Air quality in this area varies significantly by season, with the summer season typically having the poorest visibility and winter season the best. Summer winds are from the southeast while winter winds are from the north and west. Nearly half of Big Bend’s visibility reduction is due to sulfates. During the summer, air masses arriving in this region from the southeast bring the highest concentrations of sulfates and the poorest visibility conditions.

Where is Today's Air Coming From?
view the trajectory maps

Using back-trajectory analysis, researchers can back-track prevailing wind patterns and trace the origin of pollutants. A typical summer wind pattern for Big Bend may begin two days earlier in East Texas, circulate into Louisiana, dip south along the Gulf Coast, migrate west into Mexico, and finally blow toward the northwest into this area. This wind pattern may collect, transport, and deliver such pollutants as sulfates, organic carbons, nitrates, and wind blown soil particles.

Nearly half of Big Bend's visibility reduction is due to sulfates. Data suggest that sulfur emissions from nearby Texas and Mexican coal-fired power plants and industrial processes help create the white haze that often diminishes or obscures the scenic landscapes in Big Bend National Park.