CO2 in the air increases measurably at night when plants shut down photosynthesis for the day, and then hits a low in the sunny afternoon as the plants go full steam turning CO2 into vegetables.

• 到了晚上，植物都停止了光合作用，二氧化碳含量显著上升，在晴日的下午则会因为植物开足马力将二氧化碳转化为营养物质而达到低值。