Upside-down?

One morning, everyone in the world woke up upside-down.  And I'm not talking wrong-side-of-the-bed.  I'm talking seriously upside-down.  Rather than being on the ground, people walked on some sort of false ground in the air.  There was a definite boundary here.  Everything was on the same sphere, suspended several miles above the Earth's surface.  Mountain climbers suddenly found themselves without mountains, and thus without a job.  Runners rejoiced, for they no longer had to run hills.  Children laughed, and cried, and ran around as fast as their legs would carry them, admiring the strange sights and sensations.  Clouds floated through cities and dropped rain away from them.  The thin air was to blame for the deaths of millions of ill and elderly, and world population was suddenly not so much of a problem.  As the day wore on, though, people discovered a dilemma.  There was no food.  Sure, some larger households would be able to survive for weeks on their sizable pantries, but many of the less well-off would be starving within a few days.  By four that afternoon, NASA engineers and scientists had regrouped.  After a few futile hours of arguing over the cause of this strange mishap, they agreed that they would have to send well-equipped expeditions back to Earth to bring food back to the people.  Around ten pm, they called it quits for the night and agreed to meet again the next day to plan their excursions. 
The next morning, everyone woke up as usual, firmly planted on the Earth.  No one was ever sure whether it had been a dream.