Ballooning

Ballooning is the use of lighter-than-air balloons for flight, recreation, observation, or transport. It includes hot-air and gas balloons whose buoyancy supports people or instruments.

Buoyancy: Buoyancy is the upward force a fluid exerts on an immersed or floating object. A balloon rises when displaced air weighs more than the balloon and its contents.
Montgolfier brothers: Joseph-Michel and Jacques-Étienne Montgolfier were French inventors who developed practical hot-air balloons in the eighteenth century. Their experiments led to the first public demonstrations of hot-air balloon flight.
Weather balloon: A weather balloon is an uncrewed balloon carrying instruments that measure atmospheric conditions during ascent. It carries sensors through the atmosphere to collect weather data.
Airship: An airship is a powered lighter-than-air aircraft that can steer itself through the air. Unlike most balloons, airships use propulsion and aerodynamic control for directed travel.
Siege of Paris (1870–1871): The Siege of Paris was a German blockade of the French capital during the Franco-Prussian War. Balloons carried people and mail out of the besieged city.
Archimedes' principle: Archimedes' principle states that an immersed body experiences an upward force equal to the weight of displaced fluid. It quantifies the buoyant force that makes balloon flight possible.
Francesco Lana de Terzi: Francesco Lana de Terzi was an Italian Jesuit priest whose 1670 book proposed an evacuated-sphere airship. His design anticipated buoyant flight but could not be built with available materials.
Radiosonde: A radiosonde is a package of instruments that transmits measurements of atmospheric pressure, temperature, and humidity. Weather balloons lift radiosondes into the upper atmosphere.
Fixed-wing aircraft: A fixed-wing aircraft generates lift through airflow over stationary wings. It depends on forward motion rather than buoyancy to remain airborne.
Andrée's Arctic balloon expedition: Andrée's Arctic balloon expedition was an 1897 Swedish attempt to reach the North Pole by hydrogen balloon. Its tragic failure exposed the hazards of long-distance balloon exploration.

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