近日，北方多地出现扬沙或浮尘天气。北京、河北、山西、内蒙古、甘肃等地出现沙尘暴，局地出现能见度不足500米的强沙尘暴。沙尘暴在世界各地都普遍存在，它们由大量尘土组成，这些尘土被强风从干燥的地面吹向空中，从而形成沙尘暴天气。只要是沙尘暴都可能是大范围，且强烈的，通常也不会持续很长时间，但这会对人类呼吸造成影响，因此为沙尘暴到来之前做准备很重要，这样我们就可以轻松地避免不必要的伤害。
If you live in parts of the Southwest or Southern California this is probably a familiar sight: a massive wall of dust swallowing up everything in its path, like something out of a science fiction movie.
This is a dust storm.
So, what is a dust storm?
What's a haboob?
And what the heck causes those massive clouds of blowing desert sand anyway?
Let's talk basics.
The National Weather Service says a dust storm is a severe weather condition with strong winds and dust-filled air over an extensive area.
Sometimes wind causes a minor dust storm that makes the air thick and hazy, but some storms are so intense that often there's a clearly defined wall of dust that can be seen from miles away.
This dust can sometimes turn blue sky to orange.
It's dramatic.
