The Atmospheric System 6.1

Transcription

1 The Atmospheric System 6.1

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3 What is the atmosphere? Layer of gas that surrounds our planet.

4 The atmosphere is a dynamic system with inputs, outputs, storages and flows. Heat and pollutants are carried across the Earth by air currents in the atmosphere. Over geological time the composition of the atmosphere has changed greatly. The concentrations of atmosphere gases such as ozone, carbon dioxide, methane, and water vapor have significant effects on ecosystems.

5 What percent would you place on the following gasses in Earth s Atmosphere? Carbon dioxide Oxygen Nitrogen

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9 Although the atmosphere is approx.. 1,100 km in depth, the stratosphere (10-50km) and the troposphere (less than 10km) are where most reactions affecting life occur. Examples: The ozone layer and cloud formation Human activities and activities by other organisms impact the atmosphere composition through altering inputs and outputs of the system. The atmospheric composition affects activities of human and other organisms.

10 Past atmospheric changes The atmosphere and climate of Earth have always changed. Climate is unstable and has fluctuated greatly in the past. What are some abiotic factors that could influence climate? Temperature Precipitation What are some biotic factors that could influence climate? Plants animals

11 We can t measure precipitation in the distant past but we can measure temperature and atmospheric gas composition. This is done by bubbles trapped in ice core samples In addition using sediments and fossilized animal shells

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16 Earth s first atmosphere had no free oxygen in the atmosphere. There were no plants to produce photosynthesis. Photosynthetic prokaryotes were producing oxygen, however it was being used up in weathering of minerals. Most notably iron.

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19 The first land plants were mosses and these evolved into larger plants. Just like primary succession

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21 What do you think the carboniferous period looked like? Hint: Period where almost all our ancient sunlight was created

22 Carboniferous Period

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24 Carboniferous period 300 MYA Beginning of Carboniferous period Earth s average temp was 20 C (68 F) Later in the period Earth cooled to an average of 12 C (53.6 F) This is close to our current average temp. of 15 C (59 F) CO 2 levels 1500 ppm 350 ppm 450 ppm

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26 1. What is the relationship between carbon dioxide and temp. in graphs? 2. What other factors besides atmospheric carbon may influence Earth temps? (Think greenhouse gases) 3. How do we get the data? 4. Can we rely on the data collection method used?

27 The Greenhouse Effect The greenhouse effect is a natural and necessary phenomenon maintaining suitable temperatures for living systems Without it there would be no life on Earth

28 Venus has a runaway greenhouse effect the planet is covered in a thick atmosphere of greenhouse gasses. 863 F

29 Mars has a very thin atmosphere and can t hold heat. -85 F F

30 45% is absorbed scattered or reflected by the atmosphere (IB text says 50%) 55% reaches the surface: 4% reflected 51% absorbed

31 The 51% absorbed energy creates the following processes: Photosynthesis Heating of the ground and sea Evaporation This energy is released back to the environment and atmosphere as longer wavelength infrared energy (heat)

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35 C0 2 carbon dioxide CH 4 methane N 2 0 nitrous oxide H 2 0 water vapor If we had no GH gases then at night Earth would cool drastically. Life would not survive.

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37 Use page 277 to diagram the solar radiation reaching Earth.