The accurate term for this phenomenon is acid precipitation,as it does not only occur with rain. When saying acid rain, we generally refer to the deposition of acidic components in rain, snow, fog, dew, even to dry particles.
The rain is always a bit acid, due to the excistence of carbon dioxide in the earth's atmosphere. When it exists in small quantities, it reacts with water to produce carbonic acid, which is weak and harmless. So, clean or unpolluted rain has a slightly acidic pH of 5.6 (having grade 7 as neutral) However, this is not the case when we talk about acid rain.
Human activities have increased carbon dioxide and other greenhouse gases (term for gases that cause the greenhouse effect) primarily sulfur oxides and nitrogen oxides. Those,with water in the air,react to form strong acids (sulfuric and nitric acids) which are not at all harmless. On the contrary they are the ones to be blamed for every catastrophe acid rain cause.
But how can we stop this phenomenon? The human activities mentioned before do not only include the large industries and factories, but each and every citizen. Wanting to stop acid rain and all its concequences,people have to reduce their carbon dioxide and other emissions. From the most important ones, like stop using cars, to the slightly blamed, like stop covering walls with graffities, we know what to do and we have to do it now.
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