The easiest way to distinguish between stratospheric ozone and tropospheric ozone is by looking at the difference in the ozone concentrations in each atmospheric layer. Stratospheric ozone concentration is very high, whereas tropospheric ozone concentration is low.
Stratospheric ozone and tropospheric ozone are the two types of ozone gas in the ozone layer. These two types are named as such, not due to any chemical difference but due to the distribution of the ozone gas.
CONTENTS
1. Overview and Key Difference
2. What is Ozone Layer
3. What is Stratospheric Ozone
4. What is Tropospheric Ozone
5. Stratospheric Ozone vs Tropospheric Ozone in Tabular Form
6. Summary – Stratospheric Ozone vs Tropospheric Ozone
What is Ozone Layer?
Ozone layer is a shield or region of Earth’s stratosphere that can absorb the Sun’s UV radiation. This region contains a high concentration of ozone compared to ozone content in other parts of the atmosphere. Typically, the ozone layer consists of an average of 0.3 ppm ozone gas.
Figure 01: NASA’s projection from 1974 to 2060 of the impact of CFCs on the Ozone layer if they hadn’t been banned
We can find this region mainly in the lower part of the stratosphere, but its thickness can vary from season to season and also geographically. More importantly, the ozone layer can absorb 97 to 99% of the UV radiation that comes from the Sun. Otherwise, this UV radiation can damage our skin and eyes if we are exposed to ozone.
What is Stratospheric Ozone?
Stratospheric ozone is the ozone gas that occurs in the stratospheric layer in high amounts. About 90% of the total ozone concentration in the atmosphere of Earth occurs in the stratospheric layer. The average amount of ozone in this layer is about 0.3 ppm by volume of the atmosphere. This type of ozone occurs at heights between 15 to 35 kilometres above the Earth’s surface. The ozone gas in this layer can absorb about 97-99% of the UV radiation that reaches the Earth. However, the amount of ozone gas in this layer is damaged by chlorofluorocarbons, and it led to ban these chemicals from use.
Usually, the ozone gas in this layer is formed from the chemical reaction that takes place when UV radiation coming from the Sun strikes an oxygen molecule. This reaction can cause the splitting of oxygen gas, forming atomic oxygen. This atomic oxygen can react with molecular oxygen to form ozone.
What is Tropospheric Ozone?
Figure 02: Tropospheric Ozone
Tropospheric ozone is an ozone gas that occurs in the troposphere in trace amounts. The average concentration of ozone in the troposphere is 20-30 ppb when considering the volume. However, the polluted area of the atmosphere contains about 100 ppb. The ozone layer exists between 10 to 50 kilometres above Earth, in the atmosphere where the stratosphere occurs. The lowest layer of atmosphere on Earth’s surface is the troposphere. The average height of this layer is about 14 kilometres from Earth’s surface (concerning the sea level). Therefore, we can find the least amount of ozone in this area.
When considering the creation of the tropospheric ozone, it is formed from the chemical reaction between oxides of nitrogen and volatile organic compounds at the ground layer of the atmosphere. This reaction takes place in the presence of sunlight to form ozone gas. The concentration of ozone gas increases as the height above sea level increases. The maximum concentration occurs at the tropopause. It is the boundary between the stratosphere and troposphere. Although the ozone layer is very important to us, the ozone gas in the troposphere is considered a greenhouse gas that can contribute to global warming.
How to Distinguish Between Stratospheric Ozone and Tropospheric Ozone?
The easiest way to distinguish between stratospheric ozone and tropospheric ozone is by looking at the difference in the ozone concentrations in each atmospheric layer. The key difference between stratospheric ozone and tropospheric ozone is that stratospheric ozone concentration is very high, whereas tropospheric ozone concentration is low. Moreover, we can distinguish stratospheric ozone from tropospheric ozone by observing the formation of the ozone gas. Ozone gas in the stratosphere is formed from the reaction between atomic oxygen with molecular oxygen. In contrast, ozone gas in the troposphere forms from the reaction between oxides of nitrogen and volatile organic compounds in the presence of sunlight.
The following table will help you to distinguish between stratospheric ozone and tropospheric ozone.
Summary – Stratospheric Ozone vs Tropospheric Ozone
The easiest way to distinguish between stratospheric ozone and tropospheric ozone is by looking at the difference in the ozone concentrations in each atmospheric layer. Stratospheric ozone concentration is very high, whereas tropospheric ozone concentration is low.
Reference:
1. “Why Is Ozone Layer Formed in Stratosphere? “Askinglot.
Image Courtesy:
1. “Future ozone layer concentrations” By NASA/Goddard Space Flight Center Scientific Visualization Studio – NASA, Public Domain) via Commons Wikimedia
2. “Tropospheric Ozone (O3)” By GRID-Arendal (CC BY-NC-SA 2.0) via Flickr