Sentence:  Like most human activities, ballooning has sponsored heroes and hucksters and a good deal in between. For every dedicated scientist patiently recording atmospheric pressure and wind speed while shivering at high altitudes, there is a carnival barker with a bevy of pretty girls willing to dangle from a basket or parachute down to <WSD>earth</WSD>. 
Meaning of the word marked with <WSD> tags:  The ground, land (as opposed to the sky or sea).