Earth’s twin planet in the Solar System, Venus, has an ozone layer. The Venus Express space craft detected the signature of ozone about 100 km up in Venus’s atmosphere.
Ozone is a molecule of oxygen containing three atoms of oxygen (O3) rather than the normal two (O2) that we breathe. It forms when ultra-violet light acts on oxygen molecules in the atmosphere. It then blocks some of the ultra-violet light from reaching the surface of the Earth. This makes our planet liveable – too much UV light is very harmful to organisms, which is why you have to wear sunscreen when you go outside on a sunny day.
Some chemicals in the atmosphere can damage the ozone layer. This was once not well understood but now damage to the ozone layer is monitored carefully. The international ban on the use of chemicals called CFCs (which used to be the propellant in aerosol cans) is a great example of the world uniting to stop human activity from damaging the environment. The ozone layer changes over time and the large hole over the Antarctic has just passed through its seasonal maximum in September. It continues to be a concern but it does seem to have stabilised.
Please do not trot out “the ozone layer” as a problem caused by burning fossil fuels. It is vitally important that you can distinguish greenhouse gases that are causing global warming from other environmental problems. One year, so many boys answered the question, “What environmental problem is caused by the excessive release of carbon dioxide into the atmosphere?” with, “It is damaging the ozone layer,” that I stuck little notices all around the school saying, “It is NEVER the ozone layer!” Of course, sometimes the answer will be ozone related but please read the question carefully!
Questions…
- Which is the only planet nearer to the Sun than Venus?
- What percentage of dry air on Earth is oxygen?
- CFCs are produced from simple hydrocarbons. Name a simple hydrocarbon.
- What two molecules are produced when hydrocarbons burn completely in air?
- What substance might form if a hydrocarbon burns in a limited supply of oxygen?
1. Mercury.
2. 21%.
3. Methane.
4. Carbon dioxide and water.
5.carbon monoxide and water.
Q1 – excellent
Q2 – splendid
Q3 – indeed
Q4 – hurrah!
Q5 – well done
Terrific stuff all around!