Though humanity hasn’t discovered how to control the weather, we certainly can influence it. Land use changes and air pollutants have both been shown to influence weather and climate. In cities, the urban heat island effect can alter both where and how much precipitation falls. Likewise, aerosols emitted from power plants, oil refineries, and other sources cause atmospheric changes that result in more intense storms. 

Many studies focus on the effects of urban land cover and air pollution individually, but fewer focus on how these two processes work together. To what extent do they affect weather events like rain? This question is especially important Houston, Texas, which is not only one of the largest cities in the US by area, but also produces high amounts of aerosol particles due to its many oil refineries. 

A new study published in Atmospheric Chemistry and Physics sought to understand how Houston’s landscape and aerosol emissions impact its rainstorms. To do this, researchers ran four simulations of a storm that occurred in the region in June 2013. Each simulation toggled aerosol pollution on or off, or replaced the Houston urban area with croplands and pastures similar to those that are present outside the city. 

Using these models, researchers determined that Houston’s aerosol pollution caused storms to produce 30 percent more peak rainfall and made intense rain eventsq five times more likely. Furthermore, when this aerosol pollution occurred within the city of Houston, the two processes amplified each other, creating even more rainfall and further increasing the probability of experiencing higher intensity storms. 

While this study looked at Houston specifically, its results have much broader impacts. Studies like this give us a better idea on how storms will be impacted as cities continue to expand to accommodate our growing urban population. In addition, this research helps weather forecasters more accurately predict when hazardous weather will occur. This can, in turn, save lives and limit the destruction these natural events often cause.