Morphology wind

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Deflation. Barre loose particles that lie on the soil surface and creeps or get up in the air. Deflation does wherever the ground surface is completely dry and covered with small loose particles from the weathering of rock or previously deposited by flowing water, ice or waves. The dry climate regions, virtually all land surface is exposed to the action of deflation, because the rocks and soil are exposed without any plant protection. The deflation process is selective. Therefore, in those places where there is a variety of media sizes, transported the fine while the laggards will thicknesses. The main form of erosion by deflation are small deep basin depressions called deflation. You may have a few meters to several kilometers in diameter, but its depth rarely exceed a few meters. They originate in regions of arid plain.

In some places the wind blows sand and dust on the rocks and soil, this process is called Wind abrasion or corrosion. The transport requires abrasion cutting elements in the wind.

Dust storms. It is caused when the ground surface has been totally deprived of its vegetation. A dust storm in the form of a dark cloud that extends several hundred feet high. The sites involved by the dust cloud are mired in a deep or total darkness. The visibility is reduced to a few meters to a fine powder that makes breathing difficult penetrates everywhere. It has been estimated that 1 km 3 of air suspension can travel about 900 tonnes of dust. The dust travels through the air at considerable distances. Some dust storms have come to travel 4000 km.

Sand Storm. It is a low cloud moving sand which reaches only a few feet in height (at most, 2 m) above ground. It consists of numerous particles of sand carried by strong wind gusts.

The reason that sand does not reach high altitudes is that each particle is moved by saltation movement. The move grain to describe a curved path and impact against the floor with considerable force but with a low angle. The impact causes the beans to bounce back and rise again.

Sand Dunes. A is any hill or dune sand accumulation due to wind action. The dunes can be active, or alive, when the absence of vegetation are constantly changing place under the action of wind currents. Are said to be inactive or fixed when the vegetation cover prevents the movement of them. The most common varieties Dunas:

Crescent Dune in or Barjan. Occurs isolated and plan view resembles a crescent with rounded tips. The Barjanes rest on horizontal surfaces and covered with pebbles. The sand begins accumulate downwind of an obstacle, such as a small hill, a rock or a bush. Once enough mass is accumulated sand begins to move in the direction of the wind and take the crescent-shaped feature. Due to this the barjanes tend grouped into alignments that move under the action of wind from a series of obstacles.

Transverse dunes. These are the places where the sand is so abundant that completely covers the floor, the dunes take the form of alignments as a wave if you separate entity as a channel hallways because their ridges tend to form a right angle with wind direction. The entire area is called the sea of sand, because that looks like a choppy ocean and immobilized by a sudden storm. Each of these alignments of sand has a sharp crest and are asymmetric, with the gentle slope next to the windward and leeward abruptly. Other alignments of transverse dunes lie parallel to the beaches that provide plenty of sand and have strong winds from the sea.

The Ergs. They consist of large accumulations of sand, often from the weathering of sandstone training infravacentes or near floodplains.

Parabolic dunes. Are those that have the concave ridge to windward, ie in the opposite direction of barjanes and transverse dunes.

A good example is representative of this family are the coastal dunes that form next to the beaches where large quantities of sand and the prevailing winds are blowing toward land. Deflation creates a saucer-shaped depression and sand builds up in a great lineup curve, seen from above, looks like a horseshoe. The slope of the dune that points to the ground is steep and is moving in while buried forests and kill trees.

Groups of Parabolic Dunes. They form in the plains and the arid plains, where vegetation is sparse and winds are strong, are developed in the lee of the depressions of deflection. The sand is retained by small shrubs and accumulate in low-rise wide alignments. These dunes are not steep and can remain relatively immobile.

Downs in Forks. The dune is moving in the direction of the wind and the ends of the parable is transformed into long, narrow parallel alignments. Its shape, plan view, resembles a hairpin, belong to the family of the dishes. You can see this type of dunes stabilized by vegetation.

Longitudinal Dunes. So named because they are aligned parallel to the direction of the wind. In the plateaus and plains desert, where sand is scarce but the winds are strong in a particular direction. Usually have a few meters, but can reach several kilometers in length. Are oriented parallel to prevailing winds, occupy large areas. These ridges have an average height of 10-15 meters are scattered between them of 2.4 km and its length is 40 to 80 km.

Sandbars. They are long alignments, growth and sharp ridge extending in the direction of the wind from a topographic barrier such as a hill sticking out of a desert plain.

Sword or Seif Dune. Alignment consists of a huge sandy ridge which goes up and down alternative resulting peaks and gorges and whose sides are formed by curved faces. The seifs can reach a few scenes of meters high and several kilometers long.

Duna Duna in Star or Pyramid. It's a big sand hill whose base appears as a many-pointed star to be seen in plants. The radial alignment of sand reach the center of the dune and culminating in sharp peaks of 150 meters or more in height from the base. The star dunes appear to remain fixed for centuries and can serve as guides for authentic travel in the desert.

Loess. Are deposits of wind-blown silt that has been deposited by dust storms which have occurred over many thousands of years. It generally has a uniform yellowish color and no visible stratification or some other color band. They tend to break along vertical cliffs wherever it is exposed by the action of a bulldozer running water or man. This type of break is possibly produced by the slight contraction experienced by the entire mass compacted to leave once it has been deposited by wind. The importance of loess in the possibilities of global agriculture can not easily be overestimated in the plains and loess plateaus have formed rich black soil particularly suitable for the cultivation of cereals also corn and wheat are grown widely.

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