GK
SOIL EROSION AND CONSERVATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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50 m height from the ground
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80 m height from the ground
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100 m height from the ground
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150 m height from the ground
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Detailed explanation-1: -Wind speed increases with increasing height above the ground, starting from zero due to the no-slip condition. Flow near the surface encounters obstacles that reduce the wind speed, and introduce random vertical and horizontal velocity components at right angles to the main direction of flow.
Detailed explanation-2: -In most instances, wind speeds increase up to the top of the planetary boundary (friction) layer generally located about 2, 000 ft. above ground level. Above this level, frictional drag becomes negligible.
Detailed explanation-3: -Since obstacles near the ground, such as building structures, plants and etc., disrupt air flow, causing larger frictional force, air flow near the ground is hence slower. On the contrary, there is less friction at higher place which is more exposed. The air flows faster and hence stronger winds (Figure 1).