O Mekong, Mecom ou Mecão é um dos maiores rios do mundo e está localizado no sudeste asiático.
Com um comprimento variável entre 4350 e 4990 km, é o 13.° mais
longo e 10.° mais volumoso (descarrega 475 km³ de água anualmente) rio
do mundo, drenando uma área de 795 000 km². Nasce no Planalto do Tibete e depois percorre a província chinesa de Yunnan, além de Myanmar, Tailândia, Laos, Camboja e Vietnã.
O nome Mekong vem dos idiomas tailandeses e significa Mae Nam Khong, onde Mae é traduzido como Mãe, e Nam como água.
A bacia do Mekong tem uma das biodiversidades mais ricas do mundo. Mais
de 1200 espécies de peixe já foram descobertas na área e são uma fonte
vital para a dieta da população local.
No Mekong superior, ao longo da porção nordeste, na fronteira com
o Laos, o rio é relativamente limpo e possui uma fluidez considerável. A
água tende a ser neutra com um pH
variando de 6,9 a 8,2 e o nível de nutrientes é baixo. Na parte baixa
do Mekong, a água é turva, especialmente durante a época de chuvas.
Devido a erosão dos barrancos ao longo da margem, a água passa a ter uma
coloração amarelada, cor de terra. A temperatura do rio varia de 21,1 a
27,8 °C e o pH entre 6,2 e 6,5.
Nesse rio, à altura da Tailândia com o Laos ocorre um fenômeno em
que esferas flamejantes saem dele e ascendem ao céu. Esse evento é
associado à serpente mitológica Naga. Os cientistas tailandeses não
chegaram a uma explicação plausível sobre as bolas de fogo. Em 2003, uma
equipe de cientistas do Ministério de Ciência e Tecnologia da Tailândia
não pôde chegar a nenhuma conclusão, embora tenha levantado a hipótese
de que este fenômeno fosse produto da ignição de gases de metano e nitrogênio originados por bactérias no fundo do rio.
segunda-feira, 15 de outubro de 2018
Mount Everest: World's Highest Mountain
By Kim Ann Zimmermann, Live Science Contributor |
Reaching 29,029 feet (8,848 meters) above sea level, Mount Everest is
the highest mountain on Earth. Located in the Mahalangur section of the
Himalayas, the mountain's summit straddles the border separating China
and Nepal.
The mountain's height was first determined in 1856. The Great
Trigonometric Survey of British India pegged the mountain, known to them
as Peak XV, at 29,002 feet (8,840 meters). But those surveyors were at a
disadvantage because Nepal would not grant them entry due to concerns
that the country would be invaded or annexed. The current accepted
elevation was determined by an Indian survey in 1955 and backed up by a
1975 Chinese measurement.
Lit by the sun, Everest's northeast ridge, the place George Mallory and Andrew Irvine were last seen alive.
Credit: John L. Semple.
In 1865, Andrew Waugh, the British Surveyor General of India, suggested
that the mountain be named after his predecessor in the job, Sir George
Everest. The Tibetans had referred to the mountain as "Chomolungma," or
Holy Mother, for centuries, but Waugh did not know this because Nepal
and Tibet were closed to outsiders.
Climbing Mount Everest
Mount Everest attracts experienced mountaineers as well as
less-seasoned climbers who typically enlist guides known as sherpas.
Climbing more than 8,000 feet is no easy feat. Altitude sickness,
weather and wind are the major roadblocks to making the summit for most
climbers. More than 5,000 people have climbed Everest and 219 have died
trying. About 77 percent of those ascents have been accomplished since
2000. In 2007, a record number of 633 ascents were recorded.
Mount Everest has two main climbing routes, the southeast ridge from
Nepal and the north ridge from Tibet. Today, the southeast ridge route,
which is technically easier, is more frequently used.
The northern approach was discovered in 1921 by George Mallory during
the British Reconnaissance Expedition, which was an exploratory
expedition, not intended to attempt the summit. Mallory was famously,
perhaps apocryphally, quoted as answering the question "Why do you want
to climb Mount Everest?" with the reply "Because it's there."
In 1922, Brit George Finch attempted an ascent using oxygen for the
first time, but the expedition was thwarted by an avalanche.
In June 1924, Mallory and Andrew Irvine did not survive their attempt
to reach to the summit. A 1999 expedition found Mallory's body.
Early expeditions in the 1920s and 1930s attempted to make the ascent
from the Tibetan side but access was closed after Tibet came under
Chinese control in 1950. This spurred Bill Tilman and a small party that
included Charles Houston, Oscar Houston and Betsy Cowles, to approach
Everest through Nepal along the route that has developed into the
standard approach to Everest from the south.
In 1952, members of a Swiss expedition led by Edouard Wyss-Dunant, were
able to reach a height of about 28,199 feet (8,595 meters) on the
southeast ridge, setting a new climbing altitude record. Tenzing Norgay,
a member of this expedition and a Nepali sherpa, took part in the
British expedition the following year.
In 1953, a British expedition led by John Hunt, returned to Nepal. Hunt
selected two climbing pairs to attempt to reach the summit. The first
pair (Tom Bourdillon and Charles Evans) came within 300 feet (100
meters) of the summit but were turned back due to oxygen problems. Two
days later, the second pair, Edmund Hillary and Tenzing Norgay, reached
the summit, took some pictures and left some sweets and a cross.
Life on Everest
Mount Everest is surrounded by a number of substantial peaks, including
Lhotse, (27,940 feet/8,516 meters); Nuptse, (25,771 feet/7,855 meters);
and Changtobse, (24,870 feet/7,580 meters).
Those higher altitudes cannot support animal life or vegetation;
however, birch, juniper, blue pines, firs, bamboo and rhododendron grow
in the lower areas. There are no plants above 18,690 feet (5,750
meters).
Musk deer, wild yak, red panda, snow leopard and Himalayan black bears
inhabit lower altitudes. There are also small numbers of Himalayan
thars, deer, langur monkeys, hares, mountain foxes, martens, and
Himalayan wolves.
Mountain milestones
Other milestones among Mount Everest expeditions include:
May 20, 1965: Sherpa Nawang Gombu becomes the first person to reach the summit twice.
May 16, 1975: Junko Tabei of Japan becomes the first woman to summit Everest.
May 3, 1980: Japanese climber Yasuo Kato is the first non-Sherpa to
reach the summit a second time, following his original 1973 summit.
Aug. 20, 1980: Reinhold Messner is the first person to reach the summit solo.
1996 climbing season: 16 people die while climbing on Mount Everest,
the highest number of fatalities in a single year. Eight climbers die on
May 10 during a storm. One of the survivors, Jon Krakauer, a journalist
on assignment for "Outside" magazine, wrote the bestseller "Into Thin
Air" about his experience.
May 22, 2010: Apa Sherpa, who first summitted on May 10, 1990, reaches the summit a 20th time.
China
Tailândia
Laos
