{"id":527,"date":"2026-05-30T08:39:57","date_gmt":"2026-05-30T08:39:57","guid":{"rendered":"https:\/\/marinersupdate.com\/blog\/?p=527"},"modified":"2026-05-30T08:39:57","modified_gmt":"2026-05-30T08:39:57","slug":"captains-weather-desk-wk-2","status":"publish","type":"post","link":"https:\/\/marinersupdate.com\/blog\/captains-weather-desk-wk-2\/","title":{"rendered":"CAPTAIN&#8217;S WEATHER DESK &#8211; WK : 2"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">THE ATMOSPHERIC PRESSURE AND TEMPERATURE<\/h2>\n\n\n\n<h2 class=\"wp-block-heading\">1. Pressure of the Atmosphere<\/h2>\n\n\n\n<p>The Earth&#8217;s atmosphere is held in place by gravity. Although gases are light, they still have weight. The closer we are to the Earth&#8217;s surface, the greater the amount of air pressing downward. This creates atmospheric pressure.<\/p>\n\n\n\n<p>At sea level, the average atmospheric pressure is about <strong>1,013.2 hPa<\/strong>. As altitude increases, atmospheric pressure decreases because there is less air above exerting weight. For example, at around <strong>3,000 m (9,850 ft)<\/strong>, atmospheric pressure reduces to approximately <strong>670 hPa<\/strong>.<\/p>\n\n\n\n<p>Atmospheric pressure is not limited to a downward force alone. It acts <strong>equally in all directions<\/strong> \u2014 upwards, downwards, and horizontally.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"416\" height=\"542\" src=\"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-1.png\" alt=\"\" class=\"wp-image-529\" srcset=\"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-1.png 416w, https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-1-230x300.png 230w, https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-1-350x456.png 350w\" sizes=\"auto, (max-width: 416px) 100vw, 416px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Key Points<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Air has weight and creates pressure.<\/li>\n\n\n\n<li>Atmospheric pressure decreases with height.<\/li>\n\n\n\n<li>Average sea-level pressure: <strong>1,013.2 hPa<\/strong><\/li>\n\n\n\n<li>Pressure at 3,000 m: <strong>about 670 hPa<\/strong><\/li>\n\n\n\n<li>Pressure acts in all directions.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">2. Heating of the Troposphere<\/h2>\n\n\n\n<p>The atmosphere is mostly transparent to the sun\u2019s short-wave radiation and receives very little direct heating from it. Instead, the <strong>Earth\u2019s surface absorbs solar energy<\/strong> and becomes warm.<\/p>\n\n\n\n<p>The layer of air in contact with the Earth is heated by this warm surface. Heat then spreads upward through three main processes:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"149\" height=\"163\" src=\"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-2.png\" alt=\"\" class=\"wp-image-530\"\/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Convection<\/h3>\n\n\n\n<p>Warm air rises and carries heat upward.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Turbulence<\/h3>\n\n\n\n<p>Mixing of air masses spreads warmth.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Conduction<\/h3>\n\n\n\n<p>Direct transfer of heat through molecular contact. This process is relatively slow.<\/p>\n\n\n\n<p>Because of these processes, the temperature of lower atmospheric layers is mainly influenced by the temperature of the Earth\u2019s surface below.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">3. Variation of Temperature with Height<\/h2>\n\n\n\n<p>Under normal atmospheric conditions, temperature <strong>decreases with increasing height<\/strong> in the troposphere. This occurs because the Earth&#8217;s surface is the primary heating source, and its warming effect is strongest near ground level.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"187\" height=\"159\" src=\"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/image-4.png\" alt=\"\" class=\"wp-image-532\"\/><\/figure>\n\n\n\n<p>This decrease in temperature continues up to the <strong>tropopause<\/strong>, which forms the boundary between the troposphere and the stratosphere. Above the tropopause, temperature patterns behave differently because surface heating and upward air movement have less influence.<\/p>\n\n\n\n<p>The <strong>average lapse rate<\/strong> in the troposphere is approximately:<\/p>\n\n\n\n<p><strong>0.6\u00b0C per 100 m<\/strong><\/p>\n\n\n\n<p><br>or<br><strong>1\u00b0F per 300 ft<\/strong><\/p>\n\n\n\n<p>However, the actual lapse rate may vary from place to place and from day to day, especially near the surface where weather and local conditions can change rapidly.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Quick Summary<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The Earth heats the air from below.<\/li>\n\n\n\n<li>Heat moves upward by convection, turbulence, and conduction.<\/li>\n\n\n\n<li>Temperature normally decreases with altitude in the troposphere.<\/li>\n\n\n\n<li>Average lapse rate: <strong>0.6\u00b0C per 100 m<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>THE ATMOSPHERIC PRESSURE AND TEMPERATURE 1. Pressure of the Atmosphere The Earth&#8217;s atmosphere is held in place by gravity. Although gases are light, they still have weight. The closer we are to the Earth&#8217;s surface, the greater the amount of air pressing downward. This creates atmospheric pressure. At sea level, [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":528,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[584],"tags":[588,638,641,594,643,592,585,461,642,272,639,637,589,586,640],"class_list":["post-527","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-captains-weather-desk","tag-atmosphere","tag-atmosphericpressure","tag-climatebasics","tag-marinetraining","tag-marineweather","tag-maritimeeducation","tag-meteorology","tag-nauticalknowledge","tag-pressureandtemperature","tag-seafarers-2","tag-stratosphere","tag-temperature","tag-troposphere","tag-weatherscience","tag-weatherstudy"],"featured_image_src":"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/CAPTAIN-COVER-1024x576.png","blog_images":{"medium":"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/CAPTAIN-COVER-300x169.png","large":"https:\/\/marinersupdate.com\/blog\/wp-content\/uploads\/2026\/05\/CAPTAIN-COVER-1024x576.png"},"ams_acf":[],"_links":{"self":[{"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/posts\/527","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/comments?post=527"}],"version-history":[{"count":1,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/posts\/527\/revisions"}],"predecessor-version":[{"id":533,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/posts\/527\/revisions\/533"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/media\/528"}],"wp:attachment":[{"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/media?parent=527"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/categories?post=527"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/marinersupdate.com\/blog\/wp-json\/wp\/v2\/tags?post=527"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}