{"id":541,"date":"2015-01-11T19:49:05","date_gmt":"2015-01-11T19:49:05","guid":{"rendered":"http:\/\/bluemarble.ch\/wordpress\/?p=541"},"modified":"2025-11-21T13:29:26","modified_gmt":"2025-11-21T13:29:26","slug":"the-darkest-spot-in-switzerland","status":"publish","type":"post","link":"https:\/\/bluemarble.ch\/wordpress\/2015\/01\/11\/the-darkest-spot-in-switzerland\/","title":{"rendered":"The Darkest Spot in Switzerland"},"content":{"rendered":"<p>By analysis of our MeteoSwiss high quality <a title=\"Solar Radiation Climatology in Switzerland\" href=\"http:\/\/www.meteoswiss.admin.ch\/home\/climate\/past\/solar-energy.html\" target=\"_blank\" rel=\"noopener noreferrer\">satellite-based solar irradiance maps<\/a>\u00a0created by the Heliomont algorithm I&#8217;ve found that the sunniest place in Switzerland is close to the<a title=\"Monte Rosa Hut\" href=\"http:\/\/www.neuemonterosahuette.ch\/\" target=\"_blank\" rel=\"noopener noreferrer\"> Monte Rosa<\/a> hut of the Swiss Alpine Club SAC. During\u00a0the calculation of the Solar Atlas of Switzerland (to be published as &#8220;The\u00a0Solar Cadaster of Switzerland&#8221;\u00a0on the <a title=\"BGDI\" href=\"http:\/\/map.geo.admin.ch\" target=\"_blank\" rel=\"noopener noreferrer\">Geoportal of the Swiss Government<\/a>) I have also detected the absolutely DARKEST spot in Switzerland. Here it is:<\/p>\n\n<!-- iframe plugin v.6.0 wordpress.org\/plugins\/iframe\/ -->\n<iframe loading=\"lazy\" src=\"http:\/\/map.geo.admin.ch\/?X=93050&#038;Y=636125&#038;zoom=7&#038;crosshair=bowl\" width=\"100%\" height=\"500px\" scrolling=\"yes\" class=\"iframe-class\" frameborder=\"0\"><\/iframe>\n\n<p>The point lies at <a href=\"http:\/\/map.geo.admin.ch\/?X=93050.00&amp;Y=636125.00\" target=\"_blank\" rel=\"noopener noreferrer\">636125 \/\u00a093050<\/a> (CH1903 \/ LV03 coordinate system) at the border between Switzerland and Italy. It has as sky view factor of 0.003. This is about the same sky view as found in a bottomless pit. There is no solar irradiance getting down there. The yearly mean solar irradiance is around 0.5 W m-2 (Watts per square meter; the average over most of Switzerland is well over 150 W m-2). The reason for this low predicted solar irradiance can be found in the Swiss elevation model <a title=\"DHM25\" href=\"http:\/\/www.swisstopo.admin.ch\/internet\/swisstopo\/en\/home\/products\/height\/dhm25.html\" target=\"_blank\" rel=\"noopener noreferrer\">DHM 25<\/a> at the spatial resolution of 25 m. These are the topographic elevations (m) of the darkest point including its 8 neighboring points:<\/p>\n<p>2996 2622 3414<br \/>\n2763 <strong>2440<\/strong> 3457<br \/>\n3070 3131 3484<\/p>\n<p>The center point lies between 200 &#8211; 1000 m lower than the surrounding grid points. Is this bottomless pit in beautiful landscape reality or a digital artifact?<\/p>\n<p><strong>Update<\/strong><\/p>\n<p>The customer service of SwissTopo has kindly provided a credible answer: The darkest spot is indeed an artifact of the DHM25 dataset due to a contour line which was digitized 1000 m below its actual elevation:<\/p>\n<div><a href=\"https:\/\/bluemarble.ch\/wordpress\/wp-content\/uploads\/2015\/01\/image001.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-562\" src=\"https:\/\/bluemarble.ch\/wordpress\/wp-content\/uploads\/2015\/01\/image001.png\" alt=\"DHM25\" width=\"298\" height=\"297\" srcset=\"https:\/\/bluemarble.ch\/wordpress\/wp-content\/uploads\/2015\/01\/image001.png 298w, https:\/\/bluemarble.ch\/wordpress\/wp-content\/uploads\/2015\/01\/image001-150x150.png 150w\" sizes=\"auto, (max-width: 298px) 100vw, 298px\" \/><\/a><\/div>\n<div><\/div>\n<div>Swisstopo also notes that the point of interest is located just outside the Swiss border. Swisstopo suggests to discontinue the use of the DHM25 elevation dataset in favor of the\u00a0<span class=\"Apple-style-span\"><a href=\"http:\/\/www.swisstopo.admin.ch\/internet\/swisstopo\/en\/home\/products\/height\/swissALTI3D.html\" target=\"_blank\" rel=\"noopener noreferrer\">swissALTI3D<\/a> dataset. DHM25 is however convenient since it extends across the Swiss borders. A feature which is for instance needed for Terrain horizon calculations.\u00a0My current fix is to limit sky view in natural terrain to values above 0.5 (it may be lower in urban environments). In a next step swissAlti3D could be joined with high resolution topography datasets of surrounding countries.\u00a0<\/span><\/div>\n<div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>By analysis of our MeteoSwiss high quality satellite-based solar irradiance maps\u00a0created by the Heliomont algorithm I&#8217;ve found that the sunniest place in Switzerland is close to the Monte Rosa hut of the Swiss Alpine Club SAC. During\u00a0the calculation of the Solar Atlas of Switzerland (to be published as &#8220;The\u00a0Solar Cadaster of Switzerland&#8221;\u00a0on the Geoportal of &hellip; <\/p>\n<p><a class=\"more-link btn\" href=\"https:\/\/bluemarble.ch\/wordpress\/2015\/01\/11\/the-darkest-spot-in-switzerland\/\">Continue reading<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[55],"tags":[118,117,121,116,115,120,119],"class_list":["post-541","post","type-post","status-publish","format-standard","hentry","category-meteoswiss","tag-dark-spot","tag-elevation-model","tag-meteoswiss","tag-sky-view","tag-solar-irradiance","tag-swisstopo","tag-switzerland","item-wrap"],"_links":{"self":[{"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/posts\/541","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/comments?post=541"}],"version-history":[{"count":15,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/posts\/541\/revisions"}],"predecessor-version":[{"id":856,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/posts\/541\/revisions\/856"}],"wp:attachment":[{"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/media?parent=541"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/categories?post=541"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bluemarble.ch\/wordpress\/wp-json\/wp\/v2\/tags?post=541"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}