1. What causes anticyclones to form? 1. Rossby waves (as they turn away from poles). 2. Dense, cool air in winter over large continental areas. 3. Semi permanent areas of high pressure associated with the global atmospheric circulation e.g. subtropical high pressure zone.

7. Short term climate change Short term climate change operates over periods of up to a 1000 years. El Ni ño is an example of very short- term widespread climatic disruption.

11. How does the ENSO work? A normal year.

12. How does the ENSO work? An El Ni ño year .

13. How does the ENSO work? A La Ni ña year .

14. Global Warming: TRUE or FALSE

15. 1. Gases in the Earth’s atmosphere keep the Earth warm by absorbing longwave radiation leaving the Earth’s surface. This naturally occurring effect is called the greenhouse effect. 2. Without the Greenhouse effect the Earth would be about 10 °C colder . 3. The main greenhouse gases are: carbon dioxide, methane, helium and nitrogen oxide. TRUE FALSE FALSE

16. 4. The concentration of greenhouse gases has decreased over the last 100 years. 5. The Earth’s average temperature has increased by about 0.5 °C over the last 100 years due to an enhanced greenhouse effect . 6. The main causes of global warming are an increase in transportation by vehicles, greater use of electricity by homes and industry and clearing forests for farming. FALSE TRUE TRUE

17. 7. The Earth’s climate does not change naturally. 8. Global warming will increase the number of extreme weather events like floods and hurricanes. 9. Global warming will cause sea-level to fall because warmer temperatures mean more evaporation of water from the sea. 10. Global warming will cause ecosystems and habitats to move towards the poles. FALSE TRUE FALSE TRUE

20. The natural greenhouse effect

21. The enhanced greenhouse effect