New Delhi — It has now become almost habitual that as soon as a cloud passes over the sun , Indians begin staring upward, praying that the rains will come. In the town of Kanniyakumari in the southern state of Tamil Nadu, eight priests stood in waist-deep water in two rusted tanks and, in age-old custom, invoked the Hindu rain god Varuna to bring long overdue rains.
In the neighboring state of Kerala, where coconuts are the largest cash crop, nearly half of this year's anticipated yield now lies in ruins - a loss of $75 million.
In Darjeeling, the larger of the two lakes at Sinchal has long since gone dry. And all but one of the 26 mountain springs which normally flow from the snow-capped Himalayas have gone dry as well. Water supply to this once-lush region of tea plantations has now been cut to one 45-minute period every 24 hours.
From the southernmost tip of India, where the Arabian Sea meets the Bay of Bengal, to the foothills of the Himalayas, an estimated 75 percent of this nation is today gripped by drought. Fifteen of India's 22 states are affected, as are 262 million of its 700 million people.
The most severely affected regions are in eastern India and in western Rajasthan, where the rains have failed, in most cases, for the last three to five years. In the northern wheat-growing areas, unseasonal, torrential rains have ruined vast wheat fields, reminding development experts across the country of India's continuing vulnerability to natural disasters.
The nation's ''green revolution,'' meant to give India self-sufficiency in food, has been badly stunted. Grain imports could reach 5-8 million tons this year, siphoning off some $1 billion in badly needed foreign exchange.
''But,'' said one Western expert, ''even though this drought has the dimensions of the great drought of the 1960s, India will never again see the specter of famine which haunted the country then. . . . Nor will the government have the humiliating experience of having to appeal to the international community for immediate relief.''
It was, in fact, the drought of the 1960s that forced India to finally cope with its massive food problems. The groundwork for the ''green revolution'' was laid. And today there are foodstocks within the country; there is a far better road system; and there are ''food for work'' programs. Perhaps as important as any other single factor, however, is that India's often-sluggish bureaucracy seems able to cope.
Far more remains to be done, however, than the $554 million allocated for drought relief.
For instance, in the nation's third largest city of Madras, 4.5 million people are now dependent on water brought in largely by railway and convoys of trucks. The city's normal consumption of water is 80 million gallons a day. It is now functioning on 20 million gallons a day.
Beneath Madras, however, is all the water it needs. There are vast deposits of good ground water, according to United Nations officials, but no wells have been dug - a project that should have begun in 1980 when the first monsoon failed to come. Regional governments are blaming the federal government for such lost opportunities, while federal officials privately chafe that had regional governments not attempted to be so independent, projects could now be under way.
The truth probably lies somewhere in between. There is now a sprinkling of joint state and federal programs to surround Madras with vast banks of trees and to divert available river waters. But Tamil Nadu's most ambitious project is with neighboring Andhra Pradesh to divert drinking water from the Krishna River. Once the project is funded, however, its completion will take at least six years.
Yet, whether in Madras or in the parched wasteland of western Rajasthan, neither the government nor the rain gods can totally carry the blame. As India's population continues to grow by 13 million a year, no amount of rainfall and no amount of carefully laid government plans will be able to provide for this nation on a guaranteed basis, according to Western observers.
There is thus a harsh reality to the Hindu lettering painted on the sides of Rajasthan's water trucks: ''If you do not check the growth of your family, the cattle will go thirsty.'' It is a measure of the state government's concerted plan to push ahead with a birth control program in India's most devastated, drought-affected land. Seventy percent of Rajasthan's 33,000 villages do not have enough to eat or drink today. In that state, at least 120 people died of malnutrition in February and March - the only current statistics available on fatalities connected with the drought.
It has been five years since Rajasthan has had any appreciable rain. Long lines of solitary people, in scenes reminiscent of ''The Grapes of Wrath,'' move out in a mass exodus to neighboring Haryana and Madhya Pradesh. In some areas, cattle are being sold for one dollar a head. More entrepreneurial grazers have begun smuggling their cattle across the Pakistan frontier, where, if they are fortunate, they can fetch $50 a head.
Through all this, one thing that strikes a foreigner is that Indians, at least for the moment, appear to be taking everything in stride.
Madras remains a remarkably normal city, as inhabitants line up daily in snake-like water lines. Agitation by India's normally docile farmers, which flared last year in Maharashtra and Karnataka states, has not been galvanized, or emulated elsewhere during the crippling drought. Only in Bihar state have there been limited demonstrations, and in Tamil Nadu some 5,000 farmers recently courted arrest to protest the drought conditions and inadequate government relief.
Thus, the rainmakers continue their dances. And Indians take hope from unseasonal May showers that the monsoons may come this year. But even if they come in abundance and immediate human suffering is relieved, it will take two to three years, according to experts, for the damage to be reversed.
And that will be only if the June to September monsoons really do come.