Saturday, 27 February 2021

Part of Russian spacecraft found on beach in Bahamas.

A spherical metal tank, believed to have come from a Russian spacecraft, has been found on a beach in the Bahamas. The object, a spherical metal ball, was found projecting from the white sand of a beach on Harbour Island on Wednesday 24 February, by British woman Manon Clarke, who was walking on the beach with her family. The ball bears an inscription in Russian which states that has an operating temperature range of between -170°C and -190°C, and capacity of 43 litres, a maximum weight of 41 kg, and was manufactured in 1998. This is typical of a hydrazine propellant tank, typically used in unmanned spacecraft, with Mark Morabito of Virgin Galactic, stating that he is 99% certain that this is what the object is.

 
A titanium tank with a Russian inscription found on a beach in the Bahamas this week. Manon Clarke/The Independent.

Spacecraft tend to contain a lot of thick-walled spherical tanks, which is the most stable shape for a tank containing liquids under pressure in a changing gravity field. Unfortunately this is also a good shape for surviving re-entry into the Earth's atmosphere, so as the amount of space junk orbiting the Earth increases, so does the number of metal spheres falling from the sky. As yet there have been no reported cases of death or serious injury caused by space junk, but it does seem to be an increasing hazard on Earth as well as in orbit, with several reports of damage to property now coming in each year.

 
The basic design of a hydrazine bladder tank, thought to be the type object found on a Bahamas beach this week. The tank comprises a tough, protective, outer shell, typically made of titanium, with a flexible bladder inside, which shrinks as the gas inside is expelled, maintaining a constant pressure. Ariane Orbital Propulsion Centre.

Exactly how the tank came to be on a beach in the Bahamas is less clear. No falling debris (which would resemble a meteorite to people on the ground) has been observed in the Bahamas recently, although it could have fallen at night and not been seen, or buried by the sand on the beach for several years. Alternatively, it could have fallen in the sea somewhere in the Atlantic or Caribbean and simply floated to its current position. Sarah Hudspith of the University of Leeds has suggested that it may have originated from Cuba, a Cold War ally of the Soviet Union, although the manufacture date, 1998, several years after the break up of the Soviet Union, would seem to make this less likely.

 
Local residents excavating a metal object found on a beach in the Bahamas this week. Manon Clarke/The Independent.

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Friday, 26 February 2021

NASA's Parker Solar Probe provides a new view of Venus.

NASA’s Parker Solar Probe captured stunning views of Venus during its close flyby of the planet in July 2020, according to a press release on 24 February 2021. Although the Parker Solar Probe’s focus is the Sun, Venus plays a critical role in the mission: The spacecraft whips by Venus a total of seven times over the course of its seven-year mission, using the planet’s gravity to bend the spacecraft’s orbit. These Venus gravity assists allow Parker Solar Probe to fly closer and closer to the Sun on its mission to study the dynamics of the solar wind close to its source.

But, along with the orbital dynamics, these passes can also yield some unique and even unexpected views of the inner solar system. During the mission’s third Venus gravity assist on 11 July 2020, the onboard Wide-field Imager for Parker Solar Probe, or WISPR, captured a striking image of the planet’s nightside from 12 381 km away. 

When flying past Venus in July 2020, Parker Solar Probe’s WISPR instrument, short for Wide-field Imager for Parker Solar Probe, detected a bright rim around the edge of the planet that may be nightglow, light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. Bright streaks in WISPR, such as the ones seen here, are typically caused by a combination of charged particles, called cosmic rays, sunlight reflected by grains of space dust, and particles of material expelled from the spacecraft’s structures after impact with those dust grains. The number of streaks varies along the orbit or when the spacecraft is traveling at different speeds, and scientists are still in discussion about the specific origins of the streaks here. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument. Guillermo Stenborg/Brendan Gallagher/Johns Hopkins University Applied Physics Laboratory/Naval Research Laboratory/NASA.

WISPR is designed to take images of the solar corona and inner heliosphere in visible light, as well as images of the solar wind and its structures as they approach and fly by the spacecraft. At Venus, the camera detected a bright rim around the edge of the planet that may be nightglow, light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. The feature appears dark because of its lower temperature, about 30° C cooler than its surroundings.

That aspect of the image took the team by surprise, said Angelos Vourlidas, the WISPR project scientist from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, who coordinated a WISPR imaging campaign with Japan’s Venus-orbiting Akatsuki mission. 'WISPR is tailored and tested for visible light observations. We expected to see clouds, but the camera peered right through to the surface.'

'WISPR effectively captured the thermal emission of the Venusian surface,' said Brian Wood, an astrophysicist and WISPR team member from the U.S. Naval Research Laboratory in Washington, D.C. 'It’s very similar to images acquired by the Akatsuki spacecraft at near-infrared wavelengths.'

This surprising observation sent the WISPR team back to the lab to measure the instrument’s sensitivity to infrared light. If WISPR can indeed pick up near-infrared wavelengths of light, the unforeseen capability would provide new opportunities to study dust around the Sun and in the inner solar system. If it can’t pick up extra infrared wavelengths, then these images, showing signatures of features on Venus’ surface, may have revealed a previously unknown 'window' through the Venusian atmosphere.

NASA’s Parker Solar Probe had an up-close view of Venus when it flew by the planet in July 2020. Some of the features seen by scientists are labeled in this annotated image. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument. Guillermo Stenborg/Brendan Gallagher/Johns Hopkins University Applied Physics Laboratory/Naval Research Laboratory/NASA.

'Either way,' Vourlidas said, 'some exciting science opportunities await us.'

For more insight into the July 2020 images, the WISPR team planned a set of similar observations of the Venusian nightside during Parker Solar Probe’s latest Venus flyby on 20 February 2021. Mission team scientists expect to receive and process that data for analysis by the end of April.

'We are really looking forward to these new images,' said Javier Peralta, a planetary scientist from the Akatsuki team, who first suggested a Parker Solar Probe campaign with Akatsuki, which has been in orbiting Venus since 2015. 'If WISPR can sense the thermal emission from the surface of Venus and nightglow, most likely from oxygen, at the limb of the planet, it can make valuable contributions to studies of the Venusian surface.'

Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins Applied Physics Laboratory designed, built and operates the spacecraft.

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Ebola Virus Disease outbreak reported in Guinea.

A new outreak of Ebola Fever has been reported in Guinea, according to the World Health Organization. On 14 February 2021, the Ministry of Health of Guinea informed the World Health Organization of a cluster of Ebola Virus Disease cases in the sub-prefecture of Gouécké in the Nzérékoré Region of Guinea between 18 January and 13 February 2021. The cases showed symptoms of diarrhea, vomiting and bleeding after attending the burial of another relative (a 51 year-old nurse) on 1 February 2021.

The index case of the cluster was a nurse who had originally presented at a health centre in Gouécké on 18 January 2021 with headache, physical weakness, nausea, vomiting, loss of appetite, abdominal pain, and fever. She was diagnosed with Typhoid. She sought a second consultation at a health facility in Nzérékoré on 23 January 2021 for fever, vomiting, liquid stools, and physical weakness, and she was diagnosed with Malaria. On 24 January she consulted a traditional practitioner in Nzérékoré, and she died on 28 January 2021. She was buried unsafely on 1 February in Gouécké. The other six cases are the five family members and the traditional practitioner she visited. 

Among the seven cases, five have died (4 probable and 1 confirmed). The other two confirmed cases are currently in isolation in dedicated health care facilities in Conakry and Gouécké, Nzérékoré region.  

The Ebolavirus species has not yet been determined. Additional laboratory analyses are on-going to ascertain Virus species.  

As of 15 February, one hundred and ninety-two contacts have been identified, including 164 contacts in N’Zérékoré Health District and 28 in Ratoma Health District, Conakry. To date, no contacts have been reported to have travelled in neighboring countries. However, Nzérékoré is the second-largest city in Guinea and lies at the intersection of roads from Ganta (in Liberia), Danané (Côte d’Ivoire), and roads to other major hubs in Guinea like Kankan and Macenta in (Guinea). Therefore, there is concern about the exportation of Ebola Virus Disease cases into the neighbouring countries. 

On 14 February 2021, following the declaration of the Ebola Virus Disease outbreak, the Ministry of Health of Guinea convened a crisis meeting.

The Ministry of Health of Guinea, World Health Organization, and Global Outbreak Alert and Response Network partners, have initiated measures to control the outbreak and prevent further spread. To coordinate the response, the Ministry of Health activated the national and district emergency management committees. They also advised the public to take measures to avert the spread of the disease, and to report any persons with symptoms to seek care. Multidisciplinary teams have been deployed to the field to; actively search and provide care for cases, trace and follow-up contacts, and sensitize communities on infection prevention and control.

Ebola Virus Disease is caused by RNA Viruses of the genus Ebolavirus. It has a reputation for being the world's deadliest viral disease, at least in part due to the 1995 film Outbreak, though this is probably slightly inaccurate as about 50% of victims survive, making it less deadly than diseases such as Rabies. However, it is extremely contagious, with know known cure, and has a tendency to rapidly overwhelm local health systems as health workers themselves are infected.

 
Electron micrograph of an Ebola Virus particle. Frederick Murphy/Centers for Disease Control and Prevention/Wikimedia Commons.

Ebola begins with a fever similar to that caused by Influenza or Malaria, which tends to come on rapidly two-to-three weeks after infection (during at least part of which time the patient is already infectious). This tends to be followed by extreme respiratory tract infection, headaches, confusion, rashes and tissue necrosis and heavy bleeding. Death is generally caused by multiple organ failure.

The only known treatment for Ebola is intensive rehydration, which can improve the survival prospects of patients greatly, accompanied by anticoagulants and procoagulants to mange the diseases attacks on the circulatory system, analgesia to cope with the pain of the disease and antibiotics and antimycotics to prevent secondary infection. Due to the highly contagious nature of the disease it is recommended that healthcare workers wear full-body protection to maintain a barrier between them and their patients; a daunting prospect in the tropical regions of Africa where the disease is endemic. 

Ebolavirus is thought to have a non-human animal vector, since its rapid onset and high mortality rate appears to preclude a permanent residence within Human hosts. Surveys of wild animals have found Ebola infections in Rodents and Great Apes, however these were affected by the disease in a similar way to Humans, and are therefore unlikely permanent hosts. The most likely vectors are thought to be Fruit Bats or small Primates, which are endemic to the areas where the disease occurs and which are widely eaten; cooking meat probably kills the virus, but there is a distinct danger of infection while preparing carcasses.  

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Mayamaea vietnamica: A new species of soil-dwelling Diatom from Vietnam.

The genus Mayamaea was proposed by Horst Lange-Bertalot in 1997. Initially, 13 taxa formerly attributed to Navicula sensu lato were included in the genus. Mayamaea includes small-celled species that are elliptical in shape. The main characteristic of the genus is the arrangement of the pore occlusions, which are hymenes that cover the areolae from the outside, as well as the presence of a pronounced sternum found in the vast majority of species. The location of the hymenes is an important characteristic that differentiates Mayamaea from the genera Eolimna and Sellaphora, otherwise these genera have much in common including the structure of the raphe, central pores and distal raphe ends. Therefore, accurate identification by morphological characteristics is possible only when studying the material using a scanning electron microscope. Currently, the genus has about 30 taxa. Species of the genus Mayamaea are distributed worldwide, though most species are known from Europe. The species Mayamaea agrestis was described from Southeast Asia (Indonesia).

Species of Mayamaea prefer humid terrestrial habitats, as well as freshwater ecosystems (oligotrophic and mesotrophic), including in the littoral zone of these environments. In discussing the ecology of the species, Carlos Barragán, Luc Ector and Carlos Wetzel suggest that soil habitats are typical for Mayamaea lacunolaciniata, Mayamaea muraliformis, Mayamaea terrestris, and Mayamaea petersenii. However, some other species have also been found in the soil. For example, Mayamaea atomus was found in the soil of paddy fields in Central Japan. A large number of Diatom species (147 taxa) were identified from cultivated soils in Podkarpacie Province, Poland, and the most numerous was Mayamaea atomus and 5 other species. Others species of Mayamaea were found as well, including Mayamaea agrestis, Mayamaea excelsa, Mayamaea permitis, Mayamaea cf econdita, and Mayamaea sp2. Jasper Foets, Carlos Wetzer, Adriaan Teuling, and Laurent Pfister found Mayamaea atomus as a dominant in the soil of the Attert River basin (Luxembourg). The authors revealed that Mayamaea agrestis was typically on agricultural grasslands, Mayamaea permitis was one of the most abundant species in the territory, and Mayamaea fossalis was found in undisturbed grassland soils.

In a paper published in the journal Algae on 21 December 2020, Elena Kezlya and Anton Glushchenko of the К.А. Timiryazev Institute of Plant Physiology, John Patrick Kociolek of the Museum of Natural History and Department of Ecology and Evolutionary Biology at the University of Colorado, Yevhen Maltsev and Nikita Martynenko, also of the К.А. Timiryazev Institute of Plant Physiology, Sergei Genkal of the Papanin Institute for Biology of Inland Waters, and Maxim Kulikovskiy, again of the К.А. Timiryazev Institute of Plant Physiology, describe a new species from the genus Mayamaea isolated from a soil sample from the territory of Cát Tiên National Park in Vietnam.

Cát Tiên National Park is located in southern Vietnam, 150 km northeast of Ho Chi Minh City. The park was established in 1978 and consists of three parts with a total area of 73 878 hectares (738.78 km²). The region belongs to the bioclimatic type of monsoon tropical climate with summer rains. Relative humidity, as a rule, always exceeds 70%, with an average annual temperature of about 26°C. From December to March there is almost no rainfall. Southwest monsoons last eight months, from April to November, when most of the precipitation is observed. The wet season peaks in August-September. At this time of the year, up to 400-450 mm of precipitation falls per month, which leads to flooding of a significant part of the park. The main part of the territory is occupied by forests, which are of the monsoon, semi-deciduous type. These forests are characterized by high biological diversity and high productivity, second only to moist tropical forests in this respect.

 
Geographical position of the studied area. Kezlya et al. (2020).

The sample used was collected on 9 June 2018 from the Cát Tiên National Park, Đồng Nai Province, Vietnam and designated No. 06460. It was comprised examof wet soil, which had a pH of 6.5. Samples in general were taken as follows: first, the surface of the test site was examined in order to detect macrogrowth of algae, then a combined sample was taken from an area of 10-30 m² using the metal scoop or shovel. The composite sample consists of 5-10 individual samples. For an individual sample, the topsoil was removed from an area of 5 to 20 cm². After selection, the instruments were cleaned and sterilised with ethanol. Samples were placed in plastic zip bags, labeled. Immediately after the selection, the absolute humidity was determined in the laboratory room by the 'hot drying' method, then air dried and packaged.

The new species is named Mayamaea vietnamica, in reference to the country where it was discovered, and the specimens were placed in the Collection of Maxim Kulikovskiy at the Herbarium of the К.А. Timiryazev Institute of Plant Physiology.

Under light microscope the cells are solitary, rectangular in girdle view. One H-shaped plastid, with one arm lying against each side of the girdle, connected by a narrow central isthmus. Valves small, from almost linear to elliptical and oval (29 specimens) with pronounced sternum and broadly rounded ends. Length 9.1-10.5 μm, breadth 3.9-4.8 μm. Raphe narrow, linear. Central area more or less expressed, rounded to asymmetrical, rarely transversally elongated, and bordered on each margin by 3 shortened striae and/or 3 isolated areolae. Axial area tapers from the central area, becoming narrower towards the ends. The striae are radiate throughout the valve, 19-22 in 10 μm. Areolae coarse, clearly visible in light microscope.

 
Mayamaea vietnamica Strain VP 1, slide No. 06460. Light microscopy, differential interference contrast. (A) & (C)-(Z) Valves face. (A)-(H) Live cells with chloroplast structure. (B) Сell in girdle view. (I)-(Z) Size diminution series. (K) Holotype. Scale bar represents: 10 μm. Kezlya et al. (2020).

Under scanning electron microscope in external view the raphe is narrow, linear. Proximal raphe ends straight, drop-shaped. Distal raphe fissures bending strongly to the same side of valve mantle. Striae composed in 1-3 round areolae, not extending to valve margin. Areolae round, covered by individual hymenes.

 
Mayamaea vietnamica. Strain VP 1, slide No. 06460. Scanning electron microscopy, external views. (A) & (B) Whole valve. Areola occluded by hymen (arrow). (C) Central area. (D) Valve end. Scale bars represent: (A) & (B) 1 μm; (C) & (D) 0.5 μm. Kezlya et al. (2020).

Under scanning electron microscope in internal view the raphe is narrow, linear. Proximal valve ends slightly deflected to one side. Distal raphe ends terminating in small helictoglossae.

 
Mayamaea vietnamica. Strain VP 1, slide No. 06460. Scanning electron microscopy, internal views. (A) Whole valve. (B) Central area. (C) & (D) Valves ends. Scale bars represent: (A) 1 μm; (B)-(D) 0.5 μm. Kezlya et al. (2020).

Phylogenetic analysis of molecular sequence data shows that Mayamaea vietnamica is part of a branch with other species of Mayamaea. The branch with Mayamaea species is well-supported and independent from other branches. Closely related to the monophyletic group of Mayamaea species is a branch with strains of species from the genera Sellaphora and Eolimna. The branch containing these genera also has high statistical support. Six strains of Mayamaea permitis are divided in two branches in Kezlya et al.'s molecular tree. This suggests the presence of at least two cryptic species from specimens whose morphology suggest they could be assigned to the taxon Mayamaea permitis sensu lato. Mayamaea fossalis is close to two strains of Mayamaea permitis, however a difference between these species is supported by high statistical support. This result shows that these two species are independent taxa based on Kezlya et al.'s molecular investigation.

 
Bayesian tree of Mayamaea vietnamica (indicated in bold) constructed from a concatenated alignment of 107 partial rbcL and partial 18S rDNA sequences of 1380 characters. Values above the horizontal lines are bootstrap support from RAxML analyses (those below 50 are not shown); values below the horizontal lines are Bayesian posterior probabilities (those below 90 are not shown). All sequences have strain numbers (if available) and GenBank numbers. Species from the centric diatoms were used as an outgroup. Asterisks represent 100% statistical support. Kezlya et al. (2020).

Mayamaea vietnamica possesses all of the typical characters of the genus Mayamaea. These features include hymenes that covers the areolae from the outside, uniseriate striae, large areolae, small size, as well as the presence of a pronounced sternum. Our new species is morphologically similar to some known species from the genus Mayamaea, but it differs from them by both quantitative and qualitative features. The results of Kezlya et al.'s molecular investigation show the new species is part of an independent branch the includes three taxa. Mayamaea vietnamica is more closely related to Mayamaea terrestris than either is to Mayamaea atomus. Additionally, Mayamaea permitis and Mayamaea fossalis were included in the molecular investigation. The lineage of Mayamaea taxa is part of a broader monophyletic group that includes species of the genera Sellaphora, Eolimna and Rossia. However, the results of Kezlya et al.'s molecular investigation show that there is high statistical support for recognising Mayamaea as a genus distinct from these other genera.

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Thursday, 25 February 2021

Fireball meteor over Alberta.

Witnesses across the Alberta, British Columbia, Saskatchewan, and Montana have reported observing a bright fireball slightly after 6.20 pm local time (slightly after 1.20 pm GMT) on Monday 22 February 2021. The fireball is described as having moved from southheast to northwest, appearing over Val Soucy and vanishing to the north of Armstrong Lake. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry. 

 
Meteor seen from Oktoks in Alberta on 22 February 2021. Brenda Honish/American Meteor Society.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as an luminous object. However, this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).
 
 
Heat map  showing areas where sightings of the meteor were reported (warmer colours indicate more sightings), and the apparent path of the object (blue arrow). American Meteor Society.
 
These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.

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Landslide kills at least six at illegal gold mine in Cenral Sulawesi.

Six people have been confirmed dead, fifteen have been dug out alive, and one is still missing following a landslide at an illegal gold mine in the village of Buranga in Central Sulawesi, Indonesia, on Thursday 24 February 2021. The landslide is thought to have been caused by a combination of heavy rainfall associated with the the Northeast Monsoon, according to Fatmawati, a spokeswoman for the Badan Nasional Penanggulangan Bencana. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

   

Rescue workers at an illegal gold mine in Central Sulawesi, following a landslide on 25 February 2021. AFP.

Indonesia's large size, mineral richness, and poor population make unlicensed mining a widespread problem in the country, with illegal mines typically dug with hand tools and located in remote locations where authorities are unlikely to spot them (though some such operations are larger and more blatant in nature). Such mines tend to take few health and safety precautions, and are often dug by people with only a limited understanding of the structural geology of the area, making accidents extremely common, in many cases without help ever arriving due to the hidden nature of the mines. Such mines also present an environmental threat, producing waste which is often toxic, and contributing to deforestation, which can destabilise hillslopes, placing the miners at further risk.

 
The approximate location of the 25 February 2021 Central Sulawesi landslide. Google Maps.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

 
Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Sulawesi has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from  the South China Sea that lasts from November to February and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest.

 
The winds that drive the Northeast and Southwest Monsoons in Southeast Asia. Mynewshub.

Indonesia, and other countries of the western Pacific margin, are experiencing a particularly wet year, due to a prevailing La Niña weather system over the Pacific. The La Niña weather system is the opposite of the El Niño weather system, in which unusually cold surface temperatures spread across the equatorial Pacific from the upwelling zone on the South American coast. This traps warm water from the western Pacific, preventing it from spreading east and warming the central Pacific. This leads to lower evaporation over the (cooler) east Pacific, leading to low rainfall on the west coast of South America, and higher evaporation over the (warmer) west Pacific, leading to higher rainfall over East and Southeast Asia and northern Australia.

 
The effects of a La Niña weather system in December-February. NOAA.

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