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Can air pollution can affect weather? I heard that the hurricane Mitch was caused from pollution.
Question Date: 1999-01-25
Answer 1:

Not all scientists agree if weather like hurricane Mitch was caused by pollution. No one is sure. Those that do say that pollution does affect the weather say that pollution causes the air to warm which causes changes in the weather. Scientists do generally agree that on local scales, say around a city, pollution does affect when it rains and makes it more likely to rain on the weekends.

One of the scientists involved is Randall Cerveny at Arizona State University who did the study. Just in case your internet connection is down, here's the text:

"Study suggests weekly hurricane and rainfall patterns are linked to East Coast pollution

Who hasn't felt like going back to work on Monday has affected the weather? It turns out the weather itself may indeed be controlled by the weekly calendar, and that even mighty Atlantic hurricanes may feel the punch of the workweek, according to a study by two Arizona State University researchers appearing in the journal Nature.

Examining some basic data sets in a way that has never been tried before, ASU climatologists Randall Cerveny and Robert Balling, Jr. have found proof for what many a weekend boater has secretly suspected: rain is most likely to occur along the Atlantic coast on the weekend and the weather is most likely to be better on a Monday, Tuesday or Wednesday. The most obvious culprit is the "natural" cloud-seeding effect created by the massive drift of East Coast pollution, which also follows a well defined weekly cycle.

The gray, smelly cloud of pollution has a strange silver lining, however. While pollution makes for more rainy weekends, it also apparently reduces the intensity of hurricanes that hit over the weekend, such that weekend hurricanes tend to be much weaker than, say, Tuesday storms.

"Hurricanes are the biggest storms that we have on this planet, in terms of energy and precipitation," noted Cerveny. "And what we've found is that we're having an impact on them. It's a little daunting, when you start to think about it."

Cerveny and Balling examined and compared three different data sets daily carbon monoxide and ozone measurements from a Canadian monitoring station on Sable Island off the coast of Nova Scotia, daily satellite-derived rainfall data for the Atlantic Ocean, and databases of coastal Atlantic hurricane measurements. In each case, when the two ASU scientists examined the data by day of the week, they found significant differences between days, and similar patterns of variation, with pronounced differences between beginnings and the ends of weeks. All three sets of climate data revealed a seven-day cycle.

"The human week is not a natural time period," said Balling. "Human effect on weather is the only explanation."

"If you're going to go out boating in the Atlantic, you're going to get wet if it's a weekend," Cerveny said. "And what we suggest is that this is probably linked to the pollution cycle."

In examining precipitation in the Atlantic, they found no daily variation when looking at the ocean as a whole, but a pronounced sine-wave pattern of variation for just the coastal areas, with average daily precipitation rising on Thursday and into the weekend and then dipping from Sunday through the middle of the week. Balling notes that when the team analyzed satellite data grid cells for an area a little further away from the coast, they found the same pattern, time-shifted in accordance with the rate of pollution drift.

Though the study does not directly address causation, a comparable fluctuation in the levels of East Coast air pollution points to an obvious connection. The fact that coastal hurricane intensity data taken from 1945 to 1996 follow a similar pattern (rather than being statistically uniform for each day of the week, as one would expect), supports this hypothesis.

"The fact that pollution can affect rainfall is actually well understood," said Balling. "We just had to look for the evidence in the right place. The hurricane data, though, surprised the heck out of me."

"We knew that cities have an effect on local weather with urban heat islands and so forth, and people are pretty sure that we're having a general global effect with carbon dioxide," said Cerveny. "But nobody had ever looked at the in-between area of large-scale regional weather. We appear to be affecting global weather on a scale that is comparable to El Nino."

The hypothesis is particularly important when applied to hurricanes, because of the destructive potential of the storms. Cerveny and Balling looked at 50 years worth of hurricane records, which include observations taken every 6 hours and found surprising statistical differences with important implications.

"Storms are substantially weaker during the first part of the week and stronger in the last part of the week," said Cerveny. "Pollution's thermal changes on the storm are apparently helping hu

Answer 2:

The effect on the weather may not be direct. It could be a result of increased warming, though.What happens when you close all your car windows on a summer day? It gets really hot in there, right? If you leave the windows open, it's a lot cooler. Pollution can form a layer in the atmosphere that doesn't allow heat to escape, just like the windows trap heat in your car. This is called the "greenhouse effect". Many scientists think this will lead to global warming. Others aren't sure. Hurricanes (and all winds) are caused by a mass of warm or hot air meeting a mass of cold air. So with more hot air, can we expect more or worse hurricanes? How could we test that hypothesis?

Here is a site about hurricanes:Envirolink

This site has more information on the greenhouse effect:Greenhouse

Answer 3:

Certain types of pollution can affect weather in the long term. For example, green house gases (some indirectly caused by pollution and others are a direct result of pollution) work by trapping more of the sun's heat energy than normal in our atmosphere, thus warming the planet (global warming). This causes global weather changes. For example, scientists believe that El Nino might be caused by pollution in an indirect way via global warming. Also, the severity and frequency of hurricanes has been steadily increasing in the last several years and scientists believe that also might be due to global warming. However, I am not aware of how pollution can cause immediate effects on weather or very specific effects, such as the generation of a specific hurricane. The greenhouse gases that have been found to be in increased concentrations include carbon dioxide, methane, and even water. Why do you think carbon dioxide levels might be increasing in the past ~100 years?


Answer 4:

I don't know anything about air pollution causing hurricane Mitch, but if is true that pollution can affect weather. The best example of this is that carbon dioxide from power plants and cars has caused Earth's surface temperature to warm about 1 degree Fahrenheit. We know for sure that the earth's surface is getting warmer, and we know for sure that we have polluted the atmosphere with extra amounts of carbon dioxide, but we don't know for sure that the higher carbon dioxide is what is causing the global warming. Computer models, however, make a very good argument for carbon dioxide being the cause.
Air pollution in the form of dust and smoke particles can help clouds to form, and that, too, can have an effect on weather.
I hope this helps.



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