{"id":4204,"date":"2026-10-05T08:48:41","date_gmt":"2026-10-05T08:48:41","guid":{"rendered":"https:\/\/kingmakersiasacademy.com\/current-affairs\/?p=4204"},"modified":"2026-10-06T08:52:39","modified_gmt":"2026-10-06T08:52:39","slug":"terrestrail-stilling","status":"publish","type":"post","link":"https:\/\/kingmakersiasacademy.com\/current-affairs\/terrestrail-stilling\/","title":{"rendered":"Terrestrail Stilling"},"content":{"rendered":"<table style=\"font-size: 16px; font-style: normal;\">\n<tbody>\n<tr>\n<td>\n<blockquote><p><b>SYLLABUS: Geography<\/b><\/p>\n<p><b>General Studies \u2013 : I<\/b><span style=\"font-weight: 400;\"> Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, Cyclone etc., geographical features and their location-changes in critical geographical features and in flora and fauna and the effects of such changes.&#8221;<\/span><\/p><\/blockquote>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><b>IN NEWS:<\/b><span style=\"font-weight: 400;\"> Letting the wind flow freely is the secret to cooling our cities<\/span><\/p>\n<p><b>QUESTION: <\/b><span style=\"font-weight: 400;\">What is terrestrial stilling? Discuss its possible implications for heat stress, evaporation and air-pollution dispersion in rapidly urbanising Indian cities.<\/span><\/p>\n<p><b>ANSWER: <\/b><b>Terrestrial stilling<\/b><span style=\"font-weight: 400;\"> refers to the observed global decline in surface wind speeds over land masses over recent decades. Driven by factors including climate-change-induced shifts in atmospheric circulation and increased land surface roughness\u2014primarily from expanding forest cover and rapid urban infrastructure\u2014this phenomenon significantly alters microclimates, particularly across dense urban environments.<\/span><\/p>\n<h3><b>Implications for Heat Stress in Rapidly Urbanising Indian Cities<\/b><\/h3>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Reduction in Evaporative and Convective Cooling:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Lower surface wind speeds diminish the rate of heat exchange between the human body and the surrounding air. In high-humidity tropical and sub-tropical Indian cities (such as Mumbai, Chennai, and Kolkata), reduced wind movement severely hampers sweat evaporation, elevating the perceived temperature and heat index.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Exacerbation of Urban Heat Island (UHI) Effect:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Reduced wind speeds limit the ventilation of trapped heat within dense urban canyons built from concrete and asphalt. This stagnation prolongs high surface temperatures into the night, hindering overnight cooling and increasing the frequency of severe urban heat stress events.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Heightened Public Health Vulnerabilities:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Extended exposure to stagnant, hot air during heatwaves increases heat-related morbidities\u2014such as heat exhaustion and heat stroke\u2014and elevates cardiovascular and respiratory strain, disproportionately affecting outdoor laborers and informal settlement dwellers.<\/span><\/li>\n<\/ul>\n<h3><b>Implications for Evaporation and Hydrological Dynamics<\/b><\/h3>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Decline in Evapotranspiration Rates:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Wind speed is a primary driver of atmospheric water demand. Terrestrial stilling decreases potential evapotranspiration (PET), slowing the removal of moisture from urban water bodies, open soils, and vegetated areas.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Altered Urban Water Balance and Microclimates:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">A reduction in evaporation rates alters local humidity profiles and reduces the cooling effect provided by urban wetlands and green spaces. This can disrupt the natural cooling capacity of green-blue infrastructure designed to mitigate urban heat.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Potential Shifts in Precipitation Dynamics:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Slower evaporation rates, combined with altered atmospheric convection at the local scale, can impact localized cloud formation and rainfall patterns, complicating urban storm-water management and local water security.<\/span><\/li>\n<\/ul>\n<h3><b>Implications for Air-Pollution Dispersion<\/b><\/h3>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Accumulation of Surface-Level Pollutants:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Wind acts as the primary natural vector for the transport and dilution of atmospheric pollutants. Stilling leads to atmospheric stagnation, preventing the horizontal dispersion of key pollutants like particulate matter (<\/span><span style=\"font-weight: 400;\">P<\/span><span style=\"font-weight: 400;\">M<\/span><span style=\"font-weight: 400;\">2.5<\/span><span style=\"font-weight: 400;\"> and <\/span><span style=\"font-weight: 400;\">P<\/span><span style=\"font-weight: 400;\">M<\/span><span style=\"font-weight: 400;\">10<\/span><span style=\"font-weight: 400;\">), nitrogen oxides (<\/span><span style=\"font-weight: 400;\">N<\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\">x<\/span><span style=\"font-weight: 400;\">), and sulfur dioxide (<\/span><span style=\"font-weight: 400;\">S<\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\">2<\/span><span style=\"font-weight: 400;\">).<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Severe Winter Smog and Inversion Episodes:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">In landlocked Indian cities across the Indo-Gangetic Plain (such as Delhi, Lucknow, and Patna), terrestrial stilling during winter exacerbates thermal inversion layers. The combination of low temperatures, high emissions, and weak surface winds locks hazardous pollutants near the ground, producing prolonged, severe smog episodes.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Increased Formation of Secondary Pollutants:<\/b><b><br \/>\n<\/b><span style=\"font-weight: 400;\">Stagnant air masses provide extended reaction times for primary emissions in the presence of sunlight, accelerating the formation of secondary pollutants like ground-level ozone (<\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\">3<\/span><span style=\"font-weight: 400;\">) and secondary organic aerosols, which pose severe respiratory hazards.<\/span><\/li>\n<\/ul>\n<h3><b>Wayforward:<\/b><\/h3>\n<ol>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Wind-Sensitive Urban Design:<\/b><span style=\"font-weight: 400;\"> Incorporate ventilation corridors, optimized building heights, and strategic spatial layouts to preserve natural wind paths and enhance urban air flushing.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Expansion of Blue-Green Infrastructure:<\/b><span style=\"font-weight: 400;\"> Integrate urban forests, green roofs, and interconnected wetlands to promote natural microclimate regulation despite lower ambient wind speeds.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Targeted Emission Reductions:<\/b><span style=\"font-weight: 400;\"> Strengthen source-level pollution controls under frameworks like the National Clean Air Programme (NCAP) to offset the reduced natural dispersion capacity caused by atmospheric stagnation.<\/span><\/li>\n<\/ol>\n<table>\n<tbody>\n<tr>\n<td>\n<blockquote><p><b>PYQ REFERENCE UPSC 2024<\/b><\/p>\n<p><span style=\"font-weight: 400;\">Q. &#8220;How do microclimatic variations in urban areas affect local weather patterns? Discuss with special reference to heat stress and pollution levels in major Indian cities.&#8221;<\/span><\/p><\/blockquote>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><b>SOURCE: <a href=\"https:\/\/epaper.thehindu.com\/ccidist-ws\/th\/th_international\/issues\/207546\/OPS\/G14GJAK02.1+G8MGKCLV3.1.html\" target=\"_blank\" rel=\"noopener\">The Hindu e-paper &#8211; Letting the wind flow freely is the secret to cooling our cities<\/a><\/b><\/p>\n","protected":false},"excerpt":{"rendered":"<p>SYLLABUS: Geography General Studies \u2013 : I Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, Cyclone etc., geographical features [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":4205,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[39,68,18,41],"tags":[],"class_list":["post-4204","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-daws","category-daily-current-affairs","category-geography","category-gs-1"],"_links":{"self":[{"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/posts\/4204","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/comments?post=4204"}],"version-history":[{"count":1,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/posts\/4204\/revisions"}],"predecessor-version":[{"id":4206,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/posts\/4204\/revisions\/4206"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/media\/4205"}],"wp:attachment":[{"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/media?parent=4204"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/categories?post=4204"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kingmakersiasacademy.com\/current-affairs\/wp-json\/wp\/v2\/tags?post=4204"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}