Winds blow dry leaves down the pavement. How do winds blow?

Wind is the large-scale horizontal movement of air, and it is driven entirely by differences in atmospheric pressure between two places. Air always flows from a region of relatively higher pressure toward a region of relatively lower pressure, in the same way water flows from a higher level to a lower one, until the pressure difference is evened out. This pressure difference itself arises mainly from the sun heating different parts of the Earth's surface unequally.

In the scenario described, dry leaves are seen moving down the pavement because a mass of air is flowing over that stretch of ground. That flow exists because the air pressure at one point along the pavement is higher than at another point further down it, so air streams from the higher-pressure side toward the lower-pressure side, carrying the light, loose dry leaves along with it. This flow of air being felt and observed is exactly what we call wind.

This also rules out the reverse idea: air is pushed away from a high-pressure region, so it never spontaneously flows from a low-pressure region toward a high-pressure one — the pressure-gradient force only acts outward from the denser, higher-pressure air. It is also not a description of condensation, which is the phase change of water vapour into liquid droplets (as in cloud or dew formation) and has nothing to do with horizontal air movement. And the swaying or scattering of plants, dust, and small animals is simply an effect of wind blowing over them, not the definition of the wind itself. Movement of air from a higher-pressure area to a lower-pressure area is therefore the only physically accurate description of how wind blows.