How do dust storms happen?

Answer 1

A dust storm is usually caused by the top layer of earth becoming very dry over time, usually from a drought. When the wind becomes heavy enough, it will pick up only the smallest particles of dirt, which resembles dust, and will carry them through the air.

Answer 2

the main thing is that the air has to rise fast and over a long distance. It happens mostly when the air is unstable, i.e. very cold air above warm one but it can also happen when e.g. warm and moist air is lifted into cold one by a mountain range. It is then called orographic thunderstorm.

A cumulonimbus is like a big chimney. At the bottom, there is a lot of warm and moist air. At the top, cold and dry one.

Now, what happens when air rises? It cools down by the adiabatic effect of a lesser pressure in altitude. Then, it stops rising because the temperature has become even with the surrounding one.

But when the moisture condense, the so-called wet adiabatic lapse rate is only half that of dry air.

It means that once in the cloud, the air keeps rising, never reaching a temperature equal to the surrounding air. And that keeps up until the top of the troposphere, at about 40,000 ft of altitude, there where the temperature starts to increase again with altitude: the stratosphere!

So, you can imagine how a chimney of 40,000 ft can generate much static electricity when all those molecules move up very fast.

Answer 3

How does a duststorm start? 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 4

Dust storms usually happen during a drought. (a dry period with barely any rain). When a strong enough wind comes along, it snatches up dust and dirt and creates a dust storm.