Run of the mill?_其他_趣味英语-查字典英语网

Run of the mill?

Mars is no stranger to dust storms, but this one isn’t a run-of-the-mill tempest. It’s far more gargantuan. These global storms occur only once every 5.5 years or so, swallowing up the entire planet in a cloud of red.

The dust storms on Mars work largely the same as they do on Earth. You have high winds that roll across the surface and move small grains forward, on the order a few hundred microns in size. These grains bounce up into the air, and once they’re just a few centimeters up the increased turbulence takes them higher and higher. Take that situation and watch it cascade into something abhorrently larger, and you have yourself a dust storm—capable of launching dust up to 20 kilometers in the air, covering up large swaths of land.

“The trick on Mars,” says Don Banfield, a planetary scientist at Cornell University, “is that the air density is only about one percent of what it is on Earth, because Mars has a very low atmospheric pressure. The winds will have to be faster to move the particles on Mars around, but it will come off as more or less the same force.” Those winds during these storms top off at 60 miles per hour, but due to a lack of atmosphere, they’ll end up feeling like just a refreshing breeze.”

- Weather got you down? The entire planet of Mars is buried in a dust storm right now, PopSci.com, June 22, 2018.

About the author:

Zhang Xin is Trainer at chinadaily.com.cn. He has been with China Daily since 1988, when he graduated from Beijing Foreign Studies University. Write him at: zhangxin@chinadaily.com.cn, or raise a question for potential use in a future column.