1. The Atmosphere

2. Physical Stratosphere 15 km 50 km 15ºC -70ºC 15º C Troposphere

3. Chemical – what are the main gases ? Nitrogen Oxygen Argon Carbon Dioxide 78 % 21% 1% 350 ppm

4. What are ppm? ppm = parts per million. so 350 ppm means 350/1000000 = 3.5 × 10 - 4 = 3.5 × 10 - 2 % on your calculator = 0.035 % times 100

5. Now your turn ! What is the % neon in air ? – 18 ppm How many ppm is argon ? 1% 0.0018 % 10000 ppm

6. Deaths from melanoma in USA Latitude / ºN30 4050 o o o o o o o o o o o o o o o o o

7. Why is sunlight more intense at the equator ? smaller distance through atmosphere less spread out

8. What frequencies of radiation are the most dangerous ? Why ?