Some climatological aspects of thunderstorms and squalls over Guwahati Airport

Abstract

Lkkj & xqokgkVh gokbZ vM~Ms ij vk, paMokr ls tqM+s okf"kZd vkSj ekfld ckjEckjrk dk forj.k] xtZ ds lkFk vk, rwQkuksa vkSj paMokrksa ds vkjEHk gksus dk le; vkSj mudh vof/k rFkk i;kZoj.kh; ifjorZuksa dk fo’ys"k.k fd;k x;k gSA rwQku vkSj paMokr lcls T;knk ebZ ds eghusa esa vkrs gSa vkSj mlds ckn viSzy ds eghus esa vkrs gSaA rwQkuksa vkSj paMokrksa dh vko`fr;k¡ lcls T;knk ebZ ds eghusa esa gksrh gSa vkSj mlds ckn vizSy ds eghus esa gksrh gSaA vf/kdk¡’k rwQku ekulwu _rq ls iwoZ vkSj ekulwu _rq ds nkSjku vkrs gSa rFkk paMokr Qjojh ls ebZ ds eghuksa ds nkSjku vkrs gSaA ekulwu _rq ls iwoZ vkus okys vf/kdk¡’k rwQku e/; jkf= ls ysdj rM+ds lqcg ds le; esa vkrs gSa tcfd ekulwu _rq ds nkSjku vkus okys rwQku 0600&1200 ;w- Vh- lh- ds chp vk;k djrs gSa vf/kdk¡’k rwQkuksa dh vof/k rhu ?kaVksa ls Hkh de dh gksrh gSA vf/kdk¡’k paMokrksa dh vof/k pkj feuVksa ls Hkh de dh gksrh gS] fn’kk mÙkj if’pe vkSj ;s 0900&2100 ;w- Vh- lh- ds le; vkrs gSaA xqokgkVh gokbZ vM~Ms ij paMokr ds vkus ls i;kZoj.kh; rkieku vkSlru 2-2° lsa- rd fxj tkrk gS] lkisf{kd vknzZrk 8-5 izfr’kr rd c<+ tkrh gS vkSj nkc 1-6 gSDVkikLdy rd c<+ tkrk gSA xqokgkVh gokbZ vM~Ms ij paMokr ds vkus ls vf/kdre iou xfr vkSlru yxHkx 39 ukWV~l gksrh gSA fiNys v/;;uksa ls rqyuk djus ij ;g irk pyrk gS fd fiNys dqN o"kksZa esa rQkuksa vkSj paMokrksa ds y{k.kksa esa fo’ks"k ifjorZu ugha vk;k gSA
 The annual and monthly frequency distribution, time of commencement and duration of thunderstorms & squalls and environmental changes associated with occurrence of squall at Guwahati Airport have been analyzed. The frequencies of thunderstorms and squalls are maximum in the month of May followed by April. Most of the thunderstorms occur during premonsoon and monsoon season and squalls occur during Feb-May. Most of the premonsoon thunderstorms commence during midnight to early morning while the thunderstorms during monsoon season have preference to commence between 0600-1200 UTC. Majority of thunderstorms is of the duration of less than three hours. Majority of squalls have the duration of less than four minutes, direction as northwesterly and occur during 0900-2100 UTC. On the average, environmental temperature falls by 2.2° C, the relative humidity rises by 8.5%, and the pressure increases by 1.6 hPa due to squall over Guwahati Airport. The average maximum wind speed associated with a squall over Guwahati Airport is about 39 knots. Comparison with the past studies indicates that characteristics of thunderstorms and squalls have not changed significantly over the years.

An inclusive study of lightning at various temporal resolutions over North East India using hi-res satellite data

“…The same study also observed 'the form taken by the convection is influenced by the land surface conditions underlying the moist flows, indicating that the terrain plays a key role in releasing and enhancing the convection' [64,71]. Apart from these studies, it is well documented that over NEIN cumulonimbus clouds are developed on almost all days during the monsoon season [38,72].…”

Trends of lightning flash density over India during different seasons

“…Further, during this season, high lightning activity is observed over the foothills of the Himalayas, the east coast of India and the Kerala coast. The northeastern part of India is known to experience very severe thunderstorms during the pre-monsoon season, locally known as "Nor'wester" (Kumar & Mohapatra, 2006). The airflow over Gangetic plains and the adjoining areas has a shallow layer of moist southerlies/southwesterly from the Bay of Bengal near the ground and dry westerlies of continental origin above.…”

Space–time variation of large hail‐producing mesoscale convective systems over a complex terrain of the Indian subcontinent as revealed by the integrated Tropical Rainfall Measuring Mission and Global Precipitation Measurement observations

“…Multiscale interaction of circulation with local topography plays an important role in shaping the weather and climate in this region (Goswami et al ., 2010). This region is highly vulnerable to the occurrence of extreme weather events such as heavy rainfall, hail, lightning, and strong wind during the premonsoon season (March through May) (Koteswaram and Srinivasan, 1958; Sen and Basu, 1961; Chaudhury and Banerjee, 1983; Ono, 1998; Karmakar and Alam, 2006; Kumar and Mohapatra, 2006; Yamane et al ., 2009; Dalal et al ., 2012; Mahanta et al ., 2013; Choudhury et al ., 2016; Mahanta and Yamane, 2020; Biswasharma et al ., 2021), causing fatalities and damage to agriculture as well as to property (De et al ., 2005; Bhardwaj et al ., 2017). Hailstorms, in particular, are one of the primary contributors to these losses (Chattopadhyay et al ., 2017; Rymbai et al ., 2019; Raihan et al ., 2020).…”