This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Friday, May 4, 2018

Freak thunderstorms in India move along a trough

From the Hindustan Times, May 3, 2018.
It is probably well known by atmospheric scientists, but I had never stumbled across a chain of thunderstorms before! 
      Duststorms yesterday killed about 100 people and injured 200 more in the past day. They occurred in the provinces of Uttar Pradesh and Rajasthan in the north and northwest parts of India. The city of Agra, home of the Taj Mahal was particularly hard hit, with 36 deaths and wind speeds reaching 130 km/hour (80 mph). he Taj Mahal itself seems to have been undamaged.   Deaths seem to be due to collapsing trees and infrastructure. It is six weeks until the monsoon season and so dust is in plentiful supply. Traffic was snarled in Dehli by the dust and fifteen flights had to be diverted. In the city of Alwar, more than 100 trees were uprooted, falling on vehicles and electricity cables.
Dust storm approached Bikaner on Wednesday from here.
     According to the Hindustan Times, thunderstorms are common before the monsoon season develops, but the severity of this storm resulted from the collision of a number of factors.  To the west, Rajasthan has experienced unusually high temperatures. This condition aids moisture retention in the atmosphere and leads to the formation of larger clouds which increase the intensity of thunderstorms. To the north a low-pressure system called the Western Disturbance, carries in moisture from Eurasian water bodies which also fed into the thunderstorm system while a cyclonic circulation system over Haryana
triggered upward movement of the moisture laden warm air north of Rajasthan.  Referring to the lower blue panel in the graphic shown here, the motion of upwelling moist air feeds the thunderstorm clouds. When the clouds can not absorb all of the moisture, it rains and a downdraft forms.  When this downdraft occurs away from the updraft because of wind shear, it can create another thunderstorm, perhaps more than one.  The track of this chain from northwest to east (dashed line in the graphic) creates an extended low-pressure area along which the thunderstorms track.  The maximum impact was near the first thunderstorm in the Uttar Pradesh and Rajasthan region.
     In an apparently unrelated storm reported by Time.com, the southern east coast state of Andhra Pradesh had 36, 749 lightning strikes in 36 hours on Tuesday, with the loss of 9 lives. Last year, for comparison, there were about 30,000 lightning strikes over the entire month of May. More than 2000 people per year are killed by lightning strikes in India (compared to the U.S. where it is ~27/year).

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