(The writer is from the Faculty of Geography, in Biswanath College, Chariali. He can be reached at Email ID: firstname.lastname@example.org)
'Bordoisila' is an Assamese word native to the state of Assam in Northeastern India. The storm 'Bordoisila' is experienced every year in the Spring, pre-monsoon season, which refers to the wild wind that is accompanied by heavy rains and thunderstorms and it marks the beginning of monsoon.
Bordoisila is a typical Asomia word with its concept, which is reigning Assam from Pre-Ahom. The word 'Bordoisila' is derived from the Bodo word 'Bardoisikhla'. Bardoisikhla breaks down to 'Bar' meaning wind, 'Doi' means water and 'Sikhla' means girl in Bodo language or other Tibeto-Burman languages. It represents the spirit Goddess of Nature, wind and rain, and it marks the beginning of the festival month of Bohag or Baishagu in the spring season.
According to the local folklore of Assam, before the arrival of spring, the married woman by the name of 'Bordoisila' goes to her maternal home and mind you; she is in a hurry and hence throws everything out of her way. The action of the lady going to her mother's in a way, speaks about the spirits of the people of Assam, very eagerly waiting for the spring festival Bihu' or 'Baisakhi' to be celebrated. As the folk song says 'Bohag' the spring season comes to her mother's home, Assam disguised as 'Bordoisila'.
As the Sun shifts Northwards towards the Tropics of Cancer after the Vernal Equinox, the whole Indian land surface experiences an increase in temperature. In most parts of Northeast India including Assam, the temperature recorded is between 30 degree and 35-degree Centigrade. April, May, and June are the months of summer in North and North East India. In May, the heat belt moves further North and in North-Western parts of India, temperatures around 48 degrees Centigrade are not uncommon.
The atmospheric pressure is low over the country due to high temperature. Since the sun goes gradually towards the north during the summer solstice, the inter-tropical convergence zone begins to move towards the north reaching up to 25 degrees north latitude in June. The general direction of the wind is from the west and south-west in Northern and Northeastern India.
There are essentially short-lived thunderstorms, and bring little rainfall (torrential rain) and give much relief from the heat. Frequent dust storms are very common during March and April in Northeastern India.
Occasionally, the moisture-laden winds are attracted towards the periphery of the trough. A sudden contact between dry and moist air masses gives rise to local storms of great intensity in Assam and Northeastern India. The local storms are associated with violent winds, torrential rains and even hailstorms.
The thunderstorms, which originate over Chotanagpur Plateau are carried eastwards by Westerly winds. The area with the highest incidence of thunderstorms in the Northeastern states of Assam, West Bengal and the adjoining areas of Orissa and Jharkhand. The rainfalls brought by thunderstorms are called the Spring storm shower. The storms are often very violent with squall speed of 60 to 80 km per hour. Large size hail storms sometimes accompany the showers, and harm the animals and standing crops. The period of maximum occurrence of these storms is in the months of 'Baisakh'. These wild storms are thus in Bengal locally called 'Kal Baisakh', a calamity in the month of Baisakh. In Assam, these storms are known as 'Bardoichila'.
Many low-pressure systems of varying stages of development from the Bay of Bengal and Arabian sea and move west or north-westwards, sometimes recurring North or North-East at a later stage.
According to Meteorology, a cyclone is a large-scale mass of air that rotates around a strong centre of low atmospheric pressure. It is characterized by strong winds, thunderstorms and heavy rainfall, hailstorms. When storms develop in the Indian ocean, it is referred to as the tropical cyclones with severe cyclonic storms. The wild storm 'Bordoichila' is also a type of tropical cyclone that affects Assam as well as Northeastern India.
Indian Meteorological Department (IMD) names the cyclones that develop over the North Indian Ocean including the Bay of Bengal and the Arabian sea following standard procedures. Tropical cyclones and subtropical cyclones are named by various warning centres to provide ease of communication between forecasters and the general people regarding warning and forecasts. The names are aimed to reduce confusion in case of multiple storms in the same basin area.
During the spring season, during the pre-monsoon period, severe storms hit the state of Assam and other parts of the Northeastern region. Several properties around the state were damaged in the massive storms. The storm damaged several houses, roadside hoardings, uprooting electric poles, trees in many parts of the state. The power supply of the state snapped for several hours in a day.
The local folklore reminds us of the action of the lady 'Bordoisila' going to her mothers in a way, speaks about the spirit of the people of Assam, very eagerly waiting for the spring festival 'Bihu' or 'Baisakhi' to be celebrated. 'Bordoisila' brings in with it 'Bohag', the spring season of merriment and celebration, marking the entire state dress up its newest greens and flavour.