Where do dust devils start?

Answer 1

Dust devils form when the sun heats the ground to very high temperatures, creating an unusually hot layer of air at ground level. This hot air will naturally tend to rise. As the air rises, new air moves in to replace it. If there is an eddy of air in the area, it can get caught up in this. As rotating air moves inward, it speed up, creating a relatively rapidly spinning column of air. The rising air lifts up dust, making the vortex visible.

Answer 2

Dust storms are caused by a number of factors:

• Prolonged drought - lack of rain to settle the soil, and to promote plant growth, which in turn helps keep the soil in place.
• Deforestation, leaving the ground open and exposed.
• Excessive heat and weather conditions, which can lead to the raising up of high winds.
• Over-farming and over-grazing.

Answer 3

Mostly deserts

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Unlike tornadoes which start in the clouds and come down to the ground, Dust Devils or whirlwinds are caused when a layer of air just above the ground is heated by the ground and therefore becomes less dense (lighter) than the air above it. This hot air starts to rise and starts to drag in the hot air layer around it and the base of the rising thermal forms the twisting Dust Devil.

Dust Devils therfore form on days when there is no wind (which would mix up the air over the land) in places where the land is flattish and the heating by the sun is strong

Answer 4

As the force of wind passing over loosely held particles increases, the smallest particles first start to vibrate, then to saltate ("leap"), and to travel in suspension and to land again possibly bouncing or causing other particles to move. At wind speeds above that which causes the smallest to suspend, there will be a population of dust grains moving by a range of mechanisms: suspension, saltation and creep.[1]

Particles become loosely held mainly due to drought or arid conditions, and wind has varied causes. Gust fronts may be produced by the outflow of rain-cooled air from an intense thunderstorm, or they may represent a dry cold front, that is, a cold front that is moving into a dry air mass and is producing no precipitation. This is the type of dust storm which was common during the Dustbowl years in the U.S. Following the passage of a dry cold front, convective instability resulting from cooler air riding over heated ground can maintain the dust storm initiated at the front. In desert areas, dust and sand storms are most commonly caused by either thunderstorm outflows, or by strong pressure gradients which cause an increase in wind velocity over a wide area. The vertical extent of the dust or sand that is raised is largely determined by the stability of the atmosphere above the ground as well as by the weight of the particulates. In some cases, dust and sand may be confined to a relatively shallow layer by a low-lying temperature inversion. In other instances, dust (but not sand) may be lifted as high as 20,000 feet (6,100 m) high.

Drought and wind contribute to the emergence of dust storms, as do poor farming and grazing practices by exposing the dust and sand to the wind.

Answer 5

Dust storms form over land which is dry and which usually contains a lot of loose topsoil.

Dust storms are caused by a number of factors:

• Prolonged drought - lack of rain to settle the soil, and to promote plant growth, which in turn helps keep the soil in place.
• Deforestation, leaving the ground open and exposed.
• Excessive heat and weather conditions, which can lead to the raising up of high winds.
• Over-farming and over-grazing.

Answer 6

Dust devil formation begins when the sun heats a patch of ground, which in turn heats the layer of air just above it to very high temperatures. This hot air will naturally tend to rise. As the wind blows across buildings, plants, and uneven terrain it develops weak eddies. If one of the eddies gets caught in the rising, hot air it can tighten and intensify, forming a vortex of fairly strong winds that we call a dust devil.

Answer 7

THe hot dry days of summer.