The word smog originally came from the combination of fog and smoke. The U.S. Environmental Protection Agency has a great article on the history of smog.

Today, the scientific term we use is photochemical smog. Simply put, this is what forms when pollutants react with the sun to form ozone, the same chemical that protects us from the sun, but is hazardous in the lower level of the atmosphere. Los Angeles is an example of a city in the United States with a lot of smog.

Here are a few links to pictures of smog:

Here are a couple of pictures of smog in London.

In this picture you can barely see Los Angeles.

I am surprised the cars do not have their lights on in this picture taken in China.

Here is a picture of the sun as seen through smog in Beijing.

If you are interested in air pollutant levels in your town or across the country, you can find that data here, from the federal government.

Another site from the American Lung Association ranks the cleanest and most polluted cities based on ozone, short-term particles and year-round particles. I looked on the site to find the city most polluted by ozone, short-term particles and year-round particles. The following cities were number one respectively: Los Angeles, Calif., Bakersfield, Calif. and Pittsburgh, Pa.

Similarly, the cleanest cities by ozone, short-term particles and year-round particles respectively were Billings, Mont., Alexandria, La., and Cheyenne, Wyo.

Consumer1 said, “I spoke recently with a person who mentioned some folks from China visiting the United States. He said because of the smog in the large city they are from, they have never actually seen a lightning bolt. He said the brown sky just lights up when there is lightning. Do you think there is any truth to this?”

The picture above, from Beijing, shows the sun on a “clear day” through smog; you cannot see the outline of the sun. In the other photos, it is hard to make out buildings and cars in the cities. If you think about a foggy morning, you can’t see the moon or stars through the dense fog. I think if the smog really was that bad, you would see the “smog” light up, but it would be very difficult to see the actual lightning bolt, especially the way we see lightning in Northeast Kansas.