NEW DELHI -- Every year in the last week of June or first week of July, as if guided by an immutable force, the skies above the parched plains of northern India suddenly turn a deep, dark gray.

Within hours, they release a torrent of life-giving rain -- for crops, for reservoirs, rain to cleanse the dust and the tensions built by weeks of unrelenting 100-degree heat.

It is the onset of the monsoon, the arrival of waters sucked up from warm oceans thousands of miles away and carried on air currents until they collide with the cold gusts of the Himalayas, India's massive northern wall. Where the air currents meet, the rains fall and India measures another year of plenty.

The problem is that sometimes the currents do not meet and sometimes the rains do not come. That which should be immutable at times is not.

This year, for example, it was the end of July before the monsoon was judged to have reached Delhi, and even then only for one short rain. Meteorologists say more rain could arrive before the season is over in September, but their voices express more hope than expectation.

Normally India's rains come from the Arabian Sea onto the west coast and from the Bay of Bengal onto the east coast. The two currents merge over the North Indian plain. When either of the air flows is not strong enough or the pressures from the mountains are too strong, the monsoon becomes stalled or is sporadic, leaving pockets or sometimes large areas with too much or too little rainfall.

This year, for example, while much of the country has little or no rain, there are floods in parts of the northeast and neighboring Bangladesh.

Some scientists blame sunspots for the imbalance in precipitation, others the massive loss of the world's rain forests and yet others the so-called El Nino, a South Pacific current said to disrupt weather worldwide when it shifts.

Indian meteorologists said they had expected trouble this year when they noticed some time ago that the Pacific waters were several degrees warmer than last year. El Nino, they say, always means a bad monsoon for India. --