Chemtrails or Acid Rain ? - The Birth Of Two Myths
The idea that acid rain is some sort of hoax or scam is ludicrous. Sulfuric acid and its environmental effects have been known since ancient historical times. If acid rain is a hoax, then the ancient Sumerians and Greeks were certainly in on it. Modern science has been accumulating facts about environmental damage caused by sulfuric acid since at least 1736, when sulfuric acid was first produced industrially in Britain. When deniers of anthropogenic global warming claim that acid rain is a hoax they demonstrate, not their knowledge of science, but their political preferences, as here for example.
The chemtrail nonsense is an idea put forward by people who would rather believe a conspiracy theory than the physical laws of the universe. Apparently, some mysterious "they" are putting chemicals in aircraft fuel for nefarious purposes. The less extreme theories suggest that "they" are using HAARP to turn the atmosphere into a plasma, and as proof just look at the pretty colors in the clouds. Perhaps these people live in the perpetual haze of cities and have thus never seen rainbows in clouds.
If a plane is 'pumping out chemicals', other than the normal by-products of clean combustion, then maybe one or more engines need attention. What is more likely, however is that "they" are testing new fuels and new engines. If "they" want to dose the world at large with mind-altering substances they can sell it on street-corners for profit, rather than bribe tens of thousands of people to look the other way while the proverbial man in black puts something in a fuel tank.
A brief history of the science and politics of acid rain.
There are some people who want you to think that acid rain is a hoax. In their eagerness to "prove" their "theory" ( aka something they just made up ) they generally start talking about how the hoax began in the 1970s or late 1960s. Certainly the term acid rain came into wide use in the 1970s, but the fact of acid rain was known much earlier. When coal is burned, one of the many byproducts of combustion is sulfur dioxide. This combines with atmospheric moisture to form sulfurous acid. That acid, if it combines with water, turns into sulfuric acid. That's the same acid - but much more dilute - which you get in the lead-acid battery.
As an aside I might mention that one of many methods for determining the environmental effects of airborne acid employed a measuring device which utilized the same reaction that damages lead-acid batteries: sulfation. The degree of sulfation of a lead(IV)oxide surface exposed to air for a month is a measure of the corrosive effects of that air. That proxy method was used in the 1930s to measure the effects of coal smoke in Britain.