1. 1 Surface Conditions Surface temperature averages -63 o C, but typically varies from -89 o C to -31 o C. –the Viking landers occasionally measured temperatures > 0 o C, and at least once up to 80 o F. Surface Gravity: 3.7 m/s 2 (0.38 G) Albedo: 0.15 Solar Irradiance 589 W/m 2 (43% of earth) 68

2. 2 Mars’ Atmosphere 95.3% CO 2 and 2.7% N 2, with 1.6% Ar and small a amount of O 2 (0.13%). This is almost the same composition as what other planet’s atmosphere? 69

3. 3 70

4. 4 Atmospheric Pressure The pressure of the atmosphere on Mars is only about 7 millibars. The average pressure on Earth is about 1000 millibars. When the air pressure is this low, liquid water simply boils into water vapor. This explains why no liquid water can exist on the surface of Mars today. But who knows about under the surface…. 71

5. 5 Weather Conditions With the low temperatures, low barometric pressure and almost no water vapor, the most common type of “weather” on Mars is dust storms! 72

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7. 7 74

8. 8 www.spacescience.org/ExploringSpace/Gallery/MercerPaintings/MarsDustStorm213.JPG 75

9. 9 Precipitation! – NOT! No precipitation falls on Mars, at least not in the same way it does on Earth - no rain, no snow, no sleet. Sometimes frost does form on the rocks. 76

10. 10 Probably solid CO 2 77

11. 11 78

12. 12 Weather Forecast Despite the very thin atmosphere, Mars has very active weather –Winds of 2 to 30 m/s (67 mph) –Local & planet-wide dust storms –Frost in low-elevation areas –Dust devils (next 2 slides) –Southern polar cap sublimation of CO 2 adds atmosphere in S.H. summer. 79

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15. 15 The Polar Ice Caps The northern ice cap is made up mostly of frozen water ice – just like on earth! The southern cap is water ice underneath, but there’s a thick layer of dry ice (frozen carbon dioxide) over the water ice. 82

16. 16 The ice caps shrink and grow with the seasons. All of this material goes into the atmosphere, doubling the air pressure in summer. btc.montana.edu 83

17. 17 Local winter to summer changes in the south polar “ice” cap (frozen CO 2 ) Part of Mars’ atmosphere is lying frozen on its surface! 84

18. 18 June, 2003Oct, 2003 85

19. 19 86

20. 20 Layers result from sublimation and freezing cycles. North polar cap. 87