style="text-align: justify;">Meteorologists have confirmed this observation by recordings made ground on wind, rainfall and cloud height. They also compared with measures of urban pollution made by the EPA (Environmental Protection Agency, Agency for Environmental Protection). The result is statistically significant: with increasing amount of dust in the air, rainfall during summer storms increases. "It is worrying that we are spending the time, Thomas Bell regrets. It seems that we make storms more violent. "We understand this weekly concerns only the storms. The sunny weekends are not due, apparently, to urban pollution ...

This coupling is currently a statistical observation. But a phenomenon is explained very well. We know that in a cloud of dust aggregate the water or ice, forming a supplement drops, which also become larger. The relationship between urban pollution and rainfall had already been demonstrated by the observations of one satellite TRMM. This explanation makes some people say that the same amount of water, the clouds, is sent to the ground. Pollution merely distribute differently over time.

Moreover, other phenomena stimulate the precipitation and the effect of sowing of dust could be secondary. According to the team, the influence of pollution become more important during summer storms, due to winds which are ascending up high altitude solids suspended in the air. Whatever the mechanism, Thomas Bell said that this coupling should be better taken into account for weather forecasts, which tend to overestimate the rainfall of the weekend.