Ingalls Weather<p><strong>Noctilucent clouds on display above Vancouver this morning</strong></p><p>The nature of my job has me up pretty early most days. As I was getting ready for work this morning, I glanced outside around 4:30 and was pleased to see some noctilucent clouds in the early-dawn light. Venus was also shining brightly near the crescent moon.</p><p>Noctilucent clouds are a special treat for night sky watchers for a couple weeks on either side of the summer solstice. The further north one is, the longer the season is for them to be seen (until you get toward the Arctic). They can only be seen as far as about the 45th parallel but are more common between 50° and 70° north or south of the equator.</p><blockquote><p><em>Ingalls Weather thanks the support it gets from donors. Please consider making a small donation </em><a href="https://ingallswx.com/donate/" rel="nofollow noopener" target="_blank">at this link</a><em> to help me pay for the website and access to premium weather data.</em></p></blockquote><p>The Lower Mainland is just north of 49°N which is certainly high enough to enjoy noctilucent clouds in the summer. Calgary and Edmonton do a bit better, though, lying near 51°N and 53°N respectively.</p><p>This morning’s display was not particularly impressive. Summer 2021 brought much more coverage on the northern horizon as seen from Kennewick, Washington, where I was living at the time. Still, I was happy to see them for the first time in a couple years.</p> <p>Type your email…</p><p>Subscribe</p> Noctilucent clouds seen from Kennewick, Washington in June 2021.<p>Noctilucent clouds are the highest visible clouds in the Earth’s atmosphere. They form from ice particles in the mesosphere around 75 to 85 km (46 to 53 miles) above the surface. By contrast, the kinds of clouds we are more familiar with almost exclusively exist in the troposphere which extends from the surface up about 18 km (60,000 feet).</p><p>Noctilucent clouds are visible during astronomical twilight which begins about 45 minutes after sunset and ends about 45 minutes before sunrise. The length of astronomical twilight varies based on the date and the observer’s latitude.</p><p>They can be present during both the day and night but they are too thin to be seen in daytime and once the sun is 18° below the horizon they are no longer illuminated to be visible at night.</p><p>Clouds form as water or ice attach to microscopic particles in the atmosphere. This includes dust, pollution, pollen, and many other things. This high in the atmosphere it is believed that the ice that forms noctilucent clouds is attaching to dust from micrometeors entering the atmosphere and ash from major volcanic eruptions.</p><p>They were first described in 1885 just two years after the incredible eruption of Krakatoa in Indonesia. Some sources, including the Smithsonian Magazine, imply that the observation of these clouds in 1885 was related to that eruption.</p><p>Noctilucent clouds can form from rocket launch exhaust making them occasionally visible near launch sites in places like California and Florida. Evidence shows that their frequency and duration may be increasing from increased methane emissions related to human activity.</p><p>These clouds are also visible at similar latitudes in the Southern Hemisphere though they appear to be dimmer and interestingly form about 1 km (3,000 feet) higher than north of the equator. If human methane emissions play a role in their frequency it makes sense that they are less active in the Southern Hemisphere were there are fewer people.</p><p>The term <em>noctilucent</em> comes from combining two Latin terms that roughly translate to “night shining.” They are sometimes abbreviated as NLC.</p><p>Noctilucent cloud season is drawing to a close for the Lower Mainland and other Southern B.C. locations. I don’t know if they’ll be out again tonight or in the next couple days but the window for them being visible at this latitude will end soon.</p><p><a rel="nofollow noopener" class="hashtag u-tag u-category" href="https://ingallswx.com/tag/bcstorm/" target="_blank">#BCstorm</a> <a rel="nofollow noopener" class="hashtag u-tag u-category" href="https://ingallswx.com/tag/cloud/" target="_blank">#cloud</a> <a rel="nofollow noopener" class="hashtag u-tag u-category" href="https://ingallswx.com/tag/vancouver/" target="_blank">#Vancouver</a> <a rel="nofollow noopener" class="hashtag u-tag u-category" href="https://ingallswx.com/tag/weather/" target="_blank">#Weather</a> <a rel="nofollow noopener" class="hashtag u-tag u-category" href="https://ingallswx.com/tag/yvr/" target="_blank">#yvr</a></p>