1 Ozone module prepared by Eugene C. Cordero Lesson 1: Ozone and UV radiation

2 Ozone module prepared by Eugene C. Cordero Learning Objectives  To understand the role ozone plays in the Earth’s system.  To understand how surface Ultraviolet (UV) radiation varies.

3 Ozone module prepared by Eugene C. Cordero What is ozone?  The ozone molecule contains three oxygen atoms, hence O 3 is ozone.  How is ozone produced? –It is formed when oxygen absorbs solar radiation O 2 +h ( <240nm)  O+O O+ O 2  O 3 –Ozone reacts with various other chemicals, and thus is highly reactive. –Ozone also absorbs incoming UV radiation O 3 + h ( <320nm)  O 2 +O

4 Ozone module prepared by Eugene C. Cordero Ozone formation

6 Ozone module prepared by Eugene C. Cordero Good ozone/bad ozone

7 Ozone module prepared by Eugene C. Cordero Why is the ozone layer important  Ozone acts as the Earth’s protective shield against the Sun’s harmful Ultraviolet radiation (UV radiation).  Without the ozone layer, life would not exist on Earth!  The natural development of the ozone layer permitted life to evolve above water.

8 Ozone module prepared by Eugene C. Cordero Ozone in the Atmosphere  Ozone is mainly produced in the tropics because of the higher amounts of solar radiation.  Ozone is mainly destroyed at middle and higher latitudes by chemical processes.  Ozone is also largely affected by atmospheric winds. Thus, ozone naturally has large variations in space and time.

9 Ozone module prepared by Eugene C. Cordero Satellite Ozone Observations

10 Ozone module prepared by Eugene C. Cordero The ozone layer for one day

11 Ozone module prepared by Eugene C. Cordero Dobson Units (DU) as a measure of total ozone definition of ozone hole: < 220 DU Melbourne Avg DU Darwin Avg. 260DU

12 Ozone module prepared by Eugene C. Cordero UV radiation  UV radiation is emitted from the sun with wavelength from nm (nanometers)  UV radiation is divided into three ranges –UV-A, nm –UV-B, nm –UV-C, nm  The shorter wavelength are more harmful to biological life.

13 Ozone module prepared by Eugene C. Cordero Ozone profile with height and UV

14 Ozone module prepared by Eugene C. Cordero Typical UV forecast

15 Ozone module prepared by Eugene C. Cordero UV radiation What affects the amount of UV radiation hitting the Earth?  -Location (latitude)  -Time of day  -Time of the year  -cloud cover Thus, UV radiation naturally has large variations in space and time!!!

16 Ozone module prepared by Eugene C. Cordero UV changes during the day

17 Ozone module prepared by Eugene C. Cordero Satellite UV measurements July 1, 2000January 14, 2000

18 Ozone module prepared by Eugene C. Cordero Summary  Ozone is produced and destroyed naturally in the atmosphere (ozone bucket picture).  Ozone is responsible for absorbing much of the sun’s harmful UV radiation.  UV radiation varies due to time of day, season, cloud amount, and ozone amount.