Instead of pleasant mornings, the Malayalam month of Chingom is likely to be marked with humid days and foggy mornings this year with a rise in temperature and humidity.
Already, the minimum morning temperature this month has set a new benchmark due to a ‘break in monsoon’. Indicating a shift in atmospheric conditions, a thin layer of fog enveloped the plains and hilly areas on Wednesday, reducing visibility to less than 500 metres in some areas.
“If the visibility is more than 1,000 metres, it is called mist, while fog indicates visibility falling to less than 1000 metres. Also, fog is a symbol of stability in atmospheric conditions (instability used to create rainfall). The appearance of fog at this point in time indicates subdued rainfall, reducing the chances for big spells in the coming weeks,” says a senior meteorological scientist.
Madhavan Rajeevan, former Secretary, Union Ministry of Earth Sciences, says this is one of the most prolonged ‘monsoon break spells’ in the country. The ‘break in monsoon’ has crossed 10 days this year and the condition is likely to persist for at least two more days. The longest break spell was between 18 July and 3 August in 1972, a deficient year. In July 2002, there were 24 break days (with intervals), he says.
The movement of the monsoon trough — an elongated low pressure zone from the heat low of northwest India with its axis running parallel to the Himalayan mountains in a west-to-east direction — causes ‘break in monsoon’ conditions.
When the trough moves north of its original position, rain ceases abruptly over the plains of northern India and south but increases equally rapidly in intensity over the foothills of northeast India. This is called a ‘break in monsoon’. And when it moves south of its original position, conditions become favourable for the formation of low pressure and depression over the Bay of Bengal, bringing more rain to central India and southern peninsula.
In the coming week, the eastern end of the trough is likely to move southward. As a result, rain is likely to move from east to west in a staggered manner. However, it is unlikely to break the jinx of weak weather activity continuing for the past 10 days in Kerala, according to Skymet Weather. In Kerala, the August temperature has already increased due to the prolonged break spell.