Raindrops are travelling farther than they used to, according to new research that shows warmer air is altering not only the amount of rain but also where it falls. The study, led by Travis Aerenson of the University of Wyoming, modelled atmospheric moisture movements in the US over more than three decades.
Moisture travelling farther and staying aloft longer
The researchers found that in the southwestern and southern plains, moisture in the atmosphere now travels 30 to 50 miles (50 to 80km) farther than it did 35 years ago. It also stays aloft for an extra two to four hours before falling as rain.
Warmer air can hold more water vapour, which means the vapour stays aloft longer and travels farther before condensing and falling. The findings, published in Geophysical Research Letters, also show that more evaporation is occurring from ocean surfaces and less from land surfaces.
Implications for water security and collaboration
The change in atmospheric moisture pathways affects where and when precipitation occurs, with implications for land use. The researchers note that the trend for moisture to travel farther will result in the water security of more countries and states falling increasingly outside their borders, requiring greater collaboration between neighbours.
