 Answers Black objects absorb more sunlight, specifically infrared energy, than white ones, which reflect a lot of the light. This extra energy is transferred to the black bottle's air inside. As the air inside that bottle warms it expands, as its particles move faster and faster. Many force their way up into the balloon, which expands because of the pressure from air particles still coming up from below. White clothing reflects more light than black clothing, so less energy is absorbed and you won't feel as hot. This principle could in fact be used to help heat a house in winter if all the exterior walls and roof were painted black. The energy absorbed isn't negligible, but probably not enough to offset the aesthetics of living in a black house! Nevertheless, water can be warmed by running a black hose with many loops across your roof, and into a tank inside. |