It’s caused because the sun heats the planet differently, and over vast areas. As a place warms up, the air expands, causing a pressure change. Wind is simple high pressure air moving towards a low pressure region to balance things out. The boundaries are not normally so definite that you could notice the effect you described.Simply, it is caused by sun because if no sun will there Then the no area will become hot, no air will rise, and no one will come to take the rising air’s placeHope it helps!!