فرآيندهاي بادي و تغييرات اشكال سطحي دردشت لوت

Aeolian Processes and Land/arms Changing in Dashte Lut (Loutplain)

Wind is also an important agent of erosion and sediments transport on the Dashte Lout. We need to see how surface winds are related to the circulation of the Atmosphere. The lout pattern of air flow (wind) is determined by the non uniform heat, cold and whet Land Surface. Coriolis effect distribution of topography (mountains , yardang and sand land). Winds speed achieved to at least 30 km/h and some times exceed 80 km/h. when wind speeds in dashte lout reach or exceed 80 km/h , coarse rock particles up to several centimeters in diameter can be lifted to heights of a meter or more. However wind speed rarely exceeds 50 km/h, a velocity described as a strong wind. In the dasht lout , in a strong wind the largest particles of sediment that can be suspend in the air stream are grains of sand. Larger particles settle out too quickly to remain aloft. At lower wind speed sands moves along close to the ground surface and only finer grains of dust move in suspension. If a wind blows across abed of sand the grains begin to move when the wind speed reaches about 4.5m/s (16km/h).The resulting forward rolling motion of the sand. with increasing wind speed, turbulence near the ground lifts moving sand grains into the air. This is the same Aeolian processes that changing land form in dashte lout. All moving along in dashte lout with the wind similar to those of a ping-pong ball bouncing across a table. Even in strong winds salting sand grains seldom rise far off the ground as shown by abrasion marks on utility poles and fence posts that are sand blasted up to a height of about a meter. Types of dunes based on form is: I-Barchan dune across on hard , fat desert floors in lout that wind direction and limited sand supply, height 0.5 to 40m. 2- Transverse dune , occurs inlout with abundant sand, conform by merging of individual barchans. 3- Linear dune. Along relatively straight , ridge-shaped dune in lout with limited sand supply and variable winds. 4- Star dune, a high more of 400m, tends to remain fixed in place in lout, where wind blows from all directions. 5- Parabolic dune, in lout parabolic dune shaped like a (U) or (V), with open end facing up wind.