Learn a new word every day. These smaller particles scatter light in a different way, which is what creates the distinctive luminescent appearance. Ice polar stratospheric clouds, or nacreous clouds, occur mainly at high latitudes during the winter when temperatures in the stratosphere fall below the frost point.

The text enclosed in grey-shaded boxes, like this example, comprises Annex I to the Technical Regulations (WMO-No.

The characteristic bright iridescent colours, resulting from diffraction and interference of light waves, suggest that the clouds are composed of similarly sized spherical crystals of about 10 μm in diameter.

These clouds appear mostly during winter in regions of high latitude. ©Cherie Ude, shown with permission. Later, with the Sun further below the horizon, the various colours are replaced by a general coloration that changes from orange to pink and contrasts vividly with the darkening sky. Please tell us where you read or heard it (including the quote, if possible).

Ice polar stratospheric clouds, also known as mother-of-pearl clouds. To save this word, you'll need to log in. Start your free trial today and get unlimited access to America's largest dictionary, with: “Nacreous cloud.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nacreous%20cloud. It is largely made up of ice crystals and despite its stunning appearance, nacreous cloud is a destructive cloud as it helps in destroying the ozone layer. Take a look at 7 fascinating things you might not know about one of the most extraordinary yet commonplace…, Stratus clouds tend to be featureless, low altitude clouds that cover the sky in a blanket of white or gre…, 'March winds and April showers bring forth May flowers'. Non-lenticular nacreous clouds may appear to move slowly, due to their distance from the observer, as they appear above the setting Sun. — called also

What made you want to look up nacreous cloud? Clouds resembling Cirrus or Altocumulus lenticularis and showing very marked irisation, similar to that of mother of pearl; the most brilliant colours are observed when the Sun is several degrees below the horizon.

Support your business with world-leading science and technology. nacreous cloud [ nā ′krē-əs ] A cloud resembling a cirrus, showing iridescent coloration when the Sun is several degrees below the horizon. If Cirrus and nacreous clouds coexist after sunset, the high altitude of the nacreous clouds causes them to show bright colours after the Cirrus has already turned grey.

Introduction and principles of cloud classification, Orographic influence on the windward side, Nitric acid and water polar stratospheric clouds, Noctilucent clouds (polar mesospheric clouds), Classification and symbols of meteors other than clouds, Definitions and descriptions of meteors other than clouds, Observation of meteors other than clouds from the Earth's surface, Observation of hydrometeors other than clouds, Observation of clouds from the earth's surface, Observation of clouds from mountain stations, Code specifications and coding procedures, Coding instructions of clouds in the codes C, Issues for observation of clouds from aircraft, Descriptions of clouds as observed from aircraft, Appendix 1 - Etymology of latin names of clouds, Appendix 2 - Historical bibliography of cloud classification, Appendix 3 - History of cloud nomenclature, Appendix 4 - Lists of tables, figures and acronyms, Foreword to the 1987 edition of volume II. Nacreous clouds are rare and very high clouds, known mainly for the coloured light they reflect after sunset and before sunrise. After sunset, they are characterized by brilliant iridescent colours, which are more extensive and more intense than the localized irisation, or iridescence, that often appears on the edges of thin tropospheric clouds (for example, Altocumulus lenticularis). Nacreous cloud definition is - a luminous iridescent cloud that occurs at altitudes of about 85,000 feet —called also mother-of-pearl cloud. You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary. Ice polar stratospheric clouds (nacreous clouds) form at temperatures below the ice frost point, typically near −85 °C, which is colder than the average lower stratosphere temperature.

Their formation may also be associated with severe tropospheric storms.

Can you spell these 10 commonly misspelled words? Iridescence is most brilliant when the Sun is several degrees below the horizon. The clouds are illuminated from below and often glow in vivid colours. Nacreous clouds form in the lower stratosphere over polar regions when the Sun is just below the horizon. The colours are reminiscent of the colours which reflect from a thin layer of oil on top of water, an effect known as iridescence. Nacreous clouds are rare and very high clouds, known mainly for the coloured light they reflect after sunset and before sunrise. By day, nacreous clouds often resemble pale Cirrus. Who we are, what we do and organisational news. The ice particles that form nacreous clouds are much smaller than those that form more common clouds. For this reason, they are sometimes known as polar stratospheric clouds. Test Your Knowledge - and learn some interesting things along the way. These smaller particles scatter light in a different way, which is what creates the distinctive luminescent appearance. Nacreous clouds (Type II PSCs) glow brightly with vivid iridescent colours.

Their formation may also be associated with severe tropospheric storms. Because they form in a polar vortex, they are associated mostly with very cold and dry weather. Everything you need to know about the forecast, and making the most of the weather. Due to their high altitude and the curvature of the Earth’s surface, these clouds are lit up by sunlight from below the horizon and reflect it to the ground, shining brightly well before dawn and after dusk.


They are most likely to be viewed when the Sun is between 1º and 6º below the horizon and in places with higher latitudes, such as Scandinavia and northern Canada. When a few letters make a large difference.

This is the reason why this cloud is named as the mother of pearl clouds. On rare occasions, they have been reported in other parts of northern Europe.

Accessed 2 Oct. 2020. The ice particles that form nacreous clouds are much smaller than those that form more common clouds. Nacreous clouds are often lenticular wave clouds and thus are found downwind of mountain ranges that induce gravity waves in the stratosphere. Nacreous clouds that are also lenticular will be stationary at the crest of a gravity wave, although the air flows through the cloud.
By day, nacreous clouds often resemble pale Cirrus. They are most common in Antarctica, but have also been observed in the Arctic, Scotland, Scandinavia, Alaska, Canada and the northern Russian Federation. The latest breakthroughs, research and news from the Met Office. Post the Definition of nacreous cloud to Facebook, Share the Definition of nacreous cloud on Twitter, 9 Pairs of Words That Look the Same But Different, More than 250,000 words that aren't in our free dictionary, Expanded definitions, etymologies, and usage notes. Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! Nacreous clouds form in the lower stratosphere over polar regions when the Sun is just below the horizon. Nacreous clouds are often lenticular wave clouds and thus are found downwind of mountain ranges that induce gravity waves in the stratosphere. Nacreous clouds only form below -78 °C so are most likely to occur during the polar winter. Nacreous clouds form in the lower stratosphere over polar regions when the Sun is just below the horizon. They are wave clouds and their undulating sheet-like forms reveal the winds and waves of the stratosphere.

What weather is associated with Nacreous clouds? Nacreous clouds are classified into three types, Ia, Ib and II, according to their chemical composition, height and ambient temperature.

Delivered to your inbox! Nacreous clouds are polar stratospheric clouds that have shiny, beautiful colors similar to those found in a seashell.

Because of the very low temperatures required, nacreous clouds are usually only visible from the UK when the cold air which circulates around polar regions in the stratosphere (known as the stratospheric polar vortex) is displaced and hovers temporarily over the UK.

mother-of-pearl cloud. Verification, impacts and post-processing, Climate information for international development, Science for Impacts, Resilience and Adaptation (SIRA), Atmospheric processes and parametrizations, Regional model evaluation and development, Environmental Hazard and Resilience Services, National Meteorological Library & Archive. Shape: large thin discs, often reflecting vivid colours, Latin: no direct Latin translation, but the old English word “Nacre” means “mother of Pearl”. 49) and has the legal status of standard practices and procedures.