{"id":31500,"date":"2019-01-25T12:00:05","date_gmt":"2019-01-25T12:00:05","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=31500"},"modified":"2019-01-28T02:55:36","modified_gmt":"2019-01-28T02:55:36","slug":"pyrocumulonimbus-cloud-in-australia","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/31500","title":{"rendered":"PyroCumulonimbus cloud in Australia"},"content":{"rendered":"

\"Himawari-8<\/a>

Himawari-8 “Red” Visible (0.64 \u00b5m, top),<\/em> Shortwave Infrared (3.7 \u00b5m, middle)<\/em> and Infrared Window (10.3 \u00b5m, bottom)<\/em> images [click to play to animation | MP4<\/strong><\/a>]<\/p><\/div>JMA<\/strong><\/a> Himawari-8 “Red” Visible (0.64 \u00b5m), Shortwave Infrared (3.7 \u00b5m) and Infrared Window (10.3 \u00b5m) images (above)<\/strong><\/em> showed the development of a pyroCumulonimbus (pyroCb) cloud from a bushfire that was burning in the eucalypt forests of eastern Victoria, Australia on 25 January 2019. A rapid-scan “Target” sector was positioned over the region beginning at 0522 UTC, providing images every 2.5 minutes (instead of the routine 10-minute interval). Cloud-top infrared brightness temperatures became colder than -40\u00baC (the threshold for pyroCb classification)<\/em> after 0230 UTC, and eventually cooled to around -55\u00baC (orange enhancement)<\/em>. This temperature roughly corresponded to an altitude around 12 km, according to nearby Melbourne rawinsonde data (plot<\/strong><\/a> | text<\/strong><\/a>).<\/p>\n

A closer view of Himawari-8 “Red” Visible (0.64 \u00b5m) and Shortwave Infrared (3.7 \u00b5m) images (below)<\/strong><\/em> revealed the rapid southeastward run of the fire, as shown by the growth of the “hot spot” (black to red pixels)<\/em> on Shortwave Infrared images. The darker gray appearance of the pyroCb cloud is due to the presence of smaller ice crystals at the cloud top — these smaller ice crystals are more efficient reflectors of incoming solar radiation, making the cloud tops appear warmer<\/em> than those of conventional cumulonimbus. Vigorous updrafts driven by the intense heat of the fire limit the in-cloud residence time for ice crystal growth, which leads to smaller particles being ejected at the pyroCb cloud top.<\/p>\n

\"Himawari-8<\/a>

Himawari-8 “Red” Visible (0.64 \u00b5m, left)<\/em> and Shortwave Infrared (3.7 \u00b5m, right)<\/em> images [click to play to animation | MP4<\/strong><\/a>]<\/p><\/div>In a comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 \u00b5m) images from Suomi NPP (at 0311 UTC<\/strong><\/a>) and NOAA-20 (at 0501 UTC<\/strong><\/a>) images viewed using RealEarth<\/strong><\/a> (below)<\/strong>,<\/em> cloud-top infrared brightness temperatures were in the -55 to -58\u00baC range (darker shades of orange)<\/em>.<\/p>\n

\"VIIRS<\/a>

VIIRS True Color RGB and Infrared Window (11.45 \u00b5m) images from Suomi NPP (0311 UTC) and NOAA-20 (0501 UTC) images [click to enlarge]<\/p><\/div>\n

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Large bushfire in #EastGippsland<\/a> producing a huge plume of smoke this afternoon stretching over eastern Bass Strait. Check out the satellite picture at https:\/\/t.co\/9md40P2b4k<\/a> pic.twitter.com\/5ceZV5nf0T<\/a><\/p>\n

\u2014 Bureau of Meteorology, Victoria (@BOM_Vic) January 25, 2019<\/a><\/p><\/blockquote>\n