Topic 6.1 Flashcards
The atmosphere as a dynamic system
The atmosphere, with inputs, outputs, flows, and storages, has undergone changes throughout geological time. It is a complex system impacting and being impacted by biotic components.
Composition of Earth’s atmosphere
Predominantly nitrogen (78%) and oxygen (21%), with small amounts of carbon dioxide, argon, water vapor, and other trace gases.
Human impact on atmospheric composition
Human activities like burning fossil fuels and deforestation alter the atmospheric composition, impacting the concentrations of gases like ozone, carbon dioxide, and water vapor, thus affecting ecosystems.
Layers of the Atmosphere
- Troposphere (0–10 km): The lowest layer, where most weather phenomena occur. Temperature decreases with altitude.
- Stratosphere (10–50 km): Contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. Temperature increases with altitude due to ozone absorption of UV radiation.
- Mesosphere (50–85 km): Temperatures decrease with altitude. Meteors burn up in this layer.
- Thermosphere (85–600 km): Temperature increases with altitude. The air is thin, and the region is where the auroras occur.
- Exosphere (above 600 km): The outermost layer. Air is extremely thin, and this is where the atmosphere merges into space.
The Greenhouse Effect
A natural phenomenon where the atmosphere traps heat, maintaining suitable temperatures for life. It acts like a blanket, slowing the loss of heat to space.
The Albedo Effect
A measure of reflectivity. Light colors reflect more radiation than dark colors, affecting the amount of solar radiation absorbed by Earth and thus influencing global temperature.
Role of Clouds in Albedo Effect
Clouds play a crucial role in the albedo effect. Daytime clouds reflect incoming shortwave radiation, cooling the lower troposphere, while nighttime clouds trap longwave radiation, warming it.
Importance of the Atmosphere
Provides protection from harmful radiation, stabilizes climate, and is essential for processes like breathing and photosynthesis.
Specific Human Activities Affecting Atmospheric Composition
Industrial processes, agriculture, and transportation significantly alter atmospheric composition, leading to increased greenhouse gases and pollutants.
What are Chlorofluorocarbons (CFCs)?
CFCs are man-made chemical compounds containing chlorine, fluorine, and carbon. Once widely used in refrigeration, air conditioning, and aerosol sprays, they are significant contributors to ozone layer depletion.
Due to their ability to break down ozone molecules in the stratosphere, international efforts like the Montreal Protocol have phased out their use.
Types and Impacts of Atmospheric Pollutants
Key pollutants include sulfur dioxide and nitrogen oxides, originating from sources like vehicles and factories, causing health issues and environmental damage.
Causes and Consequences of Ozone Depletion
Primarily caused by CFCs, ozone layer depletion increases UV radiation reaching Earth, affecting health and ecosystems; addressed globally by the Montreal Protocol.
What is the Composition of Earth’s Atmosphere?
Earth’s atmosphere is composed primarily of nitrogen (about 78%) and oxygen (about 21%). The remaining 1% consists of argon (0.93%), carbon dioxide (0.04%), and trace amounts of other gases such as neon, helium, methane, krypton, and hydrogen. Water vapor also varies in concentration but plays a significant role in weather and climate.
