The picture below shows how a hot balloon works. Summarize the information by selecting and reporting the main features.

The diagram depicts the construction of a hot

air

balloon

and its working mechanism.

Overall

, the construction consists of several parts, including the

envelope

, the skirt, the burner and the basket. It is

also

clear from the diagrams that the mechanism of a typical hot-

air

balloon

involves the upward circulation of hot

air

. As can be seen from the picture, the

balloon

,

also

called the

envelope

, is the largest part and

this

is a combination of multiple strips of fabric called gores. These gores are made of many nylon panels sewn together. The gores altogether form the

balloon

shape when fully inflated. On top of the

envelope

is a parachute valve, whose function is to open or close like a sealing flap.

This

allows hot

air

to escape in a controlled manner. The skirt is at the base of the

envelope

and the inside is made from a flame-resistant material to withstand the heat from the

burners

. The

burners

are fixed to a metal frame below the skirt and above the basket, which provides seats for passengers and the propane cylinders. These

burners

function as an engine, mixing propane with oxygen to generate hot

air

for the

balloon

. As for the working mechanism, hot

air

is fed into the

envelope

by the

burners

. The hot

air

inside is lighter than the cold

air

outside,

thus

providing a buoyant force to lift the entire structure.