there is a discrete but incomplete layer of ozone in the atmosphere

Some learners may think that

  • there is a layer of ozone high up in the atmosphere
  • there is/are one or more holes in the layer

"So why don't today's refrigerators use Einstein-Szilard compressors? The answer is that while AEG in Berlin was developing the device, General Motors invented a new coolant called Freon at their research laboratory in Drayton, Ohio. As Freon was considerably less toxic than previous coolants, switching to it was a much cheaper way for manufacturers to improve refrigerator safety than by mass-producing a new pump. Little did manufacturers know that Freon, part of a class of chemicals known as hydrofluorocarbons, would cause a hole in the ozone layer in the Earth's upper atmosphere."

Paul Sen (2022) Einstein's Fridge. The science of fire, ice and the universe. William Collins.

[Note: Freon is used as a trade name for a number of different compounds, including chlorofluorocarbons and hydrofluorocarbons, used as coolants.]

The atmosphere is (largely) gases, which will freely mix. The recognised 'layers' in the atmosphere relate primarily to different physical properties (such as temperature), but there are no absolute divisions as gases (and water droplets, dust, etc.) move between 'layers'.

The 'ozone layer' is not a layer of ozone, but refers to the part of the atmosphere where the presence of ozone (as one small component of the mixture of gases) is active in absorbing radiation which could be harmful if it reached ground level.

Depletion of the ozone in the 'ozone layer' (due to reaction with synthetic compounds* such as the chlorofluorocarbons, CFCs, that were historically produced for applications such as refrigeration because of their great stability and low toxicity – and which had escaped into the atmosphere at ground level and diffused to higher altitudes) did not occur uniformly, but predominantly in polar regions due to the presence of clouds that facilitate the reactions, so that ozone concentrations in these regions were much lower (up to about 60% depletion at its most extreme) than in other parts of the 'layer'. The so-called 'holes' were thus regions of substantially lower concentration, but were not areas with no ozone at all.

So, there is an 'ozone layer' but it is not a layer of ozone, and 'holes in the ozone layer' form, but they are not actually holes.

* Some ozone depletion also occurs naturally, so ozone concentrations may fall after major volcanic eruptions.

Read about the nature of alternative conceptions

Read about some examples of science misconceptions

Read about historical scientific conceptions

Author: Keith

Former school and college science teacher, teacher educator, research supervisor, and research methods lecturer. Emeritus Professor of Science Education at the University of Cambridge.