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# Scientific Education - SVT ## Chapter 1 **Introduction:** * 4.6 Billion years ago, the atmosphere comprised primarily of N2, CO2, H2O * The composition was roughly 70% N2, 21% O2, and traces of other gases (CO2, CH4, N2O). **Surface Cooling and Formation of the Atmosphere:** * Cooling of the...

# Scientific Education - SVT ## Chapter 1 **Introduction:** * 4.6 Billion years ago, the atmosphere comprised primarily of N2, CO2, H2O * The composition was roughly 70% N2, 21% O2, and traces of other gases (CO2, CH4, N2O). **Surface Cooling and Formation of the Atmosphere:** * Cooling of the planet's surface led to the liquefaction of water vapor. * Water vapor contributed to the initial atmosphere. **Early Life and Photosynthesis:** * The first traces of bacteria (3.5 billion years ago) exhibited photosynthesis. * Photosynthesis contributed to the oxygenation of the atmosphere. * This happened roughly 2.4 billion years ago. **Atmosphere-Biosphere Interactions:** * Interactions between the biosphere and atmosphere led to modifications in biodiversity. * Sources and sinks of atmospheric oxygen influenced various species. * Respiration and combustion are modern sources of oxygen and CO2 emissions. **Ozone Layer and UV Protection** * The ozone layer absorbs ultraviolet radiation. * Protecting living organisms from the damaging effects of UV rays. * Ozone formation from dissociation of O2 caused by UV rays **Conclusion:** * The planet's formation was concurrent with the Sun and other planets in the solar system. * Variations in temperature played a key role in the development of the liquid water surface and the hydrosphere. * Factors such as solar and geological activity (ex. solar flares, tectonic activity) , and radiation from the Sun, likely played a significant role in the emergence of life and its metabolic processes.