Negative and positive words about our planet


Fabio Pacini 2008-05-01

We chose these words because they probably are the worst problems of our planet. We could have chosen many other words, but we think that, for example avalanches, aren’t kept in enough consideration.

Negative things


Deforestation:

international concern about the ecological consequences of continuing deforestation has been growing and was underscored by the United Nations Conference on the Environment and Development ("Earth Summit") held in Rio de Janeiro in 1992. International calls for conservation are based on the view that the Amazon basin is a global resource, one that serves as a control mechanism for the world's climate and as a genetic repository for the future. The nations of the region, however, tend to look upon such calls as a challenge to "national sovereignty."

Tsunami:

also called SEISMIC SEA WAVE, OR TIDAL WAVE, catastrophic ocean wave, usually caused by a submarine earthquake occurring less than 50 km (30 miles) beneath the seafloor, with a magnitude greater than 6.5 on the Richter scale. Underwater or coastal landslides or volcanic eruptions also may cause a tsunami. The term tidal wave is more frequently used for such a wave, but it is a misnomer, for the wave has no connection with the tides.

Earthquake:

any sudden disturbance within the Earth manifested at the surface by a shaking of the ground. This shaking, which accounts for the destructiveness of an earthquake, is caused by the passage of elastic waves through the Earth's rocks. These seismic waves are produced when some form of stored energy, such as elastic strain, chemical energy, or gravitational energy, is released suddenly.
Few natural phenomena can wreak as much havoc as earthquakes. Over the centuries they have been responsible for millions of deaths and an incalculable amount of damage to property. While earthquakes have inspired dread and superstitious awe since ancient times, little was understood about them until the emergence of seismology at the beginning of the 20th century. Seismology, which involves the scientific study of all aspects of earthquakes, has yielded answers to such long-standing questions as why and how earthquakes occur. These matters are discussed in this article, as are the distribution, size, and effects of earthquakes.

Avalanche:

large mass of rock debris or snow that moves rapidly down a mountain slope, sweeping and grinding everything in its path. An avalanche begins when a mass of material overcomes frictional resistance of the sloping surface, often after its foundation is loosened by spring rains or is rapidly melted by a foehn (warm, dry wind). Vibrations caused by loud noises, such as artillery fire, thunder, or blasting, can start the mass in motion.
Large rock avalanches (rockfalls) have dammed rivers and buried towns. They are commonly composed of bedrock fragments a few centimetres (an inch or so) in diameter and include much soil and dust. Rock avalanches are thought to ride on a cushion of compressed air that allows them to travel long distances. A debris avalanche usually occurs in unconsolidated earth materials when weakened by moisture.
Some snow avalanches develop during heavy snowstorms and slide while the snow is still falling, but more often they occur after the snow has accumulated at a given site. One of the causes of snow avalanches is the slow formation of depth hoar (hexagonal cuplike ice crystals that begin to form at ground level) under the snowpack. Depth-hoar crystals develop in loose array from the evaporation of the original snow particles and the simultaneous vapour deposition of larger, denser ice crystals near the ground; thus a zone of weakness occurs within the snowpack near the ground, the particles of which act as a lubricant when the upper layers of the snow start sliding down the mountain.
The wet snow avalanche is perhaps the most dangerous because of its great weight, heavy texture, and tendency to solidify as soon as it stops moving. The dry type is also dangerous because its entraining of great amounts of air makes it act like a fluid; this kind of avalanche may flow up the opposite side of a narrow valley. Avalanches can carry a considerable amount of rock debris with the snow.

Ice melting:
because of the global overheating, ice caps are slowly melting, and it could be extremely dangerous in the future, because a total melting of ice caps would cause unimaginable floods and the death of some million people.

Positive things:

We chose these words because they are the things that make us proud of our planet.

Hydrogen:

Hydrogen has been used as a primary rocket fuel for combustion with oxygen or fluorine and is favoured as a propellant for nuclear-powered rockets and space vehicles. Another increasing use of hydrogen is in the direct reduction of iron ores to metallic iron and in the reduction of the oxides of tungsten and molybdenum to the metals. A hydrogen (reducing) atmosphere is employed in the pouring of special castings, in the manufacture of magnesium, in the annealing of metals, and for the cooling of large electric motors. Hydrogen was once used for inflating lighter-than-air vessels, such as dirigibles and balloons, but now helium is generally used because it is nonflammable. The barrage balloons used in England during World War II, however, were filled with hydrogen. Liquid hydrogen is used in the laboratory to produce low temperatures.

Biodiversity:

the diversification of life through local adaptation of populations and speciation has created the tremendous biodiversity found on the Earth. In most regions a square kilometre (0.4 square mile) will harbour hundreds--in some places even thousands--of species. The interactions between these species create intricate webs of relationships as the organisms reciprocally evolve, adapting to one another and becoming specialized for their interactions.

The cycle of seasons:

Outside the tropics and the polar regions, the essential characteristic of the annual cycle is a temperature oscillation between a single maximum and a single minimum. This oscillation results from the annual variation in the angle at which the Sun's rays reach the Earth's surface and from the annual variation in the duration of sunlight on the Earth's surface each day. As the Earth moves in its orbit around the Sun, its axis maintains a nearly constant orientation in space, inclined about 66 33' to the orbital plane. During the six-month half of each orbit when the North Pole is inclined toward the Sun, a point in the Northern Hemisphere receives the Sun's rays at an angle closer to 90 than does a point in the Southern Hemisphere; this causes greater heating and more hours of daylight in the Northern Hemisphere than in the Southern Hemisphere. During the other six months, these conditions are reversed.

Rain forest:

Tropical rain forests play an important role in the exchange of gases between the biosphere and atmosphere. Significant amounts of nitrous oxide, carbon monoxide, and methane, for example, are released into the atmosphere from these forests. This metabolism is being changed by human activity. More than half of the carbon monoxide derived from tropical forests comes from their clearing and burning, which is reducing the size of such forests around the world.

Rainbow:

eries of concentric coloured arcs that may be seen when light from a distant source--most commonly the Sun--falls upon a collection of water drops--as in rain, spray, or fog. The rainbow is observed in the direction opposite to the Sun.
The coloured rays of the rainbow are caused by the refraction and internal reflection of light rays that enter the raindrop, each colour being bent through a slightly different angle. Hence, the composite colours of the incident light will be separated upon emerging from the drop.

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