Since the Martian atmosphere is only 1/100th of the Earth's atmosphere, how does the wind blow hard enough to create sandstorms? How does atmospheric density effect weather (wind, CO2 snow fall, rock erosion)?

How often do rovers experience sand storms? If so, does this damage the rover's instruments?

Would a burrowing rover be of value to protect itself from the Martian sandstorms?

Do martian sandstorms block out the sun as they do on earth?