Monsoon onset over Kerala delayed

• The India Meteorological Department (IMD) has said that the arrival of the southwest monsoon over Kerala has been delayed to June 3.
• However, Skymet, a private weather forecast agency, said the monsoon had arrived as two of the three criteria defined by the IMD had been met.

These criteria are:

1. Rain-bearing westerlies being at a minimum depth and speed.
2. At least 60% of the available 14 stations in Kerala and coastal Karnataka reported rainfall of 2.5 mm or more for two consecutive days after May 10.
3. certain degree of clouding, indicated by a parameter called outgoing longwave radiation (OLR), being below 200 W/square metre.

• Currently, IMD’s own data indicated that except for the OLR, the other criteria were met.
• Thus, there is an element of subjectivity in arrival.

Generally, across the world, the monsoons are experienced in the tropical area roughly between 20° N and 20° S.

• The climate of India is described as the ‘monsoon’ type.
• In Asia, this type of climate is found mainly in the south and the southeast.
• Out of a total of 4 seasonal divisions of India, monsoon occupies 2 divisions, namely.

1. The southwest monsoon season - Rainfall received from the southwest monsoons is seasonal in character, which occurs between June and September.
2. The retreating monsoon season - The months of October and November are known for retreating monsoons.