David Eldred
From GeoClasses
Smog and Geography: Santiago de Chile
Introduction
Through my travels around the world, I have experienced many climate types. From blistery-cold Maine winters to scorching 110° summers in the desert of the Cuyo region of Argentina. However, one of the most unusual phenomenons that I have encountered is the unique climate of Santiago, Chile. I lived in Santiago de Chile for about a year and a half and during my time there I came face to face with some of the most awesome examples of air pollution that I have witnessed. If you travel internationally much, especially to densely populated, urban areas, then you have probably experienced some of what I am going to talk about. However, Santiago is very different. General speaking, Santiago has a Mediterranean climate with cool coastal breezes that come in off of the Pacific ocean. It is a dry climate with most of the rain, albeit not very much by our standards, comes in the winter. It never gets cold enough to snow and the dust is quite obnoxious. It has one unique feature, its geographic location. It is tightly fit between a smaller coastal mountain range and the towering Andes mountains. This acts as an inescapable trap for all the air pollution that is generated by the huge metropolis. The city boasts 6 million people and is the industrial center for the entire country. As such a producer of ambient contamination matched with its unfortunate geographical location makes for an especially exaggerated example of the harmful effects of pollution.
Geographic and Anthropogenic Causes
As I mentioned in the introduction, Santiago is not unlike many other large urban areas with serious pollution problems. In fact, many other cities in the world produce as much and sometimes many times more the pollution as Santiago. Most of those cities are in geographic locations that provide them with a constant flow of air from winds that help carry the air pollution away from the city. Santiago has no such luck. It is located, basically, in a hole. Stuck between two mountain ranges, the coastal range (6,561ft.) and the Andes (19,500ft.) that surround the city prevent the pollution that is released from escaping or from being carried away by the coastal winds. The principal reason that the air cannot circulate is that the Andes mountains literally tower over the city. The peaks are so tall and the city is so close to the tall peaks that the air has no place to go. The pollution is formed in the Santiago valley and remains there.
There are times when the pollution is not as strong. In fact, there is a difference in the intensity of the smog between summer and winter. This is due to a temperature inversion that occurs with the changes of the seasons. A temperature inversion is a meteorological phenomenon in which air temperature increases with height for some distance above the ground, as opposed to the normal decrease in temperature with height. In the summer, the temperature inversion is much higher in the atmosphere. This gives the smog more area to expand and not be as concentrated as much toward the ground. In the winter, the effect is reversed. The concentration of smog is found very close to the surface and can be very restrictive. Interestingly enough, many times there can be breaks from the asphyxiating effects of the smog. The winds have a great deal to do with how the smog will affect the city. In the winter, high-pressure cold fronts are more common and with them bring more and stronger winds. These strong winds help to carry away the smog away from the city that normally would linger around for many days at a time. Often times the prettiest and most smog-free day is the day immediately after a big winter storm, sometimes lasting one or two days. Many of my pictures were taken during times like this. In the summer, the smog is bad, but not as bad as in winter. However, the drastic changes brought about by the large winter storms are absent. Occasionally, a strong wind comes from the ocean and eases the smog a little. Many people mistakenly, think that the smog is dampened by the rain that accompanies the large winter storms. This is not likely so. Often times, large fronts move through the metropolitan area that do not bring with them rain, but do bring strong winds. You can still see the effect of the winds even without the rain during situations like these.
