Volcanoes.............

               A volcano is a hole in Earth's surface through which magma (called lava when it reaches Earth's surface), hot gases, ash, and rock fragments escape from deep inside the planet. The word volcano also is used to describe the cone of erupted material (lava and ash) that builds up around the opening.

Volcanic activity is the main process by which material from Earth's interior reaches its surface. Volcanoes played a large part in the formation of Earth's atmosphere, oceans, and continents. When Earth was new, the superheated gases within it (including carbon dioxide) streamed out through countless volcanoes to form the original atmosphere and oceans.

Facts About Volcanoes

1.A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur.
2.In an eruption, gases and rock shoot up through the opening and spill over or fill the air with lava fragments. Eruptions can cause lava flows, hot ash flows, mudslides, avalanches, falling ash and floods.
3.The danger area around a volcano covers about a 20-mile radius.
4.Fresh volcanic ash, made of pulverized rock, can be harsh, acidic, gritty, glassy and smelly. The ash can cause damage to the lungs of older people, babies and people with respiratory problems.
5.Volcanic lightning occurs mostly within the cloud of ash during an eruption, and is created by the friction of the ash rushing to the surface. Roughly 200 accounts of this lightning have been witnessed live.

What are the different stages of volcanoes? 

Scientists have categorized volcanoes into three main categories: active, dormant, and extinct. An active volcano is one which has recently erupted and there is a possibility that it may erupt soon. A dormant volcano is one which has not erupted in a long time but there is a possibility it can erupt in the future. An extinct volcano is one which has erupted thousands of years ago and there’s no possibility of eruption.

Types of Volcanoes

Volcanoes are grouped into four types: cinder cones, composite volcanoes, shield volcanoes and lava volcanoes.

Cinder Cones
Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown into the air, cooled and fallen around the vent.

Shield volcanoes

Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. Basalt lava flows from these volcanoes are called flood basalts. The volcanoes that formed the basalt of the Columbia Plateau were shield volcanoes.

The base of the volcano increases in size over successive eruptions where solidified lava spreads out and accumulates. Some of the world's largest volcanoes are shield volcanoes.

Even though their sides are not very steep, shield volcanoes can be huge. Mauna Kea in Hawaii is the biggest mountain on Earth if it is measured from its base on the floor of the sea

Composite Volcanoes

A stratovolcano, also known as a composite volcano, is a tall, conical volcano. It is built up of many layers of hardened lava, tephra, pumice, and volcanic ash.

Unlike shield volcanoes, stratovolcanoes have a steep profile and periodic eruptions. The lava that flows from stratovolcanoes cools and hardens before spreading far. It is sticky, that is, it has high viscosity. The magma forming this lava is often felsic, with high-to-intermediate levels of silica, and less mafic magma. Big felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).

Two famous stratovolcanoes are Japan's Mount Fuji, and Vesuvius. Both have big bases and steep sides that get steeper and steeper as it goes near the top. Vesuvius is famous for its destruction of the towns Pompeii and Herculaneum in 79 AD, killing thousands.

Lava Volcanoes

Lava domes are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent. The eruption of Mount St. Helens in 1980 was caused in part by a lava dome shifting to allow explosive gas and steam to escape from inside the mountain.

How volcanoes form

According to the geologic theory called plate tectonics, Earth's crust is broken into various rigid plates that "float" on the surface of the planet. The plates move in response to intense pressure created underneath by the movement of currents carrying heat energy from the center of the planet to the surface. This pressure causes plates to move toward or away from each other (and also past each other in a horizontal motion).

Volcanoes form on land near coastal areas when a continental (land) plate and an oceanic plate converge or move toward each other. Since the oceanic plate is denser, it subducts or sinks beneath the continental plate. As the rock of this subducted oceanic plate is pushed farther and farther beneath the continent's surface, extremely high temperatures and pressure melt the rock. This creates hot, buoyant magma that then rises toward the surface. When the magma reaches the crust, it collects in a magma reservoir or chamber. When pressure inside the reservoir exceeds that of the overlying rock, magma is forced upward through cracks in Earth's crust.

Volcanic catastrophes

Numerous volcanoes erupt around the world every century, usually in sparsely populated areas. Even so, volcanoes have threatened human civilization throughout history and will do so as long as people live on Earth's often violent surface.

An ash fall from Mount Vesuvius buried the Roman city of Pompeii in a.d. 79. The volcano, which sent a column of hot ash 12 miles (19 kilometers) into the sky, struck down the people where they lived, preserving the shapes of their bodies where they fell in the ash. The nearby city of Herculaneum was covered by a pyroclastic flow that destroyed it in seconds. Pompeii remained buried until 1748, when construction workers first unearthed parts of the ancient city—much of it appearing as it did on the morning Vesuvius erupted.

On August 27, 1883, the volcanic island of Krakatoa in Indonesia erupted, blowing an ash cloud 50 miles (80 kilometers) high then collapsing into a caldera. The collapse was heard almost 2,500 miles (4,020 kilometers) away. Resulting tidal waves reaching 130 feet (40 meters) killed 36,000 people in coastal Java and Sumatra. Spectacularly weird sky phenomena from this eruption included brilliant green sunrises and moon-rises in the equatorial latitudes, followed by day-long blue sunlight and bright green sunsets.

On the morning of May 18, 1980, Mount St. Helens in Washington erupted with the force of more than 500 atomic bombs—one of the largest volcanic explosions in North American history. The blast, which sent a mushroom-shaped ash plume 12 miles (20 kilometers) high, reduced the summit (peak) by more than 1,300 feet (400 meters). Sixty people and countless animals were killed, and every tree within 15 miles (24 kilometers) was flattened. Ensuing landslides carried debris for nearly 20 miles (32 kilometers).

Volcanic benefits

The eruption of volcanoes through geologic time built the continents. The soil of some of the world's richest farmland draws its fertility from minerals provided by nearby volcanoes. The heat of magma boils water into steam that spins the turbines of geothermal power stations. Geothermal stations now light electric power grids in Iceland, Italy, New Zealand, and a other places. Enough heat flows from the world's volcanic regions and midoceanic ridges to power industrial civilization for several hundred million years. This power source awaits only the development of feasible geothermal technology.

Occurrence

Volcanoes are found in association with midocean ridge systems (see seafloor spreading) and along convergent plate boundaries, such as around the Pacific Ocean's "Ring of Fire" (see plate tectonics), the ring of plate boundaries associated with volcanic island arcs and ocean trenches surrounding the Pacific Ocean. Continental volcanoes are also associated with converging plate boundaries, such as the volcanoes of the Cascade Range along the W coast of the United States. Isolated volcanoes also form in the midocean area of the Pacific apparently unrelated to crustal plate boundaries. These sea mounts and volcanic island chains, such as the Hawaiian chain, may form from rising magma regions called hot spots; an example of a continental hot spot is found at Yellowstone National Park. 

Volcanic Cones and Craters

Shapes of volcanoes include composite cones, or stratovolcanoes, with steep concave sides such as Mt. St. Helens in the W United States; shield cones have gentle slopes and can be relatively large such as the Hawaiian Islands; and cinder cones as Parícutin in Mexico, with steep slopes made of cinderlike materials. Explosive eruptions build up steep-sided cones, while the nonexplosive ones usually form broad, low lava cones. Cones range in height from a few feet to nearly 30,000 ft (9 km) above their base. Usually the cone has as its apex a cavity, or crater, which contains the mouth of the vent. Such craters are typically less than 1 mi (1.6 km) across, but larger craters, called calderas, ranging in diameter from 3 mi to—in a few instances—50 mi (5–80 km), are formed by particularly large eruptions (see crater). 

Volcanic Eruptions

More than 500 volcanoes are known to have erupted on the earth's surface since historic times, and many more have erupted on the ocean floor unobserved by humans. Fifty volcanoes have erupted in the United States, which ranks third, behind Indonesia and Japan, in the number of historically active volcanoes. Of the world's active volcanoes, more than half are found around the perimeter of the Pacific, about a third on midoceanic islands and in an arc along the south of the Indonesian islands, and about a tenth in the Mediterranean area, Africa, and Asia Minor.

Evidence of extraterrestrial volcanic activity also has been found. Space probes have detected the remnants of ancient eruptions on earth's moon, Mars (which has the largest volcano in the solar system, Olympus Mons, 340 mi/550 km across and 15 mi/24 km high), and Mercury; these probably originated billions of years ago, since these bodies are no longer capable of volcanic activity. Triton (a satellite of Neptune), Io (a satellite of Jupiter), and Venus are known to be volcanically active. The volcanic processes that occur in the outer portion of the solar system are very different from those in the inner part. Eruptions on earth, Venus, Mercury, and Mars are of rocky material and are driven by internal heat. Io's eruptions are probably sulfur or sulfur compounds driven by tidal interactions with Jupiter. Triton's eruptions are of very volatile compounds, such as methane or nitrogen, driven by seasonal heating from the sun.

Terrestrial volcanic eruptions may take one or more of five chief forms, or phases, known as Hawaiian, Strombolian, Vulcanian, Peleean, and Plinian. In the Hawaiian phase there is a relatively quiet effusion of basaltic lava unaccompanied by explosions or the ejection of fragments; the eruptions of Mauna Loa on the island of Hawaii are typical. The Strombolian phase derives its name from the volcano Stromboli in the Lipari, or Aeolian, Islands, N of Sicily. It applies to continuous but mild discharges in which viscous lava is emitted in recurring explosions; the ejection of incandescent material produces luminous clouds. A more explosive volcanic eruption is the Vulcanian, where the magma (lava before emission) accumulates in the upper level of the vent but is blocked by a hardened plug of lava that forms between consecutive explosions. When the explosive gases have reached a critical pressure within the volcano, masses of solid and liquid rock erupt into the air and clouds of vapor form over the crater. The Peleean, derived from Mt. Pelée, is more violent, emitting fine ash; hot, gas-charged fragments of lava; and a characteristic superheated pyroclastic flow that travels downhill at great speed. Plinian, or Vesuvian eruptions, derives its name from Pliny the Younger, who described the eruption of Vesuvius in AD 79. The Plinian eruption is similar to Strombolian and Vulcanian eruptions with significant ash and pumice and pyroclastic flows, but it also produces a characteristic massive, sustained eruptive column of hot ash that can reach 28 mi (45 km) in height.

Eruptions are often accompanied by torrential rains caused by the condensation of steam. The erupted fragments vary in size, including minute particles of volcanic dust and ash, lapilli (cinders or pellets), bombs (rounded or ellipsoidal masses of hardened magma), and huge masses called blocks. Minute dust and ash and aerosols carried high into the earth's atmosphere can have a cooling effect on the climate, and significant amounts of chlorine and bromine gases ejected in large eruptions can reach the stratosphere and deplete the ozone layer. The dust and ash can also be a hazard to air travel. The 1783 eruption of Laki, S Iceland, had devastating effects on local livestock and, as result, the populace; the resulting sulfur dioxide haze that spread over parts of Europe is believed to have negatively affected the health of the inhabitants. 

Historical Volcanoes

Notable eruptions within historic times have been those of Vesuvius, in Italy (AD 79, 1906, and other times); Tambora, in Indonesia, where between 30 and 50 cu mi (125–210 cu km) of molten and shattered rock were blown into the air (1815); Krakatoa, near Java, material from which was sent 17 mi (27 km) into the atmosphere (1883); Parícutin, in Mexico, the volcano that began in a cornfield (1943); Hibok Hibok, on Camiguin island in the Philippines, which killed 84 people (1948); Besymianny, in Kamchatka, where 2 cu mi (8 cu km) of material were hurled into the air (1956); the peak of Tristan da Cunha, whose eruption caused the entire settlement to be evacuated (1961); Agung, in Bali, which killed 1,100 people (1963); Mt. St. Helens in Washington, which exploded with an energy equivalent to 10 million tons of TNT, killing 35, with 25 missing (1980); El Chichon in Mexico, which expelled about 500 million tons of ash and gas (1982); and Mt. Pinatubo in the Philippines, which killed over 500 people and ejected over 2 cu mi (8 cu km) of material (1991). Other notable volcanoes are Cotopaxi and Chimborazo (Ecuador), Iztaccíhuatl and Popocatépetl (Mexico), Lassen Peak and Katmai (United States), Etna (Sicily), and Hekla, Katla, and Laki (Iceland). Mauna Loa (Hawaii) is the world's largest active volcano, projecting 13,677 ft (4,170 m) above sea level and over 29,000 ft (8,850 m) above the ocean floor; from its base below sea level to its summit, Mauna Loa is taller than Mt. Everest. In 1963 the birth of the volcanic island Surtsey near Iceland was observed. In November of that year events began with a submarine eruption along the Mid-Atlantic Ridge. Eruption followed eruption until they ended in June, 1967, by which time the island stood 492 ft (150 m) above sea level and covered an area of almost 2 sq mi (3 sq km). The island has diminished in size since then due to erosion.

Earth..........

               From the perspective we get on Earth, our planet appears to be big and sturdy with an endless ocean of air. From space, astronauts often get the impression that the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the distinguishing Earth features are the blue waters, brown and green land masses and white clouds set against a black background.

Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times. 

Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation.Earth is the densest planet in the Solar System and the largest of the four terrestrial planets.

Many dream of traveling in space and viewing the wonders of the universe. In reality all of us are space travelers. Our spaceship is the planet Earth, traveling at the speed of 108,000 kilometers (67,000 miles) an hour.

Earth is the 3rd planet from the Sun at a distance of about 150 million kilometers (93.2 million miles). It takes 365.256 days for the Earth to travel around the Sun and 23.9345 hours for the Earth rotate a complete revolution. It has a diameter of 12,756 kilometers (7,973 miles), only a few hundred kilometers larger than that of Venus. Our atmosphere is composed of 78 percent nitrogen, 21 percent oxygen and 1 percent other constituents.

Earth is the only planet in the solar system known to harbor life. Our planet's rapid spin and molten nickel-iron core give rise to an extensive magnetic field, which, along with the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Earth's atmosphere protects us from meteors, most of which burn up before they can strike the surface.

Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans. The remaining 29% is landconsisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics.

Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphereand surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[ that ever lived on Earth are extinct. Estimates of the number of species on Earth today vary widely; most species have not been described. Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states.

Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus, and later Norse mythology included Jörð, a giantess often given as the mother of Thor.

Formation

The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago (Bya). By 4.54±0.04 Byathe primordial Earth had formed. The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides). According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 million years (Mys) to form. 

A subject of research is the formation of the Moon, some 4.53 Bya. A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth. In this view, the mass of Theia was approximately 10 percent of Earth, it hit Earth with a glancing blow and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth.

Geological history

Earth's atmosphere and oceans were formed by volcanic activity and outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets, and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity. By 3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. 

A crust formed when the molten outer layer of Earth cooled to form a solid. The two models that explain land mass propose either a steady growth to the present-day formsor, more likely, a rapid growth early in Earth history followed by a long-term steady continental area. Continents formed by plate tectonics, a process ultimately driven by the continuous loss of heat from Earth's interior. Over the period of hundreds of millions of years, the supercontinents have assembled and broken apart. Roughly 750 million years ago (Mya), one of the earliest known supercontinents, Rodinia, began to break apart. The continents later recombined to form Pannotia 600–540 Mya, then finally Pangaea, which also broke apart 180 Mya. 

The present pattern of ice ages began about 40 Mya and then intensified during the Pleistocene about 3 Mya. High-latitude regions have since undergone repeated cycles of glaciation and thaw, repeating about every 40,000–100,000 years. The last continental glaciation ended 10,000 years ago.

Origin Life and Evolution

Chemical reactions led to the first self-replicating molecules about four billion years ago. A half billion years later, the last common ancestor of all current life arose. The evolution of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant molecular oxygen 

2) accumulated in the atmosphere and due to interaction with ultraviolet solar radiation, formed a protective ozone layer 

3) in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the development of complex cells called eukaryotes. True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by the ozone layer, life colonized Earth's surface. Among the earliest fossil evidence for life is microbial mat fossils found in 3.48 billion-year-old sandstone in Western Australia, biogenic graphite found in 3.7 billion-year-old metasedimentary rocks in Western Greenland and remains of biotic material found in 4.1 billion-year-old rocks in Western Australia. The earliest direct evidence of life on Earth is contained in 3.45 billion-year-old Australian rocks showing fossils of microorganisms. 

During the Neoproterozoic, 750 to 580 Mya, much of Earth might have been covered in ice. This hypothesis has been termed "Snowball Earth", and it is of particular interest because it preceded the Cambrian explosion, when multicellular life forms significantly increased in complexity.Following the Cambrian explosion, 535 Mya, there have been five mass extinctions. The most recent such event was 66 Mya, when an asteroid impact triggered the extinction of the non-avian dinosaurs and other large reptiles, but spared some small animals such as mammals, which at the time resembled shrews. Mammalian life has diversified over the past 66 Mys, and several million years ago an African ape-like animal such as Orrorin tugenensis gained the ability to stand upright. This facilitated tool use and encouraged communication that provided the nutrition and stimulation needed for a larger brain, which led to the evolution of humans. The development of agriculture, and then civilization, led to humans having an influence on Earth and the nature and quantity of other life forms that continues to this day.

From our journeys into space, we have learned much about our home planet. The first American satellite, Explorer 1, discovered an intense radiation zone, now called the Van Allen radiation belts. This layer is formed from rapidly moving charged particles that are trapped by the Earth's magnetic field in a doughnut-shaped region surrounding the equator. Other findings from satellites show that our planet's magnetic field is distorted into a tear-drop shape by the solar wind. We also now know that our wispy upper atmosphere, once believed calm and uneventful, seethes with activity -- swelling by day and contracting by night. Affected by changes in solar activity, the upper atmosphere contributes to weather and climate on Earth.

Besides affecting Earth's weather, solar activity gives rise to a dramatic visual phenomenon in our atmosphere. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as the auroras or the northern and southern lights.

Nature-Definitions

             There are many definitions about nature.Nature is all the animals, plants, and other things in the world that are not made by people, and all the events and processes that are not caused by people.Nature, in the broadest sense, is the natural, physical, or material world or universe. Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic."Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena.

            Nature is a phenomenon including plants, animals, the landscape, the earth, the sea, the river, the ocean, the sky, the sun, the moon, the tree, the flower, the galaxy, the universe and the creatures; to others, it is human psychology, human thought, human nature including hunger, thirst, anger; while some others tend to believe it is everything that lies beyond the scope of our senses and perceptiveness

              The term "nature" may refer to living plants and animals, geological processes, weather, and physics, such as matter and energy. The term is often refers to the "natural environment" or wilderness—wild animals, rocks, forest, beaches, and in general areas that have not been substantially altered by humans, or which persist despite human intervention. For, example, manufactured objects and human interaction are generally not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of "nature" implies a distinction between natural and artificial elements of the Earth, with the artificial as that which has been brought into being by a human consciousness or a human mind.

                  The word nature is derived from the Latin word natura, or "essential qualities, innate disposition", and in ancient times, literally meant "birth".Natura is a Latin translation of the Greek word physis, which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord.

                The concept of nature as a whole,the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word by pre-Socratic philosophers, and has steadily gained currency ever since. This usage continued during the advent of modern scientific method in the last several centuries.

              Within the various uses of the word today, "nature" often refers to geology and wildlife. Nature can refer to the general realm of living plants and animals, and in some cases to the processes associated with inanimate objects–the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth. It is often taken to mean the "natural environment" or wilderness–wild animals, rocks, forest, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. For example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human consciousness or a human mind. Depending on the particular context, the term "natural" might also be distinguished from the unnatural or the supernatural.

MOUNTAINS.....

           

             Mountains are a common sight on this planet. They make up one-fifth of the world's landscape, and provide homes to at least one-tenth of the world's people. Furthermore, 2 billion people depend on mountain ecosystems for most of their food, hydroelectricity, timber, and minerals. About 80 per cent of our planet's fresh water originates in the mountains. Since about half of the world's people are reliant upon mountains for fresh water, and in this time of increasing water scarcity, it is becoming increasingly important to protect the mountain biome. All mountain ecosystems have one major characteristic in common--rapid changes in altitude, climate, soil, and vegetation over very short distances. Mountain ecosystems sport a high range of biodiversity, and are also a home to many of our planet's ethnic minorities. These cultures are sometimes 'protected' due to the challenging environment to produce a living, but others are not. More and more these indigenous people are being kicked out of their homes due to population and commercial growth, logging, and mining. An example of the mountain's wide variety of organisms can be seen in California's Sierra Nevada range

                 A mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. Mountains are formed through tectonic forces or volcanism. These forces can locally raise the surface of the earth by over 10,000 feet (3,000 m). Mountains erode slowly through the action of rivers, weather conditions, and glaciers. A few mountains are isolated summits, but most occur in huge mountain ranges.High elevations on mountains produce colder climates than at sea level. These colder climates strongly affect the ecosystem of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction and recreation, such as mountain climbing.

                     The highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8,848 m (29,029 ft) above mean sea level. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21,171 m (69,459 ft).The world's mountains provide a home to several thousand different ethnic groups. The mountain people, which mainly consist of indigenous people, ethnic minorities, and refugees, have been able to cope with this harsh environment of the mountain ecosystem. They live as nomads, hunters, foragers, traders, small farmers, loggers, and miners, etc. Most mountain people all share one attribute -- material poverty. However, what they lack in material wealth they make up in community life. They have been able to live off the land without widespread destruction and deforestation. Plant and animal species have been preserved by these people.

                    For instance, in India's Garhwal Himalaya, local women were recently successful in identifying over 145 species of plants that had been destroyed by commercial logging and limestone mining; the national foresters could only list 25! Unfortunately, these cultures have been subjected to discrimination and other violations of human rights. They have been called degrading words such as 'hillbillies' (United States), 'oberwalder' (Austria), 'kohestani' (Afghanistan), and 'bhotias' (India). We need to learn not only how to preserve the biological diversity in the mountains, but the cultural diversity also.The Himalayan Yew, a slow-growing conifer, is currently on the World Wildlife Fund's list of the ten most endangered animals. This plant can be found throughout Bhutan, Afghanistan, India, Nepal, Burma, and maybe China. Taxol, which is promising to be a drug which can help cure cancer, is present in both the Pacific and Himalayan varieties. Found in the world's highest mountain range, the Himalayan Yew is extremely rare because of heavy deforestation and harvesting for Taxol extraction, without replanting.

                    There are three main types of mountains: volcanic, fold, and block. All three types are formed from plate tectonics: when portions of the Earth's crust move, crumple, and dive. Compressional forces, isostatic uplift and intrusion of igneous matter forces surface rock upward, creating a landform higher than the surrounding features. The height of the feature makes it either a hill or, if higher and steeper, a mountain. Major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity.

Volcanoes

            Volcanoes are formed when a plate is pushed below another plate, or at a mid-ocean ridge or hotspot. The downward moving plate melts, and forms magma that reaches the surface. When the magma reaches the surface, it often builds a volcanic mountain, such as a shield volcano or a stratovolcano.

             Examples of volcanoes include Mount Fuji in Japan and Mount Pinatubo in the Philippines. The magma does not have to reach the surface in order to create a mountain: magma that solidifies below ground can still form dome mountains, such as Navajo Mountain in the United States.

Fold mountains

                  Fold mountains occur when two plates collide: the continental rocks then crumple together and the surface rises.Since the less dense continental crust "floats" on the denser mantle rocks beneath, the weight of any crustal material forced upward to form hills, plateaus or mountains must be balanced by the buoyancy force of a much greater volume forced downward into the mantle. 

                   Thus the continental crust is normally much thicker under mountains, compared to lower lying areas. Rock can fold either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines: in asymmetric folding there may also be recumbent and overturned folds. The Jura Mountains are an example of fold mountains.

Block mountains

                  Block mountains are caused by faults in the crust: a seam where rocks can move past each other. When rocks on one side of a fault rise relative to the other, it can form a mountain.The uplifted blocks are block mountains or horsts. The intervening dropped blocks are termed graben: these can be small or form extensive rift valley systems. 

             This form of landscape can be seen in East Africa, the Vosges, the Basin and Range province of Western North America and the Rhine valley. These areas often occur when the regional stress is extensional and the crust is thinned.

                 Commercial industries, especially large mines and hydropower projects, cause exceptional damage in mountains. This is because many companies are ignorant of the fragility of the ecosystems and rights of local communities. The U.N. Food and Agriculture Organization (FAO) discovered that during the past decade, tropical mountain forests have had both the fastest rates of both annual population growth and deforestation. Somehow, we need to come up with a way to find a compromise between preserving the cultural and biological diversity in mountains, and using them as a valuable resource. After all, if the mountains are exploited until they run dry, there will be no more resources for future generations. Currently, only 8 per cent of all mountains are protected in some form. If our world's highest mountains are able to inspire the greatest of mountain climbers to accomplish great feats, we should provide no lesser commitment to preserving the fragile ecosystems and endangered cultures which lie within them.

Rain forest.............

Rain forest.............

                 
                   Rain-forests are very dense, hot and humid forests and are home to millions of the earth’s plants and animals.  More species are found in rain-forests than any other habitat in the world.The word rain forest was first used at the end of the 19th Century to describe forests that grow in constantly wet conditions. Today, scientists define rain forests as forests that receive more than 2,000 mm of rain evenly spread throughout the year. Rain forests are the Earth's oldest living ecosystems. They are so amazing and beautiful.These incredible places cover only 6 %of the Earth's surface but yet they contain MORE THAN 1/2 of the world's plant and animal species!.

               A Rain-forest can be described as a tall, dense jungle.  The reason it is called a "rain" forest is because of the high amount of rainfall it gets per year.  The climate of a rain forest is very hot and humid so the animals and plants that exist there must learn to adapt to this climate. Rain-forests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm (68-78 inches). The monsoon trough, alternatively known as the intertropical convergence zone, plays a significant role in creating the climatic conditions necessary for the Earth's tropical rain-forests.

    Around 40% to 75% of all biotic species are indigenous to the rainforests. It has been estimated that there may be many millions of species of plants, insects and microorganisms still undiscovered in tropical rainforests. Tropical rainforests have been called the "jewels of the Earth" and the "world's largest pharmacy", because over one quarter of natural medicines have been discovered there. Rainforests are also responsible for 28% of the world's oxygen turnover, sometimes misnamed oxygen production,processing it through photosynthesis from carbon dioxide and consuming it through respiration.

                  The undergrowth in a rainforest is restricted in many areas by the poor penetration of sunlight to ground level. This makes it easy to walk through undisturbed, mature rainforest. If the leaf canopy is destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth of vines, shrubs and small trees, called a jungle. There are two types of rainforest, tropical rainforest and temperate rainforest.

                  There are actually two types of rainforest. Tropical and Temperate. When most people refer to rainforests they are talking about tropical rainforests.

Tropical

                   Tropical rainforests are found around the Equator. There is very little variation between the seasons. Can you think of a reason why? They have an even distribution of rainfall annually and are warm and hot all year round.

                Tropical rainforests are characterized in two words: warm and wet. Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year. Average annual rainfall is no less than 168 cm (66 in) and can exceed 1,000 cm (390 in) although it typically lies between 175 cm (69 in) and 200 cm (79 in).

                 Many of the world's rainforests are associated with the location of the monsoon trough, also known as the intertropical convergence zone. Tropical rainforests are rainforests in the tropics, found in the equatorial zone (between the Tropic of Cancer and Tropic of Capricorn). Tropical rainforest is present in Southeast Asia (from Myanmar (Burma) to Philippines, Malaysia, Indonesia, Papua New Guinea and northeastern Australia), Sri Lanka, sub-Saharan Africa from Cameroon to the Congo (Congo Rainforest), South America (e.g. the Amazon Rainforest), Central America (e.g. Bosawás, southern Yucatán Peninsula-El Peten-Belize-Calakmul), and on many of the Pacific Islands (such as Hawaiʻi). Tropical rainforests have been called the "Earth's lungs", although it is now known that rainforests contribute little net oxygen addition to the atmosphere through photosynthesis.

Temperate

                   Temperate rainforests are found further away from the equator. They have two seasons: a wet season and a dry season. The temperature varies much more than a tropical rainforest.

                   Temperate forests cover a large part of the globe, but temperate rainforests only occur in few regions around the world. Temperate rainforests are rainforests in temperate regions. 

                   They occur in North America (in the Pacific Northwest, the British Columbia Coast and in the inland rainforest of the Rocky Mountain Trench east of Prince George), in Europe (parts of the British Isles such as the coastal areas of Ireland and Scotland, southern Norway, parts of the western Balkans along the Adriatic coast, as well as in the North West of Spainand coastal areas of the eastern Black Sea, including Georgia and coastal Turkey), in East Asia (in southern China, Taiwan, much ofJapan and Korea, and on Sakhalin Island and the adjacent Russian Far East coast), in South America (southern Chile) and also inAustralia and New Zealand.

More Rainforest Facts!

• The Amazon Rainforest is the largest rainforest in the world, It covers an area of about 3 million square miles – that’s about 60 times bigger than the whole of England!

• Although they cover less than 2 percent of the Earth’s total surface area, the world’s rainforests are estimated to be home to half of the Earth’s plants and animals.

• Rainforests are the “lungs of our planet”. It is estimated that more than 20 percent of Earth’s oxygen is produced in the Amazon Rainforest.

• Because there is so much sunlight, heat and water – trees have the resources to grow to tremendous heights, and they live for hundreds, even thousands, of years.

Rain...........Rain.........Rain.........

                 

Rain...........Rain.........Rain.........

                  Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the planet. It provides suitable conditions for many types of ecosystem, as well as water for hydroelectric power plants and crop irrigation.The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts.

                  If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.

                  The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics.[citation needed] Antarctica is the driest continent. The globally averaged annual precipitation over land is 715 millimetres (28.1 in), but over the whole Earth is it much higher at 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall is measured using rain gauges. Rainfall amounts can be estimated by weather radar.
Rain is also known or suspected on other planets, where it may be composed of methane, neon, sulfuric acid or even iron rather than water.

Water-saturated air

             Air contains water vapor and the amount of water in a given mass of dry air, known as the mixing ratio, is measured in grams of water per kilogram of dry air (g/kg). The amount of moisture in air is also commonly reported as relative humidity; which is the percentage of the total water vapor air can hold at a particular air temperature. How much water vapor a parcel of air can contain before it becomes saturated (100% relative humidity) and forms into a cloud (a group of visible and tiny water and ice particles suspended above the Earth's surface) depends on its temperature. Warmer air can contain more water vapor than cooler air before becoming saturated. Therefore, one way to saturate a parcel of air is to cool it. The dew point is the temperature to which a parcel must be cooled in order to become saturated.

                There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, and evaporative cooling. Adiabatic cooling occurs when air rises and expands. The air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain (orographic lift). Conductive cooling occurs when the air comes into contact with a colder surface,usually by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath.Evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation.

              The main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet land,transpiration from plants, cool or dry air moving over warmer water, and lifting air over mountains. Water vapor normally begins to condense on condensation nuclei such as dust, ice, and salt in order to form clouds. Elevated portions of weather fronts (which are three-dimensional in nature) force broad areas of upward motion within the Earth's atmosphere which form clouds decks such as altostratus or cirrostratus. Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can also form due to the lifting of advection fog during breezy conditions.

Coalescence

                 Coalescence occurs when water droplets fuse to create larger water droplets, or when water droplets freeze onto an ice crystal, which is known as the Bergeron process. Air resistance typically causes the water droplets in a cloud to remain stationary. When air turbulence occurs, water droplets collide, producing larger droplets. As these larger water droplets descend, coalescence continues, so that drops become heavy enough to overcome air resistance and fall as rain. Coalescence generally happens most often in clouds above freezing, and is also known as the warm rain process.In clouds below freezing, when ice crystals gain enough mass they begin to fall. This generally requires more mass than coalescence when occurring between the crystal and neighboring water droplets. This process is temperature dependent, as supercooled water droplets only exist in a cloud that is below freezing. In addition, because of the great temperature difference between cloud and ground level, these ice crystals may melt as they fall and become rain.

                

                  

                 Raindrops have sizes ranging from 0.1 to 9 millimetres (0.0039 to 0.35 in) mean diameter, above which they tend to break up. Smaller drops are called cloud droplets, and their shape is spherical. As a raindrop increases in size, its shape becomes more oblate, with its largest cross-section facing the oncoming airflow. Large rain drops become increasingly flattened on the bottom, like hamburger buns; very large ones are shaped like parachutes.Contrary to popular belief, their shape does not resemble a teardrop. The biggest raindrops on Earth were recorded over Brazil and the Marshall Islands in 2004 — some of them were as large as 10 millimetres (0.39 in). The large size is explained by condensation on large smoke particles or by collisions between drops in small regions with particularly high content of liquid water. 

                 Intensity and duration of rainfall are usually inversely related, i.e., high intensity storms are likely to be of short duration and low intensity storms can have a long duration.Rain drops associated with melting hail tend to be larger than other rain drops. Raindrops impact at their terminal velocity, which is greater for larger drops due to their larger mass to drag ratio. At sea level and without wind, 0.5 millimetres (0.020 in) drizzle impacts at 2 metres per second (4.5 mph) (2 m/s or 6.6 ft/s), while large 5 millimetres (0.20 in) drops impact at around 9 metres per second (20 mph) (9 m/s or 30 ft/s). The sound of raindrops hitting water is caused by bubbles of air oscillating underwater. The METAR code for rain is RA, while the coding for rain showers is SHRA.

Plant Roots

Roots are the principal water-absorbing organs of a plant. They are present on essentially all vascular plants, although roots are never formed on the primitive-looking whisk fern (Psilotum) and its closest relatives (Order Psilotales), on Wolfiella (the tiniest duckweed), and on the plant body of certain atmospheric epiphytes, such as Spanish moss (Tillandsia). In fact, a root, by definition, must have vascular tissues, i.e., water conduits in xylem and sugar conduits in phloem, arranged in a particular way ("exarch"). Much thinner, threadlike rhizoids (means "root-like") are present on the nonvascular plants, such as mosses and liverworts, and on gametophytes of vascular plants without seeds, such as ferns, horsetails, and club mosses. Rhizoids also absorb water but totally lack vascular tissues.

The first root that comes from a plant is called the radicle. The four major functions of roots are 1) absorption of water and inorganic nutrients, 2) anchoring of the plant body to the ground, and supporting it, 3) storage of food and nutrients, 4) vegetative reproduction. Roots may be assisted in their function by other organisms living in the substrate. Many plants, including the majority of vascular plants and even the free-living gamatophytes, are involved in symbiotic relationships with fungi, called mycorrhizae.

Particular soil fungi grow either on the outside or on the inside of a root. This mycorrhizal association improves water absorption and the uptake of certain minerals from the soil. Certain genera of plants have roots that are inoculated with colonies of nitrogen-fixing microorganisms, especially legumes and their associated nitrogen-fixing bacteria (rhizobial bacteria). Living in tumor-like root nodules, nitrogen-fixing bacteria are able to convert atmosphere nitrogen gas to ammonia, under anaerobic conditions produced by the plant cells, and then use this fixed nitrogen to make amino acids. So, it this regard, root physiology may be involved in a very special way to deliver nutrients to the shoot.

TYPES OF ROOTS

A true root system consists of a primary root and secondary roots.

There are several possible fates of the primary root. In gymnosperms and dicotyledons, the primary root commonly grows to become a thick central root, the taproot, which may or may not have thick lateral roots (branches). This structural organization is frequently termed a taproot system, although in many old woody plants there may be many roots that are essentially the same diameter. The easiest designation of taproot is for something like a carrot (Daucus carota), where the lateral (secondary) roots are very thin, so that plant indeed has a single, thick central root. What may appear to be a taproot can also include enlarged portions of the hypocotyl (of the seedling) or even tissues of the lower stem.

 In monocotyledons, the radicle is very short-lived, and before it dies other adventitious roots have already originated from shoot or mesocotyl tissue to become the new root system, called a fibrous root system. Fibrous roots are typically thought of as slender, often with few or no lateral roots. However, many monocotyledons have below-ground adventitious roots that are thicker than a pencil, and in some the fibrous roots above-ground, such as the prop or stilt roots of screwpines (Pandanus) and certain palms (Family Arecaceae), can be as thick as an arm.

Adventitious roots are the ones that form from shoot tissues, not from another (parent) root. Most commonly, adventitious roots arise out of stems, originating via cell divisions of the stem cortex or less often from axillary buds hidden in the bark. In some plants leaves can also be encouraged to form adventitious roots. The field of horticulture is based in large part on cloning plants from cuttings of stems or leaves that form adventitious roots. [More examples: adventitious roots of a palm; of a Canary Island date palm; specialized adventitious roots of an epiphytic orchid; of an aquatic plant that has unattached roots in moving water] 

Certain "root crops" that botanically are below-ground shoots, such as tubers, bulbs, rhizomes, and corms, form adventitious roots when planted in soil. Vegetative reproduction (apomixis) of cacti and other succulent plants is also achieved largely by rooting either stems or leaves using methods to stimulate adventitious root formation.

Specialized roots

The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions described in the introduction.

Aerating roots (or knee root or knee or pneumatophores or Cypress knee): roots rising above the ground, especially above water such as in some mangrove genera (Avicennia, Sonneratia). In some plants like Avicennia the erect roots have a large number of breathing pores for exchange of gases.

Aerial roots: roots entirely above the ground, such as in ivy (Hedera) or in epiphytic orchids. They function as prop roots, as in maize or anchor roots or as the trunk in strangler fig.

ontractile roots: they pull bulbs or corms of monocots, such as hyacinth and lily, and some taproots, such as dandelion, deeper in the soil through expanding radially and contracting longitudinally. They have a wrinkled surface.

Coarse roots: Roots that have undergone secondary thickening and have a woody structure. These roots have some ability to absorb water and nutrients, but their main function is transport and to provide a structure to connect the smaller diameter, fine roots to the rest of the plant.

Fine roots: Primary roots usually <2 mm diameter that have the function of water and nutrient uptake. They are often heavily branched and support mycorrhizas. These roots may be short lived, but are replaced by the plant in an ongoing process of root 'turnover'.

Haustorial roots: roots of parasitic plants that can absorb water and nutrients from another plant, such as in mistletoe (Viscum album) and dodder.

Propagative roots: roots that form adventitious buds that develop into aboveground shoots, termed suckers, which form new plants, as in Canada thistle, cherry and many others.

Proteoid roots or cluster roots: dense clusters of rootlets of limited growth that develop under low phosphate or low iron conditions in Proteaceae and some plants from the following families Betulaceae, Casuarinaceae, Elaeagnaceae, Moraceae, Fabaceae and Myricaceae.

Stilt roots: these are adventitious support roots, common among mangroves. They grow down from lateral branches, branching in the soil.

Storage roots: these roots are modified for storage of food or water, such as carrots and beets. They include some taproots and tuberous roots.

Structural roots: large roots that have undergone considerable secondary thickening and provide mechanical support to woody plants and trees.

Surface roots: These proliferate close below the soil surface, exploiting water and easily available nutrients. Where conditions are close to optimum in the surface layers of soil, the growth of surface roots is encouraged and they commonly become the dominant roots.

Tuberous roots: A portion of a root swells for food or water storage, e.g. sweet potato. A type of storage root distinct from taproot.

Rooting Depths

The distribution of vascular plant roots within soil depends on plant form, the spatial and temporal availability of water and nutrients, and the physical properties of the soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands.

                                           

The deepest observed living root, at least 60 m below the ground surface, was observed during the excavation of an open-pit mine in Arizona, USA. Some roots can grow as deep as the tree is high. The majority of roots on most plants are however found relatively close to the surface where nutrient availability and aeration are more favourable for growth. Rooting depth may be physically restricted by rock or compacted soil close below the surface, or by anaerobic soil conditions.

Specialized Variations of Roots

Nodal roots: adventitious roots that form characteristically in rings from stem tissues around a node.

Prop or stilt roots: adventitious roots that develop on a trunk or lower branch that begin as aerial roots (another example; reaching for the water) but eventually grow into a substrate of some type; these roots in some cases seem to provide mechanical support, having either good compression or tensile properties to help support trees at their bases.

Buttress or tabular roots: vertically flattened roots that project out of the ground and lower trunk at the base of large trees. Models have suggested how these buttresses provide additional tensile forces to resist uprooting of large tropical trees.

Contractile roots: roots that become shortened in length (shrivel or shrink in length) and thereby draw the plant or plant part downward into the soil profile; many examples can be found among bulbous plants.

Pneumatophores: spongy, aerial roots of marsh or swamps, such as in mangal (mangroves), where roots are present in waterlogged soils and cannot obtain enough oxygen for maintaining healthy tissues. Here, pneumatophores are "breathing roots" that are emergent, and they have special air channels (lenticels) for gas exchange in the atmosphere (air enters at zones called "pneumathodes") and there is an internal pathway for getting O2 into the root and to supply submerged roots. The aerial loop of a mangrove root is sometimes called a "knee" or "peg root," but it is not clear that knees are necessarily breathing roots.

Caudex or lignotuber: a taproot that has fused with the stem may become woody. Lignotubers often occur in seasonally dry or fire-prone habitats, and the plants appear to use this strategy to recover from dormancy or fire.

Haustorial root: the root of particular parasitic plants that become cemented to the host axis via a sticky attachment disc before the root or sinker intrudes into the tissues of the host.

Strangling roots: the special name for roots of strangling figs (Ficus), which are primary hemiepiphytes that begin life as tropical epiphytes in trees and send down adventitious roots that become rooted in the soil. The roots surround the host trunk, eventually strangling the bark and killing the host tree.

Root tubers: swollen portions of a root that can have buds to produce new shoots; when broken off, these can grow into a new plant, so this is a form of cloning. In the older literature, these were sometimes referred to as fascicled roots.