1. The Atmosphere

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

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

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

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

6. Deaths from melanoma in USA30 40 50
Latitude / ºN

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 ?