In wet weather pollen grains can fragment into tiny particles that can ‘constipate’ clouds
Not only do pollen grains make us sneeze, they may also be reducing rainfall. In contrast to earlier findings, a new study shows that pollen grains suppress rainfall by an average of one-third in non-polluted continental areas, and in some areas they ensure that not a drop falls.
During pollen season every cubic metre of air contains somewhere between 10 and 1,000 grains of pollen. But when the weather is wet or humid these pollen grains can swell and burst, fragmenting into up to 100m tiny particles per cubic metre.