Fig. 15

(a) The number of microplastic particles transitioning from the oceans into the atmosphere per km² per hour depending on rain rate for \(1 \frac {\mathrm {m}}{\mathrm {s}}\) vertical updraft velocity. The contribution of different raindrop sizes to particle transport is illustrated by the colored areas. With rising rain rate, the number of transitioning particles increases as both the number of raindrops and the fraction of larger raindrops become larger. (b) Different vertical updraft velocity strongly affects the number of transitioning particles. For less than \(0.5 \frac {\mathrm {m}}{\mathrm {s}}\), no particles get picked up by the atmosphere