Difference Between Acid Rain and Normal Rain

The key difference between acid rain and normal rain is that the acid rain contains a large amount of sulfur dioxide and nitrogen oxide gases dissolved in it than the normal rain.

The water, which is in oceans, lakes, and other reservoirs on the earth surface, evaporates in the daytime. Trees and other organisms also give out a considerable amount of water. The evaporated water is in the atmosphere, and they aggregate and form clouds. Due to the air currents, the clouds can travel to farther locations than where they form. The water vapour in the clouds can come back to the earth surface in the form of rain. And, this is what we call the water cycle.

CONTENTS

1. Overview and Key Difference
2. What is Acid Rain
3. What is Normal Rain
4. Side by Side Comparison – Acid Rain vs Normal Rain in Tabular Form
5. Summary

What is Acid Rain?

Water is a universal solvent. When raining, the rainwater tends to dissolve substances, which are dispersed in the atmosphere. Today the earth’s atmosphere has been highly polluted due to human activities. When there are sulfur dioxide and nitrogen oxide gases in the atmosphere, they can easily dissolve in rainwater and come down as sulfuric acid and nitric acid. Then the pH of the rainwater becomes less than 7, and we say that it is acidic.

Figure 01: Harmful Effects of Acid Rain

Over the past few decades, the acidity of rain has increased significantly due to human activities. For example, SO2 forms during fossil-fuel burning, and in industrial processes, H2S and S forms. Nitrogen oxide also forms from fossil fuel burning and power plants.

Other than human activities, there are natural processes where these gases forms. For instance, SO2 forms from volcanoes, and NO2 forms from soil bacteria, natural fires, etc. Acid rain is harmful to soil organisms, plants, and aquatic organisms. Moreover, it stimulates corrosion of metal infrastructure and other stone statues.

What is Normal Rain?

Rain is the main form in which the evaporated water from the earth surface is coming back to the earth. We call it liquid precipitation. The atmosphere contains water vapour, and when they get saturated in a certain place, they form a cloud. The saturation of air is easier when it cools than when it is hot. For example, water vapour cools when it comes into contact with a colder surface.

Figure 02: Rain falling on the Ground

To rain, the water vapour, which is in the form of tiny droplets, should combine and form larger water droplets. We call this process as coalescence. Coalescence takes place as the water droplets collide with each other, and when the drop is heavy enough, it falls. The rainfall patterns vary according to the geographical differences. There, the deserts get minimum rainfall over the year, whereas rainforests get a very high rainfall. Also, various other factors such as wind, solar radiation, human activities, etc. affect rainfall patterns. Rain is very important for agriculture. Earlier, people were completely depended on the rainwater for their agriculture. Today also most of the agriculture depends on the rainwater.

What is the Difference Between Acid Rain and Normal Rain?

Rain is the way that water in the atmosphere comes to the ground. Rain is very important for our day to day life. Acid rain is a harmful form of rain. The key difference between acid rain and normal rain is that acid rain contains a large amount of sulfur dioxide and nitrogen oxide gases dissolved in it than the normal rain.

Usually, the atmosphere contains acidic gases from natural processes. Therefore, they are dissolved in rainwater, and consequently, the pH of it is slightly acidic and just below pH 7. But, the acid rain pH is far less than this value, which can come down to pH 2-3 at times. Therefore, the level of acidity contributes to another difference between acid rain and normal rain. Moreover, acid rain is harmful to the organisms, and the infrastructure whereas normal rain is not.

Summary – Acid Rain vs Normal Rain

Rain is an important incident that takes place in the environment, and we get many uses out of it. However, if the rain has harmful components dissolved in it, we cannot use for desired purposes. Acid rain is one such form of rain. The key difference between acid rain and normal rain is that the acid rain contains a large amount of sulfur dioxide and nitrogen oxide gases dissolved in it than the normal rain.

Reference:

1. Bradford, Alina. “Acid Rain: Causes, Effects and Solutions.” LiveScience, Purch, 14 July 2018. Available here 

Image Courtesy:

1.”Acid rain woods1″By Lovecz – Own work, (Public Domain) via Commons Wikimedia  
2.”Vihm Osula küla talivilja põllul”By Aleksander Kaasik – Own work, (CC BY-SA 4.0) via Commons Wikimedia  

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