{"id":3582,"date":"2021-08-02T15:37:38","date_gmt":"2021-08-02T22:37:38","guid":{"rendered":"http:\/\/rammb.cira.colostate.edu\/training\/visit\/blog\/?p=3582"},"modified":"2026-03-06T09:06:25","modified_gmt":"2026-03-06T16:06:25","slug":"how-far-north-can-we-see-sun-glint-in-goes-satellite-imagery","status":"publish","type":"post","link":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/2021\/08\/02\/how-far-north-can-we-see-sun-glint-in-goes-satellite-imagery\/","title":{"rendered":"How far north can we see sun glint in GOES satellite imagery?"},"content":{"rendered":"<p><em>By Bernie Connell and Erin Sanders<\/em><\/p>\n<p>Sun glint is an optical phenomenon that can be seen in visible and near-IR satellite imagery over water features such as ocean, lakes, and rivers.\u00a0 Its presence depends on the geometry between Sun, Earth, and satellite viewing angle.\u00a0 When sunlight is reflected off water features towards the satellite sensor at nearly equal angles, this type of reflection is called specular reflection.<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-3592 aligncenter\" src=\"http:\/\/rammb.cira.colostate.edu\/training\/visit\/blog\/wp-content\/uploads\/2021\/07\/SpecularReflectionDiagram-300x230.png\" alt=\"\" width=\"300\" height=\"230\" srcset=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/SpecularReflectionDiagram-300x230.png 300w, https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/SpecularReflectionDiagram.png 626w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>How far north can we see sun glint?\u00a0Sun glint is a common occurrence in the tropics and is typically seen in daytime satellite imagery between 30\u00baN and 30\u00baS.\u00a0 The following examples show sun glint at latitudes higher than 30\u00baN during northern hemisphere summer using visible imagery in the red part of the spectrum (0.64 \u03bcm).\u00a0 The first animation shows imagery from the GOES-17 satellite located at 137.2\u00b0W in the early hours between sunset and sunrise on July 21, 2021.\u00a0 From this perspective, a seasoned eye may discern the pattern of sun glint areas appearing to travel north and eastward with the changing angle of the sun.<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-1\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_arctic_sunset_sunrise_glint_20210721.mp4?_=1\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_arctic_sunset_sunrise_glint_20210721.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_arctic_sunset_sunrise_glint_20210721.mp4<\/a><\/video><\/div>\n<p><em>GOES 17 &#8211; Arctic sunset and sunrise on July 21, 2021 from 8:30-10:30 UTC.<\/em><\/p>\n<p>Let\u2019s zoom in on a few of these regions and take a closer look.\u00a0 From this perspective the regions of sun glint are easier to spot.\u00a0 As the Sun, water surface, and satellite geometry changes, areas of brightness appear and then disappear in less than an hour.<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-2\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunset_glint_20210721.mp4?_=2\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunset_glint_20210721.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunset_glint_20210721.mp4<\/a><\/video><\/div>\n<p><em>GOES 17 &#8211; Arctic sunset on July 21, 2021 from 8:10-9:20 UTC.<\/em><\/p>\n<p>These areas of sun glint indicate relatively calm waters with a smooth surface to reflect sunlight, much like a mirror.\u00a0 The increase in reflected solar energy that reaches the satellite sensor can saturate the image as seen by the bright white swaths.\u00a0 However, not all water surfaces reflect sunlight equally.\u00a0 Winds cause rougher water and waves that will scatter sunlight in multiple directions and appear darker, as less sunlight will be directed to the satellite sensor.\u00a0 Cloud cover will also obscure any water surface below.\u00a0 Both of these can lead to patchy areas of sun glint in satellite imagery.\u00a0 Can you differentiate between calm water, rough water, and cloud cover in the next two examples?<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-3\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint1_20210721.mp4?_=3\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint1_20210721.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint1_20210721.mp4<\/a><\/video><\/div>\n<p><em>GOES 17 &#8211; Arctic sunrise on July 21, 2021 from 9:00-9:50 UTC.<\/em><\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-4\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint2_20210721.mp4?_=4\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint2_20210721.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G17_sunrise_glint2_20210721.mp4<\/a><\/video><\/div>\n<p><em>GOES 17 &#8211; Arctic sunrise on July 21, 2021 from 9:20-10:20 UTC.<\/em><\/p>\n<p>The following set of animations show sun glint detected by GOES-16 located at 75.2\u00b0W on July 26, 2021.\u00a0 We will again start with the full view from sunset to sunrise, and then focus on two examples.<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-5\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_arctic_sunset_sunrise_glint_20210726.mp4?_=5\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_arctic_sunset_sunrise_glint_20210726.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_arctic_sunset_sunrise_glint_20210726.mp4<\/a><\/video><\/div>\n<p><em>GOES 16 &#8211; Arctic sunset and sunrise on July 26, 2021 from 3:30-6:30 UTC.<\/em><\/p>\n<p>Zooming in over the Pacific Ocean off the western coast of the United States shows the contrast between the extensive bright glint area and darker surrounding areas of cloud.\u00a0 The sun glint can be seen well above 40\u00baN.<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-6\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunset_glint_20210726.mp4?_=6\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunset_glint_20210726.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunset_glint_20210726.mp4<\/a><\/video><\/div>\n<p><em>GOES 16 &#8211; Arctic sunset on July 26, 2021 from 3:30-4:20 UTC.<\/em><\/p>\n<p>Sun glint highlights areas of calm water and can reveal details about the water surface and its reflective properties.\u00a0 In this next example, it also shows the ocean-land boundary with Greenland to the north.\u00a0 Sun glint appears on the water surface but not land, although land can certainly influence wind patterns over the water surface and affect how the light is reflected.<\/p>\n<div style=\"width: 1920px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-3582-7\" width=\"1920\" height=\"1080\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunrise_glint_20210726.mp4?_=7\" \/><a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunrise_glint_20210726.mp4\">https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-content\/uploads\/sites\/5\/2021\/07\/G16_sunrise_glint_20210726.mp4<\/a><\/video><\/div>\n<p><em>GOES 16 &#8211; Arctic sunrise on July 26, 2021 from 4:40-5:30 UTC.<\/em><\/p>\n<p>So how far north can we see sun glint in GOES satellite imagery? \u00a0It is clearly seen above 75\u00baN on this day!\u00a0 The latitudinal extent of where sun glint can be seen has a seasonal dependence.\u00a0 In the northern hemisphere it can be spotted between the vernal equinox (~20 March) and the autumnal equinox (~22 September).\u00a0 The summer solstice (~20 June) is when we would expect sun glint to be seen the farthest north of the equator based on the positioning of the Sun, Earth, and satellite.<\/p>\n<p>Notice the unexpected.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>By Bernie Connell and Erin Sanders Sun glint is an optical phenomenon that can be seen in visible and near-IR satellite imagery over water features such as ocean, lakes, and rivers.\u00a0 Its presence depends on the geometry between Sun, Earth, and satellite viewing angle.\u00a0 When sunlight is reflected off water features towards the satellite sensor <a href=\"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/2021\/08\/02\/how-far-north-can-we-see-sun-glint-in-goes-satellite-imagery\/\" class=\"more-link\">Continue Reading<\/a><\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47,28],"tags":[],"class_list":["post-3582","post","type-post","status-publish","format-standard","hentry","category-geostationary-satellite-discussion","category-satellites"],"_links":{"self":[{"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/posts\/3582","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/comments?post=3582"}],"version-history":[{"count":2,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/posts\/3582\/revisions"}],"predecessor-version":[{"id":6026,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/posts\/3582\/revisions\/6026"}],"wp:attachment":[{"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/media?parent=3582"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/categories?post=3582"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rammb2.cira.colostate.edu\/visit-blog\/wp-json\/wp\/v2\/tags?post=3582"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}