what causes weather

Weather is the physical condition of the atmosphere at the particular time.It includes temperature,air pressure and water content.

Weather is produced when air moves from place to place.This moving air is known wind.Wind  are form when the cooler air moves in to replace the rising warm air.Warm air usually less than that cool air;therefore,it's creates low air pressure.Cool air is more dense and creates air pressure.

Usually we have fine weather when the air pressure is high and there are clouds,rain and snow when the air pressure drops.