Geoscience Reference
In-Depth Information
Figure 2.
The PM travels hundreds and thousands of miles, as seen in these satellite images for 2004
that illustrate PM density from the Earth's surface to the top of the troposphere (which ranges from
about 4 to 12 miles). Reds generally indicate human-generated sources, greens indicate primarily
natural sources, and browns indicate a blend. Darker colors indicate greater concentrations.
Atmospheric concentrations tend to be strongly to moderately correlated with ground-level
concentrations, depending on local conditions.
Source:
NASA.
