August 3, 2012 | Corrinne

I was really shocked by the news of the terrible rainstorm that hit Beijing last month, when 77 people died. How could this happen in a modern city?

Scientists think Beijing’s sheer size made the storm worse. Massive cities create ‘urban heat islands’, because when you replace grassland with concrete, the air gets warmer. And tower blocks pump even more heat into the atmosphere. This warm air can trigger severe downpours.

Future cities should be built using white or reflective material, say scientists. That would help the air keep its cool.