(2011? Xiangcheng District Simulation) Xiao Ming’s family lives in a family courtyard facing the street in the city. The street faces north and south. Every spring when the southerly wind blows, the streets are littered with

Because the pressure of fluid is small where the flow velocity is high, and the pressure is strong where the flow velocity is low. Therefore, when leaves fluttering in the wind pass by the door, the leaves are used as a reference. The air flow on the side of the leaves facing the street is faster and the air pressure is smaller. The pressure difference causes the leaves to float into the courtyard.

So the answer is: in the courtyard; small.