat is broken and the earth blooms in fresh green profusion. This annual phenomenon delivers in the few months of its duration about 90 per cent of the sub-continent's annual rainfall.
The rains are a vital life-giving force, and if they are delayed, or weaker than usual, the rice fields are inadequately watered, agricultural production suffers, and great hardships are visited on large sections of the local population.