Rain dance

In the last 108 years, since the IMD has been keeping records, it is indeed the earliest arrival of the monsoon over Delhi and northern and central India. There have been instances of the monsoon reaching Delhi a week in advance, even on June 17, as in 1998, but this year has been the earliest.

•What is the normal date of arrival of the monsoon in India and how much does it vary?

The monsoon arrives on the Kerala coast on June 1 from where it branches off into the Arabian Sea branch and the Bay of Bengal branch. It normally takes a month to spread over the entire country. The expected arrival of the monsoon over Mumbai is June 10 and in Delhi it is June 29. But there are yearly variations in these dates, sometimes ranging over a week.

•This year the arrival at the Kerala coast was on schedule. How did it, then, reach other parts of the country so quickly?

The monsoon reached the Andaman and Nicobar islands as early as May 10, five days ahead of schedule. But the onset in Kerala was close to normal, on May 31. Thereafter, the advance upwards has been very rapid. The southern peninsula and the north-eastern states had been covered by June 2. Mumbai received monsoon showers on June 7 and by June 10 the west coast and south Gujarat were under monsoon cover.

Generally, the advance of the monsoon happens in phases. Scientists say this year one strong surge has been enough to push the monsoon to most parts of the country — leaving out only the extreme northwest.

•Does it mean more rain this year?

As of now, scientists are treating it as an isolated event that has shown a departure from the routine. The IMD has predicted normal rainfall for the four-month season and is sticking to it.

•How much rain does India normally get in the monsoon?

Based on data from 1941-1990, the average rainfall in the country during the four-month monsoon season is 89 cm. The IMD calls it Long Period Average (LPA). This is more than 80 per cent of the rains India receives in a year.

•What will be the impact of an early monsoon on agriculture and other sectors?

Agriculture will benefit, as early rains would encourage the farmers to go in for early sowing of kharif crops. Irrigation costs will go down which would be a big relief for farmers. The power sector will find itself in a happy situation with enough water in the reservoirs. The drop in temperatures is also likely to boost tourism.

•Is it climate change?

For now, scientists are treating it only as an unusual event. It does not fit into any overall pattern of early arrival of rainfall. This year has been extra wet globally with the US and Europe also experiencing unusually large amounts of rainfall in the summer. Southern China is facing devas-tating floods. India itself has been receiving above average rainfall in the last couple of months, with May being one of the wettest in many years. All this does indicate a changing climate but it is too early to establish a direct link.

amitabh.sinha@expressindia.com