The sand storms are common in regions very droughts and that they present the ground unprovided of vegetation, as for andxemplo, the deserts, the region north of China and the region of Great Plains in U.S.A.
The intensity of the winds can vary in accordance with the region very, causing since what we can call dust survey until sand storms properly said with the 100 winds that can pass of km/h.
Invariably the storms or survey of dust intervene with the visibility in greater or minor degree. When the visibility if reduces for 1,5 km the 10 km says that it has dust formation, and when this is reduced to less than 1,5 km says that it has formation of dense dust or storm.
When the moistness of air reaches a low platform very in regions that already possess dry climate e, therefore has the ground covered by an arenaceous layer, occurs the particle suspension of the ground that can be carried the kilometers from distance for the winds. When it has only fall of the relative moistness of air, but it exists stability, the dust tends to remain close to the ground.
But, when great instability exists raises occurs it of the dust mass being able to occur of two forms: without the presence of significant horizontal winds: thus, the dust simply goes up and is spread, forming a layer similar to mist and that it can hide the sun total; or, strong winds can occur that load the dust causing the storms. When this occurs, the dust, or sand, forms a species of wall that goes advancing led for the winds.
After occurring the storm or it raises of dust, this is deposited. If to occur some precipitation form (snow, hail or rain), the dust particles can be loaded for these causing a precipitation muddy or colored by the particles that before were suspended. But, the precipitation of the which had dust can also occur, simply, when ceasing the wind. When it happens in such a way, the dust simply falls depositing tons of dust, or sand.