A wind of a velocity of 5 m/s cannot carry with it sand grains whereas one blowing at a velocity of 5~8 m/s stirs up ripples on the surface of the sand sea.
英
美
- 每秒5米以下的风速是不会携带沙粒的。而每秒5至8米的风却会激起沙海的涟漪。