The picture illustrates the working of a hot air balloon.
A hot air balloon consists of 3 main components: the balloon, burner system, and basket. Primarily this system works on the principle of density, as hot air is lighter than cold air. Furthermore, the balloon acts as a container of hot air, which is provided by the burner system. Both components work together in order to lift the basket.
The balloon is made up of several smaller parts: such as parachute valve, gores, panels, skirt and rope. The parachute valve acts as a self-sealing flap that lets hot air to escape in a controlled manner. Gores, panels, and skirt make up the sturture of the balloon, while the rope is used to connect the balloon and basket. The burner is placed on top of the basket paired with a propane cylinder.
Firstly, the propane and air mix together resulting in combustion which produces hot air. Secondly, the hot air fills the balloon causing the basket to lift. The elevation of the hot air balloon is controlled by the parachute valve in which releasing hot air allows the elevation to drop and vice-versa.