Earth's Atmosphere & Hydrosphere

Grace Boyd, Kaley Barfield, and Kaylee Villareal

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1. How does the Earth’s atmosphere protect and nurture life?

The atmosphere protects the Earth by absorbing the relatively dangerous parts of the EM (Electromagnetic) spectrum known as UV (Ultra Violet) radiation. It also keeps the Earth warm by retaining thermal energy.

2. The hydrosphere includes what areas on earth?

The hydrosphere is the combination of all water on, above, and below earth (the water cycle)

3. How do the geosphere and the lithosphere differ?

4. What are the main gases in Earth’s atmosphere, and their respective proportions today?

Nitrogen (78%) and Oxygen (21%) are the main gasses.

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5. Describe the hypothesized first atmospheric gases on Earth.

Hydrogen and Helium

They were probably lost to space early in Earth’s history because:

  • Earth’s gravity could not hold in the lighter gasses

  • Earth still did not have a differentiated core which creates Earth’s magnetic field which deflects solar winds

6. Why was Earth unable to hold onto that first atmosphere?

Earth’s gravity is not strong enough to hold lighter gasses

7. What was the earth’s second atmosphere probably like, and what is it’s origin?

Produced by volcanic outgassing. (H2O, CO2, SO2, S2, Cl2, N2, and H2)

8. What is one scientific explanation for the origin of our oceans, and what is the evidence?

As the earth cooled, water produced from outgassing. Evidence is pillow basalts which are deep marine beds in greenstone belts

9. Why couldn’t there have been oceans during Earth’s earliest years?

Earth was horribly hot and violent.

10. What evidence is there that comets were not big contributors to the Earth’s oceans?

Cosmo Chemists found that comet Hale-Bopp contains substantial amounts of water. Comets that formed in the Kuiper Belt contains less amounts of water in a short period.

11. Describe two processes that produce oxygen in our planet?

Photochemical dissociation is the process where water molecules are broken up by ultraviolet radiation, and then the oxygen from the water molecules evaporate into the air.

Photosynthesis - CO2 + H2O C6H12O6+ O2 produced by cyanobacteria, and eventually higher plants – probably supplied the rest of O2 to atmosphere.

12. What processes consume oxygen on our planet?

Chemical weathering consumes oxygen through oxidation of surface materials, animal respiration, and burning of fossil fuels.

13. What evidence is there that the amount of O2 in the Earth’s atmosphere has increased over time?

Iron is highly reactive with oxygen, so we can look at the rocks oxidation state and learn more about the atmosphere evolution. These rocks are very common, but they do not form today.

14. If Earth’s CO2 was 1,000 times higher in the primordial atmosphere, where did it all go?

The H20 condensed into the oceans and then the CO2 dissolved into the oceans. The CO2 laten then precipitated out.

15. Why hasn't N2 (atmospheric nitrogen) changed like CO2 have?

The N2 is chemically inactive and stayed as a gas in the atmosphere and became dominant in its constitute.