cloud

                                                           CLOUD

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Cumuliform cloudscape over Swifts Creek, Australia

In meteorology, a cloud is an aerosol comprising a visible mass of liquid droplets or frozen crystalsmade of water or various chemicals. The droplets or particles are suspended in the atmosphere above the surface of a planetary body.^[1] Terrestrial cloud formation is the result of air in any of the lower three principal layers of Earth's atmosphere (collectively known as the homosphere) becoming saturated due to either or both of two processes: cooling of the air and adding water vapor.

Clouds in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names due to the universal adaptation of Luke Howard's nomenclature. It was formally proposed in December 1802 and published for the first time the following year. It became the basis of a modern international system that classifies these tropospheric aerosols into several physical forms which can be found at various altitude levels or étages.

One physical form appears as non-convective stratiform sheets in stable air. If the airmass is slightly or partly unstable, limited-convective stratocumuliform rolls or ripples may appear. Both these layered forms have low, middle, and high-étage variants. Cloud types in the two upper étages are identified respectively by the prefixes alto- and cirro-. Thin or occasionally dense cirriform filaments are found only at high altitudes of the troposphere and may form in stable or partly unstable air. More generally unstable air tends to favor the formation of free-convective low or multi-level cumuliform heaps. Strong airmass instability or cyclonic lift can produce storm clouds with significant vertical extent through more than one étage. Prefixes are then used whenever necessary to express variations or complexities in their physical structures. These include cumulo- for complex highly unstable cumulonimbiform thunder clouds, and nimbo- for stable multi-étage stratiform layers with sufficient vertical depth to produce moderate to heavy precipitation. This cross-classification of forms and étages produces ten basic genus-types or genera, most of which can be divided into sub-types consisting of species that are often subdivided into varieties where applicable.

Clouds that form above the troposphere have common names for their main types, but are sub-classified alpha-numerically rather than with the elaborate system of Latin names given to cloud types in the troposphere. Clouds have been observed on other planets and moons within the Solar System, but, due to their different temperature characteristics, they are often composed of other substances such as methane, ammonia, and sulfuric acid as well as water.

History of cloud science and nomenclature

Aristotle and Theophrastus

Ancient cloud studies were not made in isolation, but were observed in combination with other weather elements and even other natural sciences. In about 340 BC the Greek philosopher Aristotle wrote Meteorologica, a work which represented the sum of knowledge of the time about natural science, including weather and climate. For the first time, precipitation and the clouds from which precipitation fell were called meteors, which originate from the Greek word meteoros, meaning 'high in the sky'. From that word came the modern term meteorology, the study of clouds and weather. Meteorologica was a work of intuitive rather than scientific study. Nevertheless, it was the first known work that attempted to treat a broad range of meteorological topics.^[4]

The book De Mundo (attributed to Pseudo-Aristotle) noted:^[5]

Cloud is a vaporous mass, concentrated and producing water. Rain is produced from the compression of a closely condensed cloud, varying according to the pressure exerted on the cloud; when the pressure is slight it scatters gentle drops; when it is great it produces a more violent fall, and we call this a shower, being heavier than ordinary rain, and forming continuous masses of water falling over earth. Snow is produced by the breaking up of condensed clouds, the cleavage taking place before the change into water; it is the process of cleavage which causes its resemblance to foam and its intense whiteness, while the cause of its coldness is the congelation of the moisture in it before it is dispersed or rarefied. When snow is violent and falls heavily we call it a blizzard. Hail is produced when snow becomes densified and acquires impetus for a swifter fall from its close mass; the weight becomes greater and the fall more violent in proportion to the size of the broken fragments of cloud. Such then are the phenomena which occur as the result of moist exhalation.

Several years after Aristotle's book, his pupil Theophrastus put together a book on weather forecasting called The Book of Signs. Various indicators such as solar and lunar halos formed by high clouds were presented as ways to forecast the weather. The combined works of Aristotle and Theophrastus had such authority they became the main influence in the study of clouds, weather and weather forecasting for nearly 2000 years.^[4]

Luke Howard and Jean-Baptiste Lamarck

After centuries of speculative theories about the formation and behavior of clouds, the first truly scientific studies were undertaken by Luke Howard in England and Jean-Baptiste Lamarck in France. Howard was a methodical observer with a strong grounding in the Latin language and used his background to classify the various tropospheric cloud types during 1802. He believed that the changing cloud forms in the sky could unlock the key to weather forecasting. Lamarck had worked independently on cloud classification the same year and had come up with a different naming scheme that failed to make an impression even in his home country of France because it used unusual French names for cloud types. His system of nomenclature included twelve categories of clouds, with such names as (translated from French) hazy clouds, dappled clouds and broom-like clouds. By contrast, Howard used universally accepted Latin, which caught on quickly after it was published in 1803.^[6] As a sign of the popularity of the naming scheme, the German dramatist and poet Johann Wolfgang von Goethe composed four poems about clouds, dedicating them to Howard. An elaboration of Howard's system was eventually formally adopted by the International Meteorological Conference in 1891.^[6]

First comprehensive classification

Altocumulus stratiformis duplicatus at Sunrise in the California Mojave Desert, USA

Howard's original system established three general cloud forms based on physical appearance and process of formation: cirriform(mainly detached and wispy), cumuliform or convective (mostly detached and heaped, rolled, or rippled), and non-convective stratiform(mainly continuous layers in sheets).^[7] These were cross-classified into lower and upper étages. Cumuliform clouds forming in the lower level were given the genus name cumulus from the Latin word for heap,^[8] and low stratiform clouds the genus name stratus from the Latin word for sheet or layer. Physically similar clouds forming in the upper étage were given the genus names cirrocumulus (generally showing more limited convective activity than low level cumulus) and cirrostratus, respectively. Cirriform clouds were identified as always upper level and given the genus name cirrus from the Latin for 'fibre' or 'hair'.

In addition to these individual cloud types; Howard added two names to designate cloud systems consisting of more than one form joined together or located in very close proximity. Cumulostratus described large cumulus clouds blended with stratiform layers in the lower or upper levels.^[9] The term nimbus was given to complex systems of cirriform, cumuliform, and stratiform clouds with sufficient vertical development to produce significant precipitation,^[6][10] and it came to be identified as a distinct nimbiform physical category.^[11]

Howard's successors

In 1840, German meteorologist Ludwig Kaemtz added stratocumulus to Howard's canon as a mostly detached low-étage genus of limited convection.^[12] It was defined as having cumuliform- and stratiform characteristics integrated into a single layer (in contrast to cumulostratus which was deemed to be composite in nature and could be structured into more than one layer).^[6] This led to the recognition of a stratocumuliform^[13] category that included rolled and rippled clouds classified separately from the more freely convective heaped cumuliform clouds.

Middle clouds over Santa Clarita, CA. Altocumulus floccus producing virga near top and middle of image merging into altostratus translucidus near horizon.

During the mid 1850s, Emilien Renou, director of the Parc Saint-Maur and Montsouris observatories, began work on an elaboration of Howard's classifications that would lead to the introduction during the 1870s of altocumulus (physically more closely related to stratocumulus than to cumulus) and altostratus. These were respectively stratocumuliform and stratiform cloud genera of a newly definedmiddle étage above stratocumulus and stratus but below cirrocumulus and cirrostratus.^[6]

In 1880, Philip Weilbach, secretary and librarian at the Art Academy in Copenhagen, and like Luke Howard, an amateur meteorologist, unsuccessfully proposed an alternative to Howard's classification. However, he also proposed and had accepted by the permanent committee of the International Meteorological Organization (IMO), a forerunner of the present-day World Meteorological Organization(WMO), the designation of a new free-convective vertical or multi-étage genus type, cumulonimbus, which would be distinct from cumulus and nimbus and identifiable by its often very complex structure (frequently including a cirriform top and what are now recognized as multiple accessory clouds), and its ability to produce thunder. With this addition, a canon of ten tropospheric cloud genera was established that came to be officially and universally accepted.^[6] Howard's cumulostratus was not included as a distinct type, having effectively been reclassified into its component cumuliform and stratiform genus types already included in the new canon.

In 1890, Otto Jesse revealed the discovery and identification of the first clouds known to form above the troposphere. He proposed the name noctilucent which is Latin for night shining. Because of the extremely high altitudes of these clouds in what is now known to be the mesosphere, they could become illuminated by the a sun's rays when the sky was nearly dark after sunset and before sunrise.^[14] Three years later, Henrik Mohn revealed a similar discovery of nacreous clouds in what is now considered the stratosphere.^[15]

In 1896, the first cloud atlas sanctioned by the IMO was produced by Teisserenc de Borte based on collaborations with Hugo H. Hildebrandsson. The latter had become the first researcher to use photography for the study and classification of clouds in 1879.^[6]

Alternatives to Howard's classification system were proposed throughout the 19th. centurey. Heinrich Dove of Germany and Elias Loomis of the United States came up with other schemes in 1828 and 1841 respectively, but neither met with international success.^[16] Additional proposals were made by Andre Poey (1863), Clemment Ley (1894), and H.H. Clayton (1896), but their systems, like earlier alternative schemes, differed too much from Howard's to have any success beyond the adoption of some secondary cloud types.^[6] However, Clayton's idea to formalize the division of clouds by their physical structures into cirriform, stratiform, "flocciform" (stratocumuliform)^[17] and cumuliform (with the later addition of cumulonimbiform), eventually found favor as an aid in the analysis of satellite cloud images.^[13]

20th-century developments

A further modification of the genus classification system came when an IMC commission for the study of clouds put forward a refined and more restricted definition of the genus nimbus which was effectively reclassified as a stratiform cloud type. It was then renamed nimbostratus and published with the new name in the 1932 edition of the International Atlas of Clouds and of States of the Sky.^[6] This left cumulonimbus as the only nimbiform type as indicated by its root-name.

On April 1, 1960, the first successful weather satellite, TIROS I (Television Infrared Observation Satellite), was launched from Cape Canaveral, Florida by the National Aeronautics and Space Administration (NASA) with the participation of The US Army Signal Research and Development Lab, RCA, the US Weather Bureau, and the US Naval Photographic Center. During its 78-day mission, it relayed thousands of pictures showing the structure of large-scale cloud regimes, and proved that satellites could provide useful surveillance of global weather conditions from space.^[18]

In 1976, the United Kingdom Department of Industry published a modification of the international cloud classification system adapted for satellite cloud observations. It was co-sponsored by NASA and showed a change in name of the nimbiform type to cumulonimbiform,^[13] although the earlier name and original meaning pertaining to all rain clouds can still be found in some classifications.^[19]

                                                     HEALTH

                          

Health is the level of functional or metabolic efficiency of a living organism. In humans it is the ability of individuals or communities to adapt and self-manage when facing physical, mental or social challenges.^[1] The World Health Organization (WHO) defined health in its broader sense in its 1948 constitution as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."^[2][3] This definition has been subject to controversy, in particular as lacking operational value and because of the problem created by use of the word "complete" ^[4] [5][6] Other definitions have been proposed, among which a recent definition that correlates health and personal satisfaction.^[7][8] Classification systems such as the WHO Family of International Classifications, including the International Classification of Functioning, Disability and Health (ICF) and the International Classification of Diseases (ICD), are commonly used to define and measure the components of health. Health is that balanced condition of the living organism in which the integral, harmonious performance of the vital functions tends to the preservation of the organism and the normal development of the individual.

Systematic activities to prevent or cure health problems and promote good health in humans are undertaken by health care providers. Applications with regard to animal health are covered by the veterinary sciences. The term "healthy" is also widely used in the context of many types of non-living organizations and their impacts for the benefit of humans, such as in the sense of healthy communities, healthy cities or healthy environments. In addition to health care interventions and a person's surroundings, a number of other factors are known to influence the health status of individuals, including their background, lifestyle, and economic, social conditions, and spirituality; these are referred to as "determinants of health." Studies have shown that high levels of stress can affect human health.

Maintaining health

Diet

Main articles: Healthy diet and Human nutrition

An important way to maintain your personal health is to have a healthy diet. A healthy diet includes a variety of plant-based and animal-based foods that provide nutrients to your body. Such nutrients give you energy and keep your body running. Nutrients help build and strengthen bones, muscles, and tendons and also regulate body processes (i.e. blood pressure). The food guide pyramid is a pyramid-shaped guide of healthy foods divided into sections. Each section shows the recommended intake for each food group (i.e. Protein, Fat, Carbohydrates, and Sugars). Making healthy food choices is important because it can lower your risk of heart disease, developing some types of cancer, and it will contribute to maintaining a healthy weight.^[31]

Exercise

Main article: Physical exercise

Physical exercise enhances or maintains physical fitness and overall health and wellness. It strengthens muscles and improves thecardiovascular system.

Sleep

Main articles: Sleep and Sleep deprivation

Sleep is an essential component to maintaining health. In children, sleep is also vital for growth and development. Ongoing sleep deprivation has been linked to an increased risk for some chronic health problems. In addition, sleep deprivation has been shown to correlate with both increased susceptibility to illness and slower recovery times from illness.^[32] In one study, people with chronic insufficient sleep, set as six hours of sleep a night or less, were found to be four times more likely to catch a cold compared to those who reported sleeping for seven hours or more a night.^[33] Due to the role of sleep in regulating metabolism, insufficient sleep may also play a role inweight gain or, conversely, in impeding weight loss.^[34] Additionally, in 2007, the International Agency for Research on Cancer, which is the cancer research agency for the World Health Organization, declared that "shiftwork that involves circadian disruption is probablycarcinogenic to humans," speaking to the dangers of long-term nighttime work due to its intrusion on sleep.^[35] In 2015, the National Sleep Foundation released updated recommendations for sleep duration requirements based on age and concluded that "Individuals who habitually sleep outside the normal range may be exhibiting signs or symptoms of serious health problems or, if done volitionally, may be compromising their health and well-being."^[36]

                                   MY COLLEGE      

                


              N S S COLLEGE NILAMEL

Malala Yousafzai S.St (Malālah Yūsafzay: Urdu, Pashto: ملاله یوسفزۍ‎ [məˈlaːlə jusəf ˈzəj];^[1] born 12 July 1997)^[2][3] is a Pakistani activist for female education and the youngest-ever Nobel Prize laureate.^[4] She is known mainly for human rights advocacy foreducation and for women in her native Swat Valley in the Khyber Pakhtunkhwa province of northwest Pakistan, where the localTaliban had at times banned girls from attending school. Yousafzai's advocacy has since grown into an international movement.

Her family runs a chain of schools in the region. In early 2009, when she was 11–12, Yousafzai wrote a blog under a pseudonym for the BBC detailing her life under Taliban occupation, their attempts to take control of the valley, and her views on promoting education for girls in the Swat Valley. The following summer, journalist Adam B. Ellick made a New York Times documentary^[3] about her life as the Pakistani military intervened in the region. Yousafzai rose in prominence, giving interviews in print and on television, and she was nominated for the International Children's Peace Prize by South African activist Desmond Tutu.

On the afternoon of October 9, 2012, Yousafzai boarded her school bus in the northwest Pakistani district of Swat. A gunman asked for her by name, then pointed a pistol at her and fired three shots. One bullet hit the left side of Yousafzai's forehead, travelled under her skin through the length of her face, and then went into her shoulder.^[5] In the days immediately following the attack, she remained unconscious and in critical condition, but later her condition improved enough for her to be sent to the Queen Elizabeth Hospital in Birmingham, England, for intensive rehabilitation. On 12 October, a group of 50 Islamic clerics in Pakistan issued a fatwāagainst those who tried to kill her, but the Taliban reiterated their intent to kill Yousafzai and her father, Ziauddin Yousafzai. The assassination attempt sparked a national and international outpouring of support for Yousafzai. Deutsche Welle wrote in January 2013 that Yousafzai may have become "the most famous teenager in the world."^[6] United Nations Special Envoy for Global Education Gordon Brown launched a UN petition in Yousafzai's name, demanding that all children worldwide be in school by the end of 2015; it helped lead to the ratification of Pakistan's first Right to Education Bill.^[7]

The 2013, 2014 and 2015 issues of Time magazine featured Yousafzai as one of "The 100 Most Influential People in the World". She was the winner of Pakistan's first National Youth Peace Prize, and the recipient of the 2013 Sakharov Prize. In July that year, she spoke at the headquarters of the United Nations to call for worldwide access to education, and in October the Government of Canada announced its intention that its parliament confer Honorary Canadian citizenship upon Yousafzai.^[8] In February 2014, she was nominated for the World Children's Prize in Sweden.^[9] Even though she was fighting for women's rights as well as children's rights, she did not describe herself as feminist when asked on Forbes Under 30 Summit in 2014.^[10][11] However, in 2015 Yousafzai told Emma Watson she decided to call herself a feminist after hearing Watson's speech at the UN launching the HeForShecampaign.^[12] In May 2014, Yousafzai was granted an honorary doctorate by the University of King's College in Halifax.^[13] Later in 2014, Yousafzai was announced as the co-recipient of the 2014 Nobel Peace Prize, along with Kailash Satyarthi, for her struggle against the suppression of children and young people and for the right of all children to education. Aged 17 at the time, Yousafzai became the youngest-ever Nobel Prize laureate.

Bird

Birds Temporal range: Late Cretaceous - Present,[1] 85–0 Ma PreЄ Є O S D C P T J K Pg N
1883

Birds (class Aves) are a group of endothermic vertebrates, characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strongskeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft)ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds or, less accurately, assongbirds.

Scientific consensus is that birds are the last surviving lineage of dinosaurs, having evolved from feathered dinosaur ancestors within the theropod group of saurischian dinosaurs. The fossil record indicates that true birds first appeared during the Cretaceous period,

around 100 million years ago.^[3] However, primitive bird-like "stem-birds" that lie outside class Aves proper, in the group Avialae, have been found dating back to the mid-Jurassic period.^[1] Many of these early stem-birds, such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks and long bony tails.^[1][4]

Birds have more or less developed wings; the only known groups without wings are the extinct moa andelephant birds. Bird wings, which evolved from forelimbs, enabled birds the ability of bird flight. The digestiveand respiratory systems of birds are also uniquely adapted for flight, although further speciation has led to some flightless birds, including ratites, penguins, and diverse endemic island species of birds. Some bird species of aquatic environments, particularly the aforementioned flightless penguins, and also members of theduck family, have also evolved for swimming. Birds, specifically Darwin's finches, played an important part in the inception of Darwin's theory of evolution by natural selection.

Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form ofculture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting,flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous("many females") or, rarely, polyandrous ("many males") breeding systems. Birds produce offspring by layingeggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring.

Many species of birds are economically important. Domesticated and undomesticated birds (poultry andgame) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertilizer. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourismindustry.