Shop Windows to the Universe

Hands On Mineral Identification helps you to identify over 14,500 minerals! By M. Darby Dyar, Ph.D. See our DVD collection.
Air Pollution can impact visibility in remote areas as well as in cities.
Click on image for full size
Source: T. Eastburn

Air Pollution and Atmospheric Visibility

Have you ever spent time in a large city? If so, the odds are you’ve seen the sky engulfed in a brownish-yellow or grayish-white haze due to air pollution. Such haze can reduce visibility from miles (kilometers) to yards (meters). Mountains or buildings once in plain sight can suddenly be blocked from view.

Air pollution that reduces visibility is often called haze or smog. The term smog originally meant a mixture of smoke and fog in the air, but today it refers to any mixture of air pollutants that can be seen. Smog typically starts in cities or areas with many people, but because it travels with the wind, it can appear in rural areas as well.

One consequence of smog over any given area is that it can change the area’s climate. Smog reduces the amount of the Sun’s energy reaching the Earth’s surface. In some cities, this reduction has been as high as 35 percent on particularly smoggy days. The reduction is greatest when the sun is low on the horizon because the sunlight has to travel through a greater amount of polluted air as its angle drops.

A reduction in solar radiation may not be the only thing air pollution inhibits. It may be altering rainfall patterns as well. Particulates in the air often form condensation nuclei that attract water vapor. When enough moisture accumulates around natural dust particles for example, droplets of rain typically fall. But certain specks of air pollution, such as black carbon, can be too small to produce raindrops big enough to hit the ground. Since rain flushes dust, soot, and chemicals from polluted skies, atmospheric visibility could also be negatively impacted as a consequence.

Scientific field campaigns such as MILAGRO are one way scientists can research atmospheric processes to prove or disprove such ideas. For now, if rain isn't in the forecast when atmospheric visibility is low and smog is high, than wind is likely your best hope for a return to clear skies.

Last modified February 19, 2006 by Teri Eastburn.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Air Pollution

What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have in common? They are all examples of air pollution. Air pollution is not new. As far back as the 13 th century,...more

Introduction to Milagro

One of the most complex field campaigns ever undertaken in the field of atmospheric chemistry began in March 2006. A team of researchers from around the world is in Mexico City for a series of projects...more

Aerosols: Tiny Particulates in the Air

Aerosols, also called particulates, are tiny bits of solid or liquid suspended in the air. Some aerosols are so small that they are made only of a few molecules – so small that they are invisible because...more

Rainbows

Rainbows appear in the sky when there is bright sunlight and rain. Sunlight is known as visible or white light and is actually a mixture of colors. Rainbows result from the refraction and reflection of...more

The Four Seasons

The Earth travels around the sun one full time per year. During this year, the seasons change depending on the amount of sunlight reaching the surface and the Earth's tilt as it revolves around the sun....more

Research Aircraft

Scientists sometimes travel in specially outfitted airplanes in order to gather data about atmospheric conditions. These research aircraft have special inlet ports that bring air from the outside into...more

Anemometer

An anemometer is a weather instrument used to measure the wind (it can also be called a wind gauge). Anemometers can measure wind speed, wind direction, and other information like the largest gust of wind...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA