A dust / sand storm is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dust from a dry surface.
As the force of wind passing over loosely held particles increases, particles of sand first start to vibrate, then to saltate ("leap"). As they repeatedly strike the ground, they loosen and break off smaller particles of dust which then begin to travel in suspension. 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
Signs are usually erected with a purpose, to inform the population of something relevant and important.
Sometimes however, signs are erected which seem to have no point at all!
The fantastic info-graphic below from Cheese9 tells us what the odds really are of some well known, sought after or even feared events occurring.
What are the odds of dying in a plane crash or being hit by falling plane parts?
What chances do you have of becoming president or being an astronaut
Cracked.com wrote a very informative article about performing tricks that appear incredibly dangerous.
As you will see if you click on the link above, there are various
death-defying stunts that are secretly easy to do