Larry went home and attached this do-it-yourself flying kit to a lawn chair. Before inflating the balloons, he anchored the lawn chair to the bumper of his car. Larry knew full well that the balloons, once inflated with featherweight helium, would have great buoyancy and rise up and away if precautions weren't taken (to understand buoyancy, think of an inflated rubber duck playfully submerged in a bathtub of water and then released - it buoyantly bobs quickly to the surface). Once all 45 balloons were inflated and, with the still tethered lawn chair now about two feet off the ground, Larry climbed aboard to get a feel for the aircraft.
Convinced that his flying machine would take him 10 m (33 ft) or so above his back yard where he would hover the day away, Larry temporarily deplaned. Knowing that there wouldn't be any flight attendants or landing protocol, Larry proceeded to pack sandwiches, drinks and a loaded pellet gun for final descent, figuring he would land on his backyard runway by popping a few balloons and descending after losing buoyancy. With provisions and flight plan in hand, Larry again climbed aboard, tied himself securely to the lawn chair and severed the tether to his car's bumper.
Instead of drifting lazily skyward, the helium-ballooned craft rocketed toward the heavens, quickly reaching a chilly cruising altitude of about 3000 m (11000 ft). Floating two miles above Los Angeles, he decided not to start shooting balloons, fearing that his flying machine might become unbalanced and that his lawn chair cockpit might capsize. Frightened and cold, Larry drifted with the wind for more than 14 hours.
As if his situation couldn't get any worse, Larry then headed into the primary approach pattern for the Los Angeles International Airport, located on the coast west of the city. A pilot of a United Airlines flight first spotted Larry (now that must have been quite a sight!) and he immediately radioed the control tower that he and his crew had just observed some guy on a lawn chair with a gun.
As night began to fall and offshore winds began to blow Larry out to sea, a helicopter (which had been dispatched from the airport after radar confirmed a flying object over restricted airspace) closed in. After sizing up the increasingly perilous situation, the helicopter lowered a towing line, which Larry successfully snared. To make a long story short, Larry was rescued and then promptly arrested for violating restricted airspace.
Larry was lucky. Underestimating the great buoyancy of the armada of helium-filled balloons nearly cost him his life. Regular parcels of air can't rise like Larry's helium-filled balloons. For one thing, any tendency for parcels of air to rise in response to the vertical pressure gradient force (lower pressure aloft, higher pressure near the surface) is, on average, offset by gravity acting downward. Such a balance is called hydrostatic equilibrium. In the rough-and-tumble world of weather, the general state of hydrostatic equilibrium is doomed to be broken now and then. Indeed, large departures from hydrostatic balance can be observed on small spatial and small time scales: buoyant, balloon-like parcels of air can ascend quickly to the tropopause, helping to sustain tall thunderstorms that can threaten lives and property with lightning, strong gusts of wind, heavy rain, large hail and tornadoes. To aid in the forecasting of such storms, meteorologists continually assess the potential buoyancy of parcels of air, thereby gauging the "stability" of the atmosphere.