Weeks of extreme weather in India
By Kasha Patel
25 May 2018(NASA) – India has been hit by a streak of unusually intense thunderstorms, dust storms, and lightning so far in 2018. The events collapsed homes, destroyed crops, and claimed the lives of over a hundred people with even more casualties, calling for assistance by Prime Minister Narendra Modi.In late April, the state of Andhra Pradesh in southeastern India was struck by about 40,000 lightning bolts in 13 hours—more than the number of strikes that occurred in the entire month of May 2017 — striking people and livestock.On 2 May 2018, a cluster of strong thunderstorms, accompanied by strong winds and lightning, swept through the Rajasthan region in the north, knocking over large structures and harming those in the way. The potent thunderstorms whipped up one of the deadliest dust storms in decades.One week later, the same region was hit by more deadly thunderstorms that brought lightning, 110 kilometer (65 mile) per hour winds, and violent dust storms.The map above shows aerosols, including dust, over northern India on 14 May 2018, around the time of the second dust storm. The aerosol measurements were recorded by the Ozone Mapping and Profiler Suite (OMPS) on the Suomi NPP satellite. The dust is naturally blocked from moving north by the Himalayan mountain range. In addition to causing accidents and poor air quality, dust aerosols can influence the amount of heat transmitted to Earth‘s surface by either scattering or absorbing incoming sunlight.Dust storms and thunderstorms are common in India at this time, but the intensity this year appears to be anomalous. The unusual weather could have a combination of causes, including extra moisture from a cyclonic circulation over West Bengal colliding with destructive dusty winds. High temperatures in the area also made the atmosphere unstable, fueling thunderstorms and heavy winds. Some research has suggested that high temperatures in a warming world could increase the intensity of future dust storms.The unusually high number of lightning strikes was caused by cold winds from the Arabian Sea colliding with warmer winds from northern India, leading to the formation of more clouds than usual. Despite the spike in lightning this April, long–term satellite data do not show any strong trends in India, said Richard Blakeslee, an atmospheric scientist at NASA‘s Marshall Space Flight Center. India has long been prone to lightning strikes, which are believed to cause more fatalities than any other natural hazard in the country.
The second map shows the annual average number of lightning flashes in India from 1998–2013. The visualization was made from data acquired by the Lightning Imaging Sensor (LIS) on NASA’s Tropical Rainfall Measuring Mission satellite and compiled by the Global Hydrology Resource Center (GHRC). Southeastern India usually experiences increased lightning activity before monsoon season, as heating and weather patterns become unstable and changeable.Researchers are cautious about the idea that the spring 2018 weather patterns in India are the beginning of a trend. Some years happen to be highly active without signaling a longer–term trend, said Dan Cecil, a scientist at NASA Marshall. For instance, a region near Andhra Pradesh had almost double the normal lightning flash rates in 2010, yet 2011 was almost exactly normal. The following years alternated between being slightly below normal and slightly above normal.“Only time can show whether such weather patterns develop more often or regularly in the future, or if this was simply a rare, chance event,” said Blakeslee.
