question: What happens when sunlight shines on a solar balloon ?
answer: the air inside is heated and expands causing an upward buoyancy force
turker_answer: When sunlight shines on a solar balloon , the air inside is heated and expands , causing an upward buoyancy force .
rule-based: The air inside is heated and expands causing an upward buoyancy force happens when sunlight shines on a solar balloon .