10 Phenomenon of Natural Wonders (Subhanallah)
Sebuah fenomena alam yang terjadi karena berkumpulnya mikroorganisme di pesisir tempat bergabungnya air dari muara, laut atau air sungai dan membuat air menjadi berwarna ungu dan merah.
Red Tides merupakan sebuah fenomena alam air laut yang berubah warna menjadi merah yang disebabkan oleh fitoplankton. Red Tides dapat menyebabkan kematian massal biota laut, perubahan struktur komunitas ekosistem perairan, keracunan dan juga bisa menyebabkan kematian pada manusia. Ini terjadi dikarenakan fitoplankton tersebut mengeluarkan racun.
Faktor yang mempengaruhi fenomena Red Tides yaitu termasuk suhu permukaan laut yang hangat, salinitas rendah, kandungan gizi yang tinggi, dan laut yang tenang. Selain itu, fitoplankton tersebut dapat menyebar dengan jauh oleh angin, arus, dan badai.
What is Red Tide?
Red tide is a phenomenon caused by algal blooms (Wikipedia definition) during which algae become so numerous that they discolor coastal waters (hence the name “red tide”). The algal bloom may also deplete oxygen in the waters and/or release toxins that may cause illness in humans and other animals. Species in the United States that release these harmful toxins include:
* Alexandrium fundyense—found along the Atlantic coast from the Canadian Maritimes to southern New England
* Alexandrium catenella—found along the Pacific coast from California to Alaska
* Karenia brevis—found in the Gulf of Mexico along the west coast of Florida
What Causes Red Tide?
Major factors influencing red tide events include warm ocean surface temperatures, low salinity, high nutrient content, calm seas, and rain followed by sunny days during the summer months. In addition, algae related to red tide can spread or be carried long distances by winds, currents, storms, or ships.
Where Are Red Tides Found?
Red tide is a global phenomenon. However, since the 1980s harmful red tide events have become more frequent and widespread. Detection of a spread is thought to be influenced by higher awareness of red tide, better equipment for detecting and analyzing red tide, and nutrient loading from farming and industrial runoff. Countries affected by red tide events include: Argentina, Australia, Brazil, Canada, Chile, Denmark, England, France, Guatemala, Hong Kong, India, Ireland, Italy, Japan, the Netherlands, New Zealand, Norway, New Guinea, Peru, the Philippines, Romania, Russia, Scotland, Spain, Sweden, Thailand, the United States, and Venezuela.
How Are Red Tides Harmful?
Red tide algae make potent natural toxins. It is unknown why these toxins are created, but some can be hazardous to larger organisms throught the processes of biomagnification and bioaccumulation. Grazers such as fish and krill are unaffected by the toxins, so as they eat the algae the toxins are concentrated and accumulate to a level that is poisonous eat to organisms that feed on them. Large fish kills and several mammalian diseases and deaths have been attributed to consumption of shellfish during red tide algal blooms. Diseases that may affect humans include:
* Paralytic Shellfish Poisoning (PSP)—This disease is caused by the production of saxitoxin by the Alexandrium species. It is common along the Atlantic and Pacific coasts in the US and Canada. Poisoning occurs when one ingests shellfish contaminated with PSP toxins causing disruption of nerve function and paralysis. Extreme cases may result in death by asphyxiation by respiratory paralysis.
* Diarrhetic Shellfish Poisoning (DSP)—This disease is caused by the Dinophysis species. It generally occurs in Japan and Europe, but it has also been found in other countries such as Canada, the US, Chile, New Zealand, and Thailand. Symptoms of DSP include diarrhea, nausea, vomiting, abdominal pain, and cramps. DSP is generally not lethal.
* Amnesic Shellfish Poisoning (ASP)—This disease, which has been found along the eastern Canadian coast, is caused by domoic acid producing planktonic and benthic algae, including Pseudo-nitzschia pungens forma. Pseudo-nitzschia multiseries and Amphora coffaeformis. It can also be found in soft shell clams and blue mussels infected by Pseudo-nitzschia delicatissima. Gastric and neurological symptoms include dizziness, disorientation and memory loss.
What is Being Done About Red Tide?
Technological advancements such as satellite imagery have allowed scientists to better track and monitor harmful algal blooms. Tracking and monitoring red tide algae helps reduce harmful effects of the algae by providing warnings against eating infected shellfish and against swimming in infected waters. For example, the Sarasota Operations Coastal Oceans Observation Lab (SO COOL) has developed instruments that can test for red tide algae in coastal waters. Finally, researchers are attempting to develop an antidote to the red tide toxins. Interestingly, while developing such anti-toxins, researchers have found a possible cystic fibrosis treatment.
Light pillar terlihat seperti tiang penyanggah langit yang bersinar keatas tanpa asal yang jelas. Fenomena ini terlihat saat cahaya dipantulkan oleh kristal es baik dari bawah maupun dari atas.Fenomena visual yg tercipta krn pantulan cahaya dari kristal es dekat permukaan planar sejajar horisontal. Cahaya dapat berasal dari matahari, biasanya pada saat matahari mau terbenam, dalam hal ini fenomena ini disebut pilar matahari. Dapat juga datang dari bulan atau dari sumber-sumber terestrial seperti lampu jalan.
Light Pillars penuh warna sering muncul di musim dingin saat salju atau es kristal memantulkan cahaya dari sumber yang kuat seperti matahari atau bulan. Dibantu oleh suhu yg dingin, pilar cahaya muncul ketika cahaya memantul dari permukaan datar mengambang kristal es yang relatif dekat dengan tanah. Pilar tampak seperti bulu cahaya yang memperpanjang secara vertikal di atas atau di bawah sumber cahaya, atau keduanya.pilar cahaya juga di bentuk dari sumber cahaya buatan seperti lampu jalanan, lampu mobil atau sumber cahaya yang kuat dari arena ice skating seperti pada gambar di atas dari Fairbanks, Alaska. Meskipun mereka merupakan fenomena lokal, pilar cahaya dapat melihat jauh seperti sebuah aurora. Semakin dekat seseorang melihat sumber pilar cahaya, semakin besar tampaknya.
A light pillar can sometimes be seen above the sun when it is setting or rising. It is caused by reflection of light off the base of horizontally aligned plate ice crystals in the atmosphere. The extend of the pillar is usually only a few degrees. More rarely, it is as much as 20 degrees or more. Light pillars are possible above and below the sun or moon; however, for earth-bound observers, the upper light pillar is most common, while the lower pillar is more likely when you are in an airplane flying above a cloud of ice crystals. The upper and lower light pillars at the sun can be present together with the parhelic circle and then form a giant cross in the sky, which was considered an omen in ancient and medieval folklore.
Light pillars are a kind of optical phenomenon which is formed by the reflection of sunlight or moonlight by ice crystals that are present in the Earth’s atmosphere. Owing to such optical phenomenon the sky sometimes seems like a natural kaleidoscope. Though light pillars seem like weather illusion , they are natural phenomena.
The light pillar looks like thin columns that that are sometimes extend vertically below or above the source of light. The Light Pillars are prominently visible when the sun is low or lies below the horizon. Normally these Light Pillars form arcs that extend from five to ten degrees just beyond the solar disc. Sometimes similar reflection of moonlight by varied forms of ice crystals may also take place thus resulting in the form of light pillars. Light Pillars are particularly formed due to the reflection of column or flat shaped ice crystals that are present in the ice or cirrus clouds, hence the name light pillars.
Colourful light pillars often appear in winter when snow or ice crystals reflect light from a strong source like the sun or moon. Aided by extreme cold, light pillars appear when light bounces off the surface of flat ice crystals floating relatively close to the ground. The pillars look like feathers of light that extend vertically either above or below the light source, or both. Light pillars also form from strong artificial light sources like street lamps, car headlights or the strong light sources of an ice-skating rink as in the picture above of Fairbanks, Alaska. Though they are local phenomena, light pillars can look distant like an aurora. The closer an observer is to the source of the light pillar, the larger it seems.
Moeraki Boulders sepanjang hampir sempurna batu dengan keliling hingga 4meters. Mereka berada di Pulau Selatan Selandia Baru Selandia Baru dekat kota Moeraki, sekitar 35 km sebelah selatan Oamaru Oamaru. Moeraki Boulders muncul di dasar laut sekitar 60 juta tahun yang lalu oleh lapisan bertahap dari garam kalsium sekitar inti keras. Ini batu abu-abu yang tersebar di hampir 50 meter bagian panjang. Menurut legenda Moeraki Boulders Maori adalah makanan keranjang dari perahu Araiteura, yang rusak, dan keranjang berubah menjadi batu halus.
The Boulders Moeraki adalah bola batu yang menakjubkan dan mereka mengingatkan saya banyak di lingkungan orang-orang misterius yang dapat ditemukan di Amerika Selatan atau beberapa negara Eropa.Berbeda dengan bola misterius dari Amerika Selatan yang arkeolog tidak memiliki penjelasan yang masuk akal, yaitu sesuatu yang berbeda. Mereka terbentuk batu-batu bulat di sedimen dasar laut dalam proses yang mirip dengan proses penciptaan mutiara. Mereka telah membentuk bola selama ribuan tahun dan itu adalah luar biasa bagaimana bentuknya hampir sempurna seperti mereka yang dibuat oleh manusia bukan oleh alam. Beberapa dari mereka cukup besar dan sekitar 3 meter dengan diameter. Mereka dapat ditemukan batu-batu besar di Pantai Koekohe di Selandia Baru.
Scattered along the beach at Moeraki which is some 40 kilometers south of Oamaru, the boulders are a popular visitor attraction. The soft mudstone containing the boulders was raised from the sea bed around 15 million years ago and sea erosion of the cliff is exposing the erosion-resistant boulders. Emerging from the cliff, as if being born from the earth, the World famous Moeraki Boulders are septerian concretions formed some 65 million years ago. Crystallization of calcium and carbonates around charged particles in muddy undersea sediments gradually formed the boulders in a process taking as long as four million years. The soft mudstone containing the boulders was raised from the sea bed around 15 million years ago and sea erosion is exposing the erosion-resistant boulders. According to Maori tradition, the boulders are gourds and calabashes, which is traditional maori food, washed from the great voyaging canoe Araiteuru when it was wrecked upon landfall in New Zealand some 1000 years ago. Almost Unique in the world, the Moeraki Boulders are situated about 25 mins south from Oamaru along Sh1.Tthey can be seen emerging from the cliffs and slowly disappearing into the sand and the sea.Visitors can walk along the beach to visit the boulders, best seen at low tides, but visible most of the time.
The Moeraki Boulders are a number of huge spherical stones, found strewn along a stretch of Koekohe Beach near Moeraki, a small settlement just south of Hampden on New Zealand’s Otago coast. These boulders are grey-coloured septarian concretions which have been exposed through shoreline erosion from black mudstone coastal cliffs that back the beach. They originally formed in ancient sea floor sediments during the early Paleocene some 60 million years ago. The boulders weigh several tons and are up to three metres in diameter. Maori legend tells that the boulders are remains of calabashes, kumaras and eel baskets that washed ashore after the legendary canoe, the Araiteuru was wrecked at nearby Shag Point (Matakaea). In 1848 W.B.D. Mantell sketched the beach and its boulders, more numerous then than now.
Seperti halnya crop circle, ice circle merupakan fenomena aneh yang menyebabkan terbentuknya pola lingkaran aneh di permukaan air. Ice circle bisa terjadi dimana saja, jadi jika anda melihat pola lingkaran dipermukaan sungai atau danau, mungkin saja itu adalah ice circle yang baru terbentuk. Ice Circle atau lingkaran es adalah sebuah fenomena yang muncul pada air yang memiliki arus lambat di iklim dingin. Bentuknya menyerupai piringan raksasa yang terdiri dari es dan berotasi secara lambat di permukaan air. Misteri ini sesungguhnya sudah pernah disinggung pada abad ke-19. Sebuah gambar ilustrasi dari Ice Circle pernah dipublikasikan di majalah Scientific American pada tahun 1895. London News juga pernah melaporkan fenomena ini yang terjadi di Toronto tahun 1930.
Ice Circle umumnya muncul pada kelokan sungai dimana arus air yang berakselerasi menciptakan sebuah kekuatan yang disebut “rotational shear“, yang kemudian mematahkan bongkahan es dan memutarnya. Sejalan dengan perputaran piringan itu, ia menggiling es di sekelilingnya sehingga menjadi halus dan membentuk lingkaran sempurna. Fenomena ini walaupun sudah teridentifikasi penyebabnya, namun tetap merupakan kejadian yang langka.
Fenomena unik ini sering terlihat didaerah uk. Roy Jefferies, ketika sedang membawa anjingnya jalan di pinggiran sungai dia melihat terbentuknya pola lingkaran unik ini. Menurut dia diameter ice circle ini sekitar 10 kaki.
Ice circles are similar to crop circles only etched in thin ice on ponds and rivers rather than fields. Generally measuring between 15 to 20 feet in diameter, these ice circles have appeared in thin ice ponds, and water courses, in Canada and the US for many years.
An unusual rotating ice circle, normally found in the cooler rivers of Scandinavia or North America, has formed in the UK waterways.
The cause of the rare phenomenon is unclear, with very little scientific evidence available to explain the formation of the discs. UFO-enthusiasts claim that, like crop circles, the perfect discs are created by visiting aliens, but scientists believe the extreme cold weather combined with an unusual current is the more likely reason.
Formasi bebatuan yg terbentuk dikarenakan lava dari letusan gunung yg mendingin. karena magma mendingin dengan cepat, sehingga sebagian kecilnya membentuk kristal. Basalt yg terkenal di dunia terletak di Giant’s Causeway di Irlandia Utara.
Columnar Basalts are rock formations resulting from the quick cooling of lava flow. Fractures form in a random cellular network (similar to soap bubbles, organic cells, etc.), though the average distribution of sides is six, giving the hexagonal structures an eerie man-made appearance.
Giant lava flows covered much of Eastern Washington and parts of Idaho and Oregon 17 to 12 million years ago. Unlike volcanic eruptions such as Mt. St. Helens, lava erupted out of cracks in the earth’s crust and flowed for long distances. This type of volcano is called a basalt flood. It is estimated that around 300 floods occurred on the Columbia Plateau. The basalt cooled from the top of the lava flow, and also from the bottom up. As the basalt cooled it shrunk 5 to 10 percent and cracked, forming columns. As the basalt crystallized the cracks grew, but the bottom cracks did not match those at the top and created an area between the cooling layers that is chaotic compared to the uniform top and bottom layers. The in-between layer is called the entablature. The long columns that are obvious in the photo to the left is the lower portion of a basalt flow; the upper columns of this flow have been subjected to significant erosion, and only the entablature between the layers remains.
The shape, formation and texture of a basalt is usually determined by the way it erupted and also where it erupted in terms of if it erupted in the sea, in an volatile cinder eruption or as creeping pahoehoe lava flows, the standard image of Hawaiian basalt eruptions. The Columnar Basalt is produced during the period of the cooling of the thick lava flow, which forms contractional joints or fractures. The flow usually shrinks in the vertical measurement without fracturing, and cannot manage to sink in horizontal direction until the cracks are formed.
basalt (bəsôlt`, băs`ôlt), fine-grained rock, of volcanic origin, dark gray, dark green, brown, reddish, or black in color. Basalt is an igneous rock, i.e., one that has congealed from a molten state. Basaltic magma is derived by partial melting of the peridotite that is found in the asthenosphere which reaches the mid-ocean ridges, such as the Mid-Atlantic Ridge, and forms the new oceanic crust, the uppermost layer of the lithosphere. Because molten basalt is lighter than peridotite, it rises more rapidly. Basaltic magmas contain around 50% silica; they are the most common extrusive rocks and comprise more than 90% of all volcanic rock. It forms mostly lava flows, including present-day Hawaiian flows, and the ancient Columbia River plateau of the NW United States. Basalt dominates the mid-ocean islands and surrounding regions of the Hawaiian Islands and Iceland, as found by samples of lava flows found in drill cores recovered by vessels of the Deep Sea Drilling Project and the now defunct Project Mohole. Basalt contains a high percentage of iron and magnesium. Some basalts are porphyritic, i.e., they contain large crystalline structures called phenocrysts embedded in a matrix called a groundmass (see porphyry). Phenocrysts are usually formed in the molten lava before eruption and are often composed of the minerals olivine
and pyroxene. Where molten basalt cools rapidly, as at the earth’s surface, fine-grained rocks are formed. Basalt may be compact or vesicular, i.e., porous because of gas bubbles contained in the lava while it is solidifying. If the vesicles become subsequently filled with secondary minerals, e.g., quartz or calcite, the rock is called amygdaloidal basalt. Basalt may form as columns of rock, such as the Devil’s Tower in Wyoming; or it may form as twisted coils of rope, or cinders of jagged rock, called “pahoehoe” and “aa,” respectively. Gabbros are similar in composition to basalt, but gabbros are coarse-grained rocks formed by slow cooling in large underground masses, common in New York’s Adirondack Mts. When subjected to metamorphism, i.e., high temperatures and great pressures, basalt is transformed into various kinds of schists including hornblende schist. Fine and coarse-grained crystalline rocks returned from various regions of the moon by Apollo astronauts were similar in many respects to terrestrial basalts. Fine-grained basaltic lunar rocks are vesicular, with glass-lined pits on exposed surfaces that have been interpreted as micrometeorite impact scars. Lunar rocks differed from terrestrial basalts in lacking water and organic compounds, and were higher in titanium, magnesium, and iron.
Catatumbo Lightning adalah sebuah fenomena aneh yang terjadi pada atmosfer bumi. Catatumbo Lightning adalah fenomena petir yang terus menyambar dengan intensitas yang tinggi. Bahkan bisa mencapai 400.000 lebih sambaran dalam setahun. Fenomena ini terdapat di negara Venezuela.
Setelah berabad – abad Catatumbo Lightning terus menerus muncul, pada Januari 2010 Catatumbo Lightning sempat tidak muncul. Banyak yang menyangka jika Catatumbo Lightning sudah tidak akan muncul – muncul kembali. Dan hingga pada April 2010, Catatumbo Lightning muncul kembali. Belakangan diketahui bahwa kekeringan lah yang menyebabkan Catatumbo Lightning sempat tidak muncul – muncul.
Catatumbo Lightning terletak di muara sungai Catatumbo, lebih tepatnya di Danau Maracaibo, Venezuela. Petir yang menyambar pun intensitasnya cukup membuat saya sempat menggelengkan kepala. Bayangkan saja, petir tersebut rata – rata menyambar selama 10 jam dalam sehari, dan dalam satu jam, petir tersebut dapat menyambar rata – rata sampai 280 kali sambaran dalam satu jam. Bisa anda bayangkan berapa kali petir Catatumbo menyambar dalam sehari !!
Dan yang lebih menakjubkannya lagi, dalam satu tahun, petir bisa menyambar sampai 140 sampai 160 hari dari 365 hari dalam setahun. Dan petir tersebut rata – rata menyambar dengan ketinggian 5 km. Sungguh luar biasa sekali bukan ?
Penelitian juga mengatakan bahwa Catatumbo Lightning adalah penghasil ozon dengan presentase tertinggi di dunia, dari seluruh tempat di dunia. Karena Catatumbo Lightning dapat menghasilkan sekitar 1.176.000 kW listrik di atmosfer.
Masyarakat kuno Yukpa di negeri tersebut mempercayai bahwa kilatan warna biru, putih, dan merah muda Catatumbo Lightning, terjadi saat kunang – kunang bertemu dengan roh para leluhur. Selama berabad – anad para pelaut pun menggunakan Catatumbo Lightning sebagai alat navigasi dari alam agar mereka tidak tersesat di lautan. Karena Catatumbo Lightning bisa terlihat dari jarak yang jauh, bahkan sampai ratusan mil jauh nya. Oleh karena itu Catatumbo Lightning juga sering disebut Lighthouse of Maracaibo atau dalam bahasa Indonesia nya Mercusuar Maracaibo.
Catatumbo Lightning konon telah ada sejak berabad – abad yang lalu. Catatan sejarah mengenai Catatumbo Lightning sendiri pertama kali tercatat pada tahun 1597 dalam sebuah puisi epik karangan Lope de Vega berjudul La Dragontea.
Alexander von Humboldt, seorang naturalis Prussia, pernah menggambarkan Catatumbo Lightning sebagai “ledakan listrik yang seperti sinar pendar”. Seorang Geografis dari Italia yang bernama Agustin Codazzi, pernah menggambarkan Catatumbo Lightning sebagai “kilat yang tampaknya muncul dari sungai Zulia lanjutan dan sekitarnya”.
Studi mengenai Catatumbo Lightning pertama kali dilakukan oleh Melchor Centeno. Kemudian pada tahun 1966 sampai 1970, ilmuwan Andrew Zavrostky melakukan tiga ekspedisi dengan bantuan dari University of Los Andes yang menyimpulkan bahwa areal tersebut akan memiliki episentris di rawa – rawa dari Swamp National Park Juan Manuel de Aguas, Claras Aguas Negras dan Danau Maracaibo bagian barat. Pada tahun 1991, ia juga mengatakan bahwa fenomena tersebut terjadi karena adanya pertemuan arus udara hangat dan dingin di daerah tersebut. Penelitian tersebut juga mengatakan bahwa penyebab untuk kilat terisolasi mungkin karena keberadaan uranium di dasar bebatuan.
Kemudian pada tahun 1997 sampai 2000, Nelson Falcon melakukan beberapa ekspedisi dan menghasilkan model mikrofisika dari Catatumbo Lightning yang mengidentifikasikan bahwa metana lah yang menyebabkan Catatumbo Lightning. Namun saat itu teori ini masih dianggap hanya sekedar spekulasi.
Tapi belakangan, penyebab fenomena tersebut adalah gas nontoksik metana yang menguap dari rawa dan endapan minyak.
The Catatumbo Lightning (Spanish Relámpago del Catatumbo) is an atmospheric phenomenon in Venezuela. It occurs strictly in an area located over the mouth of the Catatumbo River where it empties into Lake Maracaibo. The frequent, powerful flashes of lightning over this relatively small area are considered to be the world’s largest single generator of tropospheric ozone but not replenishing the ozone layer, as the latter is located in the stratosphere.
It originates from a mass of storm clouds that create a voltaic arc at more than 5 km of height, during 140 to 160 nights a year, 10 hours per day and up to 280 times per hour. It occurs over and around Lake Maracaibo, typically over a bog area that forms where the Catatumbo River flows into the Venezuelan lake.
After appearing continually for centuries, the lightning was not seen for several months between January and April 2010, apparently due to a drought, raising fears that it may have been extinguished permanently.
The Catatumbo lightning usually develops between the coordinates 8 ° 30 ‘and 9 º 45’ north latitude and 71 º and 73 º W.
The storms (and associated lightning) are likely the result of the winds blowing across the Maracaibo Lake and surrounding swampy plains. These air masses inevitably meet the high mountain ridges of the Andes, the Perijá Mountains (3,750m), and Mérida’s Cordillera, enclosing the plain from three sides. The heat and moisture collected across the plains creates electrical charges and, as the air masses are destabilized at the mountaiN ridges, resulting in almost continual thunderstorm activity.
The phenomenon is characterized by almost continuous lightning, mostly within the clouds, which is produced in a large vertical development of clouds that form large electric arcs between 2 and 10 km in height (or more). The lightning tends to start approximately one hour after dusk.
Among the major modern studies there is the one done by Melchor Centeno, who attributes the origin of the thunderstorms to closed wind circulation in the region.
Between 1966 and 1970 the scientist Andrew Zavrostky with assistance from the University of Los Andes made three expeditions which concluded that the area would have several epicentres in the marshes of the Swamp National Park Juan Manuel de Aguas, Claras Aguas Negras and west Lake Maracaibo, and in 1991 he suggested that the phenomenon occurred due to cold and warm air currents meeting around the area. The study also speculated that an isolated cause for the lightning might be the presence of uranium in the bedrock.
Between 1997 and 2000 Nelson Falcón conducted several expeditions and produced the first microphysics model of the Catatumbo Lightning identifying the methane produced by the swamps and the oil deposits in the area as a major cause of the phenomenon. It has been noted to have little effects on local flora such as ferns, despite concerns.
Historically the first written mention of the Catatumbo lightning was in the epic poem “La Dragontea” by Lope de Vega (1597) where the defeat of the English pirate or privateer Sir Francis Drake is narrated. The Prussian naturalist and explorer Alexander von Humboldt once described it as “electrical explosions that are like phosphorescent gleam”. Italian geographer Agustin Codazzi described it as a “lightning that seems to arise from the continued Zulia river and its surroundings”. The phenomenon became so celebrated that it was depicted in the flag and coat of arms of the state of Zulia, which contains Lake Maracaibo, and mentioned in the state’s anthem. This phenomenon, for century popularly known as the Lighthouse of Maracaibo since its lights are visible for miles out at sea and the boats that sail the area navigate at night without any problems, e.g. from the lake (where no clouds usually occur at night).
Cueva de los Cristales (Cave of the Crystals) atau gua kristal, adalah sebuah gua yang terdapat di daerah Naica Mine, Chihuahua, Meksiko. Gua tersebut mengandung kristal selenit raksasa, dan beberapa merupakan kristal alami terbesar di dunia.
Kristal terbesar berukuran 11 m (36 feet), diameter 4 m (13 feet) dan beratnya 55 ton. Ukuran guanya sendiri sekitar 30 m panjangnya, lebar 10 m dan berada di kedalaman 300 m di bawah tanah. Gua ini ditemukan pada tahun 2000 oleh para penambang yang menggali terowongan baru bagi perusahaan pertambangan Industrias Peñoles yang terletak di Naica, Meksiko.
Suhu dalam gua panas, 43 °C (109 °F) dengan kelembabpan 90-100%. Suhu yang panas ini dikarenakan posisi gua yang dekat dengan saluran magma. Gua ini sendiri relatif tidak dapat dikunjungi, karena tanpa peralatan khusus, manusia hanya bisa hidup 10 menit di kondisi ini dan 45 menit dengan menggunakan peralatan khusus. Selain suhu, bahaya yang mengancam adalah apabila kita salah jatuh dan terpeleset maka bisa saja tertusuk oleh kristal yang tajam dan mati.
Kristal gua terbentuk karena ada dapur magma bawah tanah di bawah gua. Magma yang memanaskan air tanah dan menjadi jenuh dengan mineral, termasuk sejumlah besar gips. Ruang rongga gua itu diisi dengan air panas mineral yang kaya dan tetap penuh selama sekitar 500.000 tahun. Selama waktu ini, suhu air tetap sangat stabil di atas 50 ° C. Hal ini memungkinkan kristal mikroskopis untuk terbentuk dan tumbuh. Mereka terus tumbuh sampai ukuran besar.
Cave of the Crystals or Giant Crystal Cave (Spanish: Cueva de los Cristales) is a cave connected to the Naica Mine 300 metres (980 ft) below the surface in Naica, Chihuahua, Mexico. The main chamber contains giant selenite crystals, some of the largest natural crystals ever found. The cave’s largest crystal found to date is 11 m (36 ft) in length, 4 m (13 ft) in diameter and 55 tons in weight. The cave is extremely hot with air temperatures reaching up to 58 °C (136 °F). The cave is relatively unexplored due to the extreme temperatures and high humidity. Without proper protection people can only endure approximately ten minutes of exposure at a time. A group of scientists known as the Naica Project have been heavily involved in researching these caverns.
Naica lies on an ancient fault and there is an underground magma chamber below the cave. The magma heated the ground water and it became saturated with minerals, including large quantities of gypsum. The hollow space of the cave was filled with this mineral rich hot water and remained filled for about 500,000 years. During this time, the temperature of the water remained very stable at over 50°C. This allowed crystals to form and grow to immense sizes.
In 1910 miners discovered a cavern beneath the Naica mine workings, the Cave of Swords (Spanish: Cueva de las Espadas). It is located at a depth of 120 m, above the Cave of Crystals, and contains spectacular, smaller (1 m long) crystals. It is speculated that at this level, transition temperatures may have fallen much more rapidly, leading to an end in the growth of the crystals.
The Giant Crystal cave was discovered in 2000 by miners excavating a new tunnel for the Industrias Peñoles mining company located in Naica, Mexico, while drilling through the Naica fault, which they were concerned would flood the mine. The mining complex in Naica contains substantial deposits of silver, zinc, and lead.
The Cave of Crystals is a horseshoe-shaped cavity in limestone rock. Its floor is covered with perfectly-faceted crystalline blocks. Huge crystal beams jut out from both the blocks and the floor. The caves are accessible today because the mining company’s pumping operations keep them clear of water. If the pumping were stopped, the caves would again be submerged. The crystals deteriorate in air, so the Naica Project is attempting to visually document the crystals before they deteriorate further.
A further chamber was found in a drilling project in 2009. The new cave, named the Ice Palace, is 150 m deep and is not flooded, but its crystal formations are much smaller, with small ‘cauliflower’ formations and fine, threadlike crystals.
Crystals thrived in the cave’s extremely rare and stable natural environment. Temperatures hovered consistently around a steamy 136 degrees Fahrenheit (58 degrees Celsius), and the cave was filled with mineral-rich water that drove the crystals’ growth. Modern-day mining operations exposed the natural wonder by pumping water out of the 30-by-90-foot (10-by-30-meter) cave, which was found in 2000 near the town of Delicias (Chihuahua state map). Now García-Ruiz is advising the mining company to preserve the caves.
Penitentes, atau penitentes Nieves (“salju penitente berbentuk”, dalam bahasa Spanyol), adalah pembentukan salju yang ditemukan di ketinggian. Mereka mengambil bentuk bilah tipis tinggi salju mengeras atau es berjarak dekat dengan pisau berorientasi pada arah umum dari matahari. Pinakel salju ini atau es tumbuh diatas semua area yang tercakup glaciated dan salju di Andes Kering di atas 4.000 m (Lliboutry 1954a, 1954b Lliboutry, Lliboutry 1965). Mereka berbagai ukuran dari beberapa cm hingga lebih dari lima meter. (Lliboutry 1965, Naruse dan Leiva 1997). Louis Lliboutry (Spanyol: Luis Lliboutry) adalah seorang glaciologist Perancis-Chili awal, geografi dan pendaki gunung Andes. Salah satu karyanya yang paling terkenal adalah perjanjian luas Nieves y Glaciares de Chile: Fundamentos de glaciología diterbitkan pada tahun 1956. Lliboutry-karya terkonsentrasi ke glasiologi dari Andes Kering dan Basah Andes, khususnya di sekitar Santiago. Salah satu kontribusinya paling menonjol adalah tentang pembentukan penitentes.
Lliboutry mencatat bahwa kondisi iklim kunci untuk ablasi diferensial yang mengarah pada pembentukan penitentes adalah titik embun selalu di bawah titik beku.Dengan demikian, salju akan menghaluskan, karena sublimasi memerlukan masukan energi yang lebih tinggi daripada mencair. Setelah proses dimulai ablasi diferensial, geometri permukaan penitente berkembang menghasilkan suatu mekanisme umpan balik positif, dan radiasi yang terperangkap oleh beberapa refleksi antara dinding. Cekungan menjadi hampir setiap benda hitam untuk radiasi, sementara angin menurun mengarah ke udara kejenuhan, peningkatan suhu titik embun dan awal mencair. Dalam puncak cara, di mana massa yang hilang hanya karena sublimasi, akan tetap, serta dinding yang curam, yang hanya mencegat minimal radiasi matahari. Dalam ablasi palung ditingkatkan, mengarah ke pertumbuhan ke bawah penitentes. Sebuah model matematis dari proses tersebut telah dikembangkan oleh Betterton (2001), meskipun proses fisik pada tahap awal pertumbuhan penitente, dari butiran salju micropenitentes, masih tetap tidak jelas. Pengaruh penitentes terhadap keseimbangan energi permukaan salju, dan karena itu efeknya pada salju mencair dan sumber daya air telah dijelaskan oleh Corripio (2003) dan Corripio dan Purves (2005). Penitentes pertama kali diuraikan dalam literatur oleh Darwin pada tahun 1839. Pada tanggal 22 Maret 1835, ia harus menekan jalan melalui salju tercakup dalam penitentes dekat Pass Piuquenes, dalam perjalanan dari Santiago de Chile ke kota Mendoza Argentina, dan melaporkan kepercayaan lokal (terus hari ini) bahwa mereka dibentuk oleh angin kuat dari Andes.
Mekanisme ‘kelahiran mereka (The Penitentes)’ agak sedikit rumit, dan hal itu bergantung pada ablasi diferensial. Pada dasarnya, untuk penitentes untuk membentuk, titik embun harus di bawah titik beku. Akibatnya, salju akan menghaluskan, yang membutuhkan energi lebih dari mencair. Geometri dari permukaan menyediakan mekanisme umpan balik positif bagi radiasi, yang terjebak oleh beberapa refleksi, membuat cekungan. Cekungan ini, dikombinasikan dengan angin yang meningkatkan suhu titik embun menyediakan kondisi yang tepat untuk sublimasi untuk menciptakan dinding curam dan puncak.
Penitentes, or nieves penitentes (“penitente-shaped snows”, in Spanish), are a snow formation found at high altitudes. They take the form of tall thin blades of hardened snow or ice closely spaced with the blades oriented towards the general direction of the sun. Penitentes can be as tall as a person. These pinnacles of snow or ice grow over all glaciated and snow covered areas in the Dry Andes above 4,000 m (Lliboutry 1954a, Lliboutry 1954b, Lliboutry 1965). They range in size from a few cm to over five metres. (Lliboutry 1965, Naruse and Leiva 1997).
Penitentes were first described in the literature by Darwin in 1839. On March 22, 1835, he had to squeeze his way through snowfields covered in penitentes near the Piuquenes Pass, on the way from Santiago de Chile to the Argentinian city of Mendoza, and reported the local belief (continuing to the present day) that they were formed by the strong winds of the Andes.
Lliboutry noted that the key climatic condition for the differential ablation that leads to the formation of penitentes is that dew point is always below freezing. Thus, snow will sublimate, because sublimation requires a higher energy input than melting. Once the process of differential ablation starts, the surface geometry of the evolving penitente produces a positive feedback mechanism, and radiation is trapped by multiple reflections between the walls. The hollows become almost a black body for radiation, while decreased wind leads to air saturation, increasing dew point temperature and the onset of melting. In this way peaks, where mass loss is only due to sublimation, will remain, as well as the steep walls, which intercept only a minimum of solar radiation. In the troughs ablation is enhanced, leading to a downward growth of penitentes. A mathematical model of the process has been developed by Betterton (2001), although the physical processes at the initial stage of penitente growth, from granular snow to micropenitentes, still remain unclear. The effect of penitentes on the energy balance of the snow surface, and therefore their effect on snow melt and water resources have been described by Corripio (2003) and Corripio and Purves (2005).
Keajaiban alam yang tinggal kenangan karena dihancurkan oleh letusan gunung berapi tarawera pada tahun 1886, Fenomena alam air hangat ini terbentuk dari semburan geyser yang melintas menuruni lereng bukit meninggalkan ketebalan es. Kolam air hangat terbesar ini tercatat 3 hektar, sebelum kehancuranya fenomena ini masuk kedalam “The Eighth Wonder of the World”.
New Zealand’s Pink and White Terraces, or Otukapuarangi (“fountain of the clouded sky”) and Te Tarata (“the tattooed rock”) in Māori, were considered a natural wonder. They were thought to have been completely destroyed by a violent volcanic eruption in 1886, but researchers discovered portions of the Pink Terraces on the bottom of Lake Rotomahana in 2011. The Pink and White terraces have been dubbed by a number of people as “The Eighth Wonder of the World”.
The terraces, located on the edges of Lake Rotomahana near Rotorua, were New Zealand’s most famous tourist attraction. They were attracting tourists from Europe in the early 1880s, when New Zealand was still relatively inaccessible and when passage took several months by sailing ship.
The Pink and White Terraces were the only New Zealand example of travertine terrace formations; they were formed by geothermally heated water containing large amounts of siliceous sinter regularly spouting from two geysers located beside Lake Rotomahana and cascading down a hill slope, leaving thick pink and white silica deposits that formed terraces enclosing pools of water. The White Terraces were the larger and more beautiful formation, covering 3 hectares and descending 30 metres, while the Pink Terraces were where people went to bathe.
The terraces were thought to have been destroyed around 3 am on 10 June 1886 as Mount Tarawera’s eruption spread from the summit, five kilometres to the north, down to Lake Rotomahana. The volcano belched out hot mud, red hot boulders and immense clouds of black ash from a 17 kilometre rift that crossed the mountain, passed through the lake, and extended beyond into the Waimangu valley. The eruption also buried several villages including the Māori and European settlement of Te Wairoa, killing approximately 120 people. After the eruption, a crater over 100 metres deep encompassed the former site of the terraces. After some years this filled with water to form a new Lake Rotomahana, 30 metres higher and much larger than the old lake.
A team including researchers from GNS Science, Woods Hole Oceanographic Institution, Lamont-Doherty Earth Observatory, and Waikato University were mapping the lake floor when they discovered a portion of the Pink Terraces in early 2011. The lower two tiers of the terraces were found in their original location at a depth of 60 metres (200 ft). It is unclear whether other tiers may have survived but been buried by ash or sediments.
The world famous Pink and White Terraces were considered to be the eighth wonder of the natural world and were New Zealand’s most famous tourist attraction. Unfortunately they were completely destroyed by a volcanic eruption on the 10th June 1886, at 3:00 am by Mt Tarawera, which violently erupted, belching out hot mud, red hot boulders and immense clouds of black ash. Several hours later, the bed of Lake Rotomahana blew out, burying the Maori villages of Moura and Te Ariki under a deep layer of liquid mud, stones and ash. The Mount Tarawera eruption was New Zealand’s most violent and destructive volcanic eruption in recent history. Mount Tarawera is 30 kilometres from Rotorua amidst the North Island’s volcanic- thermal region. This eruption caused approximately 153 deaths. The explosions were heard as far away as Auckland to the North and Christchurch to the South, and were thought to come from a ship in distress, whilst many in the Manawatu believed that the visiting Russian man-of-war, Vestnick was bombarding Wanganui. In Rotorua, no one was in any doubt as to what was happening.
Scientists are to use unmanned submarines to search a Rotorua lake for traces of the famed Pink and White Terraces, which were promoted as a tourism wonder before vanishing during the 1886 eruption of Mt Tarawera. Two torpedo-like unmanned underwater vehicles will be used to map the bottom of Lake Rotomahana as New Zealand and American researchers map hydrothermal vents on the lake bed, about 22km southeast of Rotorua. The lake was enlarged to its present 3km-by-6km size during the Tarawera eruption, from the Rotomahana and Rotomakariri lakes. The pink terraces were originally on the west bank of Lake Rotomahana and the white ones were on the north side, and researchers said there was a possibility parts survived the eruption, particularly the white terraces, which were protected from the explosion by a ridge. At the time, they were the largest silica terraces in the world and represented an enormous flow of geothermal fluid into the lake from vents on land. Now they are thought to be covered by at least 50m of lake water plus an additional sediment layer of unknown thickness.
Fenomena di atas memang luar biasa dan tentu saja langka. Namun, fenomena ini sebenarnya adalah fenomena atmosferik yang telah dikenal dengan baik di dunia sains. Nama fenomena itu adalah Sun Dog yang terlihat bersamaan dengan Parhelic Circle. Kadang sering juga disebut dengan fenomena matahari kembar. Fenomena Sun Dog (Sundog) yang kadang juga disebut dengan Parhelion adalah sebuah fenomena ketika kita bisa melihat adanya kumpulan cahaya tambahan di kedua sisi matahari. Kadang, kumpulan cahaya ini bisa terlihat seperti bola yang membuat kita berpikir kalau cahaya ini adalah matahari tambahan.
“Matahari tambahan” itu terlihat seperti seekor anjing yang duduk manis di sebelah tuannya, sang matahari. Fenomena ini hanya terjadi pada kondisi atmosferik yang sangat langka. Proses terjadinya sebuah ilusi optik di atmosfer. Sun Dog terjadi ketika cahaya matahari bersinar menembus kumpulan lempeng es kristal hexagonal yang tersusun secara horizontal di langit yang mengakibatkan cahaya itu dibelokkan dengan sudut minimum 22 derajat.
Proses ini bisa disamakan dengan proses terciptanya pelangi yang terbentuk karena cahaya matahari yang menyinari tetesan air di angkasa. Fenomena ini bisa muncul dimana saja dan kapan saja. Namun, ia akan lebih mudah terlihat ketika matahari berada pada posisi yang lebih rendah di Horizon (saat terbit atau terbenam). Pada matahari terbit, matahari akan naik semakin tinggi, Sun Dog pun akan bergeser dari sudut 22 derajat. Ketika matahari menjadi lebih tinggi lagi, Sun Dog pun lenyap. Umumnya Sun Dog berwarna merah ketika ia berada pada jarak terdekat dari matahari. Ketika ia semakin menjauh dari matahari, warnanya akan berubah mengarah ke biru.
Parhelic Circle adalah garis lengkung berwarna putih yang menembus matahari. Kita bisa melihatnya dengan jelas di rekaman di atas. Walaupun seringkali hanya terlihat sepotong, kadang, garis lengkung ini bisa membentuk sebuah lingkaran sempurna di langit. Sama seperti Sun Dog, Parhelic Circle juga terbentuk karena cahaya matahari yang dibelokkan oleh es kristal hexagonal. Namun, jika untuk mendapatkan Sun Dog kita harus memiliki es kristal hexagonal yang horizontal, maka untuk mendapatkan Parhelic Circle, es kristal hexagonal tersebut harus berada pada posisi vertikal atau hampir vertikal. Fenomena Sun Dog kadang bisa terlihat tanpa Parhelic Circle seperti yang terlihat pada Sun Dog di kota Harbin di atas, tetapi juga bisa terlihat bersama Parhelic Circle. Jika keduanya bergabung, maka kita mendapatkan sebuah orkestra bisu di langit.
Fenomena itu dinamakan sun dog atau anjing penjaga matahari. Cahaya tersebut biasa muncul di kanan kiri halo sehingga sering dianggap matahari meskipun memiliki ukuran lebih kecil. Kejadian ini disebabkan oleh pembiasan cahaya matahari oleh kristal es. Biasanya muncul di arah ufuk di mana matahari terbit belum terlalu jauh dari horizon atau kaki langit.Ketentuannya, di sekitar arah matahari muncul kristal-kristal es yang membiaskan cahaya. Biasanya, terjadi dua fenomena yaitu halo dan sun dog. Untuk halo sendiri, Indonesia sering mengalami kejadian yang sama meskipun tidak dengan sun dog. Ini sekadar pembiasan cahaya matahari yang muncul akibat kondisi lapisan atas awan cyrus sangat dingin.
A sun dog or sundog (scientific name parhelion, plural parhelia, from Greek parēlion, (παρήλιον), παρά(beside) + ήλιος(sun), “beside the sun”; also called a mock sun’ or a phantom sun') is an atmospheric phenomenon that creates bright spots of light in the sky, often on a luminous ring or halo on either side of the sun.
Sundogs may appear as a colored patch of light to the left or right of the sun, 22° distant and at the same distance above the horizon as the sun, and in ice halos. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sundogs are best seen and are most conspicuous when the sun is low.
Sundogs are made commonly of plate-shaped hexagonal ice crystals in high and cold cirrus clouds or, during very cold weather, by ice crystals called diamond dust drifting in the air at low levels. These crystals act as prisms, bending the light rays passing through them with a minimum deflection of 22°. If the crystals are randomly oriented, a complete ring around the sun is seen — a halo. But often, as the crystals sink through the air they become vertically aligned, so sunlight is refracted horizontally — in this case, sundogs are seen.
As the sun rises higher, the rays passing through the crystals are increasingly skewed from the horizontal plane. Their angle of deviation increases and the sundogs move further from the sun. However, they always stay at the same elevation as the sun.
Sundogs are red-colored at the side nearest the sun. Farther out the colors grade through oranges to blue. However, the colors overlap considerably and so are muted, never pure or saturated. The colors of the sundog finally merge into the white of the parhelic circle (if the latter is visible).
It is theoretically possible to predict the forms of sundogs as would be seen on other planets and moons. Mars might have sundogs formed by both water-ice and CO2-ice. On the giant gas planets — Jupiter, Saturn, Uranus and Neptune — other crystals form the clouds of ammonia, methane, and other substances that can produce halos with four or more sundogs.
Aristotle (Meteorology III.2, 372a14) notes that “two mock suns rose with the sun and followed it all through the day until sunset.” He says that “mock suns” are always to the side, never above or below, most commonly at sunrise or sunset, more rarely in the middle of the day. The poet Aratus (Phaenomena 880-891) mentions parhelia as part of his catalogue of Weather Signs; for him, they can indicate rain, wind, or an approaching storm.
A passage in Cicero’s On the Republic (54-51 BC) is one of many by Greek and Roman authors who refer to sun dogs and similar phenomena:
Be it so, said Tubero; and since you invite me to discussion, and present the opportunity, let us first examine, before any one else arrives, what can be the nature of the parhelion, or double sun, which was mentioned in the senate. Those that affirm they witnessed this prodigy are neither few nor unworthy of credit, so that there is more reason for investigation than incredulity.
The 2nd century Roman writer and philosopher Apuleius in his Apologia XV says “What is the cause of the prismatic colours of the rainbow, or of the appearance in heaven of two rival images of the sun, with sundry other phenomena treated in a monumental volume by Archimedes of Syracuse.”
Wars of the Roses
The prelude to the Battle of Mortimer’s Cross in Herefordshire, England in 1461 is supposed to have involved the appearance of a complete parhelion with three “suns”. The Yorkist commander, later Edward IV, convinced his initially frightened troops that it represented the Holy Trinity and Edward’s troops won a decisive victory.
Possibly the earliest clear description of a sundog is by Jacob Hutter, who wrote in his Brotherly Faithfulness: Epistles from a Time of Persecution:
My beloved children, I want to tell you that on the day after the departure of our brothers Kuntz and Michel, on a Friday, we saw three suns in the sky for a good long time, about an hour, as well as two rainbows. These had their backs turned toward each other, almost touching in the middle, and their ends pointed away from each other. And this I, Jakob, saw with my own eyes, and many brothers and sisters saw it with me. After a while the two suns and rainbows disappeared, and only the one sun remained. Even though the other two suns were not as bright as the one, they were clearly visible. I feel this was no small miracle …
The observation most likely occurred in Auspitz (Hustopeče), Moravia in very late October or very early November of 1533. The original was written in German and is from a letter originally sent in November 1533 from Auspitz in Moravia to the Adige Valley in Tyrol. The Kuntz Maurer and Michel Schuster mentioned in the letter left Hutter on the Thursday after the feast day of Simon and Jude, which is October 28. (This quote is also referenced by Fred Schaaf on page 94 of the November 1997 and December 1997 issues of Sky & Telescope.)
While mostly known and often quoted for being the oldest colour depiction of the city of Stockholm, Vädersolstavlan (Swedish; “The Sundog Painting”, literally “The Weather Sun Painting”) is arguably also one of the oldest known depictions of a sun dog. For two hours in the morning of April 20, 1535, the skies over the city were filled with white circles and arcs crossing the sky, while additional suns appeared around the sun. The phenomenon quickly resulted in rumours of an omen of God’s forthcoming revenge on King Gustav Vasa (1496–1560) for having introduced Protestantism during the 1520s and for being heavy-handed with his enemies allied with the Danish king.
Hoping to end speculations, the Chancellor and Lutheran scholar Olaus Petri (1493–1552) ordered a painting to be produced documenting the event. When confronted with the painting, the king, however, interpreted it as a conspiracy – the real sun of course being himself threatened by competing fake suns, one being Olaus Petri and the other the clergyman and scholar Laurentius Andreae (1470–1552), both thus accused of treachery, but eventually escaping capital punishment. The original painting is lost, but a copy from the 1630s survives and still can be seen in the church Storkyrkan in central Stockholm.
Nuremberg, Germany in 1561
On April 4, 1561, the skies over Nuremberg, Germany were filled with a multitude of celestial objects that were observed by many people in the city. The phenomenon was described in a News notice (an early form of newspaper) published in Nuremberg on April 14, 1561, along with a woodcut by Hans Glaser, depicted to the left.
Influence on Descartes in 1629
A set of powerful parhelia in Rome in the Summer of 1629 caused Descartes to interrupt his metaphysical studies and led to his work of natural philosophy called “The World”.
What is a sundog and what makes it happen?
A sundog on the right side of a halo around the sun. The globe blocking the sun sits atop a pedestal marking the South Pole. Photo courtesy of U.S. National Science Foundation, 11 Jan. 1999
A sundog is a rainbow-like spot in a cirrus cloud. Light shining through ice crystals in the cloud makes a sundog, much like light shining through raindrops makes a rainbow. “They are reddish on the side facing the sun and often have bluish-white tails stretching horizontally away from them,” say David Lynch and William Livingston in Color and Light in Nature.
Cirrus clouds–those high fleecy white bands or patches in the sky–are mostly tiny particles of ice. Ice can take on many forms and shapes. The cloud ice, however, is shaped like hex bathroom tiles or stubby pencils each no bigger than the tiniest grains of sand. These ice crystals bend light like a prism, disperse its colors, and cause sundogs.
When the crystals line up like tiles on a table, the light shining through makes sundogs. The horizontal crystals bend the light 22 degrees, say Lynch and Livingston, as the light enters and exits the crystal. Light colors fan out from the bending and display as a sundog.
Many years ago, the nature-essayist Hal Borland wrote in his book Sundial of the Seasons that “Sun dogs and moon dogs are beautiful accents to a winter day or night as the rainbow is to a showery Summer day.” Sun dogs usually appear in pairs, and are loyal to the sun (as moon dogs are loyal to the moon), sitting on each side of the solar orb along a horizontal line through the solar disk. Sun dogs appear in January, April, August, and October, the month does not really matter, but they are most regularly seen close to their solar master during winter months when the sun is low in the sky and ice crystals in the atmosphere are more common, but we can see them in any of the other seasons whenever cirrus clouds fuzz the sky above.
Sun dogs, or mock suns, are technically called solar parhelia (parhelia meaning “with the sun”) and appear as bright bursts of light formed when sunlight passes through ice crystals at the proper angle. Usually, cirrus clouds in front of the sun produce sun dogs, but other ice clouds, such as ice fog and diamond dust, may also generate them. Sun dogs are sometimes so brilliant that dazzled observers mistake them for the sun. They are often bright white but may show a partial spectrum of color with the red wavelengths on the edge nearest the sun. Sun dogs often have comet-like appearance with a bluish-white tail facing away from the sun.
Sun dogs are the second most frequent halo phenomena behind the 22o halo and often accompany that halo. The difference between sun dog and halo formation is the orientation of the ice crystals through which sunlight passes before reaching our eyes. Halo formation requires a mixture of random ice crystal orientations in the sky. But if the sky has only horizontally oriented, flat ice crystals, we just see a sun dog.
Ice crystals in the atmosphere are hexagonally shaped. Crystals forming most optical phenomena in the air are typically hexagonal rods, shaped like pencils, or flat, hexagonal plate patterns, like microscopic stop signs or dinner plates. When plate-shaped ice crystals fall unimpaired, drag forces automatically orient them horizontally so that their larger, flat surface parallels the earth like a large maple leaf drifting down from a tree.
Sun dogs emerge when sunlight passing through the ice plate’s thin sidefaces is refracted. The more perfectly aligned the falling crystals are to the horizontal, the more compact the resulting sun dog. Crystal misalignment from true horizontal will spread the sun dog vertically — its angular height being approximately four times the maximum crystal angular tilt.
Sun dogs frequently display a reddish tint on the side facing the sun and may sport bluish-white tails which stretch horizontally away from it. The degree to which colours are visible depends on the amount of wobble in the ice crystal’s fall: the more wobble, the more colour. The sun dog’s tail is formed by light passing through the crystal at angles other than the optimal deviation angle.
Sun dogs typically appear when the sun is low to the horizon, usually just prior to sunset or after sunrise, or during winter months at mid-latitudes. If the sun is low (horizon to about 15o above it), each sun dog is separated from the sun by 22o (or about two handsbreadth on extended arms), and both will lie on the circle of the 22o halo if one is present.
Sun dogs form tightest to the sun at lowest solar altitudes, but they are never less than 22o from it. As the Sun climbs in the sky, the sun dogs slowly move away from the 22o separation, although they remain on the line through the sun parallel with the horizon. When the sun has climbed to more than 45o altitude, sun dogs are fainter and noticeably off the 22o circle, and they vanish altogether above 61o solar altitude.
Over two millennia ago, the Greeks recognized that haloes and sun dogs foretold rain. Today we known this is often a valid prediction, because haloes and sun dogs are produced by ice crystals that form the cirroform clouds which make up the typical cloud sequence preceding a precipitating warm front.
One last word. There are also moon dogs that appear alongside the moon and are formed by lunar light passing through ice crystals. Moon dogs (or paraselenae) are less commonly seen because the moon can only produce them when bright and because they appear during the night when most of us are asleep.
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