Goa may experience cloud bursts in the peak monsoon months of July-August this year, causing not only Panaji but many other cities to have a flood-like situation
In the rising temperatures, the SASCOF prediction of receiving good amounts of rainfall during the months of June to September in most parts of India and South Asia comes as a breather. The recent report published on the monsoon, SASCOF (South Asian Climate Outlook Forum) has predicted that Goa and Konkan region would be receiving more than average amount of rainfall compared to last year. The report has been out after studying data and inputs available through various organisations and instituted working on weather and climate.
The scorching heat this year is a cause of concern, especially in a State like Goa where the people are used to mild weather, and heavy monsoons. “In India, several states such as Maharashtra, Karnataka and Andhra Pradesh have been trying to artificially increase the precipitation over the drought areas so that agriculture and drinking water is facilitated,” states Dr M R Ramesh Kumar, meteorologist and former chief scientist at National Institute of Oceanography (NIO) Goa.
Pointing out that the artificial rain-making process has been ongoing for quite some time, and that China had done it during the recent opening ceremony of the Beijing Olympics and Americans also have been employing such techniques in Vietnam to create flash floods during the war, Dr Ramesh Kumar discloses that the Indian Institute of Tropical Meteorology at Pune has purchased an aircraft to study cloud physics in more detail and enhance our understanding of artificial rain making and rain making in the country.
The cloud physics of each region is different, and hence it is very difficult to seed a cloud, says the former scientist and briefs, “There are several types of clouds such as Cumulus, Stratus (500 metres, low clouds), Nimbus (rain cloud), Alto Cumulus, Alto Stratus (middle level 1.5 to 3 km), Cumulonimbus (vertically developing cloud) and Cirrus (10-12 km above sea level). Also there are two categories of clouds – warm and cold.”
The warm clouds, which are below 0 degree C (freezing point/level), are usually found in the tropical regions, such as India. The cold clouds are usually seen in the middle latitude countries such as the UK, Germany and USA among others. The temperature of these is above 0 degree C. “In a warm type of cloud, we have a collision and coalescence process occurring to give us the water droplets and in a cold cloud, we have ice crystal formation,” he explains.
The prerequisite for the rain making process involves availability of Cloud Condensation Nuclei (CCN) such as NACL (Sodium Chloride) and Ag I (Silver Iodide). This CCN is added to a cloud either by an aircraft or from ground based techniques such as winds etc. The second prerequisite is the cloud should be of sufficient thickness so that the cloud droplets can turn into a water droplet before it reaches the ground.
Judicious use of cloud seeding could be extremely beneficial for mankind. However, it is not possible to have total control over the results of artificial rain or make it favourable each and every time. “Sometimes it could be disastrous or could affect the neighbouring areas or states as the clouds move away from the position where they were seeded. This happens as the winds at the cloud level are dynamic and can take the cloud in any direction, which is not in the control of those who have seeded it,” says Dr Ramesh Kumar.
In addition to this, the phenomena of climate change adds on to the artificial rain making or rain seeding because the Arabian Sea has become the warmest region in the world in the recent years which has added more moisture in the atmosphere over Arabian sea area (rim countries) which are the peripheral area of Arabian Sea like Middle East countries, such as Dubai, UAE and the West Coast of India, etc.
When the rainfall is more than 10 cm in a day, we call it an intense rainfall event or cloud burst and this occurs during the monsoon season or the selected places over the Indian subcontinent such as Uttarakhand and Kerala. Kerala experienced an abnormally high rainfall in 2018, from June 1 to August 19, resulting in severe flooding in 13 out of 14 districts in the State. As per IMD data, Kerala received 2346.6 mm of rainfall during this period in contrast to an expected 1649.5 mm of rainfall which was about 42% above normal.
And in Uttarakhand, in June 2013 a mid-day cloudburst caused devastating floods and landslides, becoming the country’s worst natural disaster since the 2004 tsunami. The rainfall received that month was far greater than the rainfall the state usually received. It occurred in Mumbai too, on July 26, 2005 when the city received 94 cms of rainfall in a day which caused a flood-like situation bringing the city to a standstill.
The cloud bursts are usually the result of a cluster of Cumulonimbus clouds which give plenty of rainfall and cause deluge over the selective area. Goa had experienced such a scenario in the month of July 2023 when we had active monsoon conditions. And it is likely that Goa may experience similar cloud bursts in the peak monsoon months of July-August 2024, causing not only Panaji but many other cities to have flood like situation when the La Nina prevails over the eastern equatorial Pacific Ocean, warns the meteorologist.
