By Sid Perkins
The picturesque hazes of Tennessee’s Smoky Mountains appear when volatile organic chemicals released by trees react with other gases in the atmosphere. And every time a raindrop falls into the ocean, microscopic droplets of salt water splatter upward into the atmosphere. Both mountain haze and fine ocean spray are nature’s aerosols. People’s penchant for burning fossil fuels is now creating a rival source of aerosol formation.
Liquid droplets and solid particles small enough to remain suspended in air can scatter light in ways that make for hazy mountain vistas, stunning sunrises and sunsets, and urban smog. Scientists, however, are finding that these aerosols also play critical global-scale roles in climate and atmospheric chemistry. The researchers have been examining lab-made and natural aerosols in an effort to discover how their constituent particles form, what effects they have on the atmosphere, and whether something needs to be done about them.