How the products of fire control the formation of snow

You might expect more interesting organic chemistry in the smoke above a barbecue than in the pristine snows of the Swiss Alps, but for organic atmospheric chemist Nadine Borduas-Dedekind, they’re intricately connected. The aerosols, dust and large molecules thrown in to the atmosphere by fires are exactly the kind of particles that drive water droplets to become ice crystals in clouds. And so her team has found itself stoking a barbecue on her lab’s roof to sample early precursors to those ice-nucleating particles as well as trekking through the alpine wilderness to recover the real thing at the end of its atmospheric journey.