Chemistry and Clouds

Researchers look at water droplets and chemical reactions.

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Herckes’ team found that clouds provide the water medium and the surface for nitrosamines’ formation. “It is possible that the reaction happens at the surface of the droplet,” he says.

Interestingly, they form in fog and cloud droplets almost always at night. Later, as the fog evaporates, they become gaseous. The sun then quickly destroys them. “They are in the air in high amounts, but for a very short time, and we are far from understanding (human) exposure,” he says. ‘” We don’t know whether breathing these can cause cancer.”

Unlike other researchers who study cloud and fog chemistry in the laboratory, Herckes and his team actually go into the field to collect cloud and fog samples. They have visited mountains in Northern Arizona and on Mt. Whistler in Vancouver, site of the 2010 winter Olympics, and the fog prone areas of Central California.

They drive and hike to the top--easier and less expensive than flying--then collect their samples by drawing the air with fans past a series of strings, causing the droplets to hit the strings and the water to run into sampling bottles.
Probably the most difficult part of the field experience is having enough patience to wait for the clouds and fog to arrive.

“Waiting for a cloud to hit a mountain, or a fog to form, can be a frustrating experience,” he says. “The right meteorological conditions can be difficult to anticipate, and weeks can go by without an event. More than once, we wondered if our sole presence to sample clouds and fog makes them disappear.  Maybe, if our research is ever stalled, we can sell our services as fog/cloud prevention.”