Unit 3 Part 1 Atmospheric Composition & Structure PDF

Atmospheric Composition & Structure Part 1  Objectives Understand the atmospheric composition and the effects of greenhouse gases. Understand how greenhouse gases contribute to climate change. Understand why O2 and N2 are not greenhouse gases. Under...

Atmospheric Composition & Structure Part 1  Objectives Understand the atmospheric composition and the effects of greenhouse gases. Understand how greenhouse gases contribute to climate change. Understand why O2 and N2 are not greenhouse gases. Understand how atmospheric pressure and temperature varies with altitude.  Composition Understanding the composition and the structure of the atmosphere makes you understand the effects of green house gases in more details. Major atmospheric components and their concentration: Loading… Atmospheric Components Concentration % Nitrogen N2 78 % Oxygen O2 21% Argon Ar 0.9 % Carbon Dioxide CO2 0.039% Water vapor H2O (Tropics) 4% Water Vapor (South pole) 0.00001 %  Composition N2, O2 and Ar are the most abundant components of the earth’s atmosphere. Nitrogen is an unreactive gas but when It splits into atoms it plays important roles in biological cycles. Oxygen is highly reactive is an essential for all living things. Argon is chemically unreactive. They are not greenhouse gases and they don’t cause climate change. The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into various chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. Loading… The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. Conversion of nitrogen into Plants absorb nitrogen from the soil in the form of nitrate nitrates and nitrites through (NO3−) and ammonium (NH4+). In aerobic soils atmospheric, industrial and where nitrification can occur, nitrate is usually the biological processes is called as predominant form of available nitrogen that is absorbed. nitrogen fixation. When a plant or animal dies or an animal expels waste, the The conversion of ammonium to nitrate is initial form of nitrogen is organic. Bacteria or fungi convert the performed primarily by soil-living bacteria and organic nitrogen within the remains back other nitrifying bacteria. into ammonium (NH+4), a process called ammonification or mineralization.  Composition CO2 and H2O “water vapor” are strong greenhouse gases. Minor components that affect the climate: Methane, nitrous oxide, ozone, freons > even though they are low in concentration they are very important greenhouse gases “most important causes of global worming” Greenhouse gases Concentration ppm Water Vapor, (South Pole) 0.1 ppm Water Vapor, ( Tropics) 40,000 ppm Carbon Dioxide 390 ppm Methane 1.7 ppm Nitrous Oxide 0.3 ppm Ozone at the surface 0.01 ppm Freon- 11 0.00026 ppm Freon- 12 0.00048 ppm  Greenhouse Gases The greenhouse effect is the problem caused by increased quantities of gases such as carbon dioxide in the air. These gases trap the heat from the sun, and cause a gradual rise in the temperature of the Earth's atmosphere A term used to describe the heating of the atmosphere owing to the presence of carbon dioxide and other gases. Without the presence of these gases, heat from the sun would return to space in the form of Infrared radiation. Loading…  Structure Structures of the atmospheric pressure and temperature influence climate and radiation budget. Both Pressure and Temperature varies with altitude.  Pressure with altitude Pressure is the force per unit area produced by a gas or liquid when it is in contact with a surface. At higher levels of the atmosphere the pressure decrease. This what makes your ears pop in an airplane. This decrease by altitude follows the barometric law, which states that atmospheric pressure decrease for every 16 km above the surface. The barometric Law, is a formula used to model how the pressure of the air changes with altitude. The pressure drops approximately by 11.3 Pa per meter in first 1000 meters above sea level. Barometer is a device used to measure the atmospheric pressure. This graph shows how pressure changes with altitude, as the height increase the pressure is decreasing.  Temperature with altitude. Layers of the atmosphere: 1. Troposphere 2. Stratosphere 3. Mesosphere 4. Thermosphere.  Temperature with altitude. Atmospheric Temperature layer with altitude Troposphere Decrease Stratosphere Increase Mesosphere Decrease Thermosphere Increase  The Vertical Temperature Profile The high temperature near the ground are caused by the absorption of sunlight at Earth’s surface. The heating rate is highest in the upper stratosphere near 50 km because more UV radiation is available. Above 50km, both the ozone concentration and the heating rate decline so the temperature decease with altitude in the mesosphere. The heat increase in the thermosphere because oxygen molecules are absorbing short-wavelength UV radiation. Atmospheric layer Temperature with altitude Troposphere Decrease Stratosphere Increase Mesosphere Decrease  Thermosphere Increase Layers of the atmosphere- Includes temperature and atmospheric pressure https://www.youtube.com/watch?v=IWJclb0_5-8 Troposphere  Troposphere The troposphere is important to climate studies, it’s where clouds, snow, rain and storms occur. The troposphere is different than other layers in the fact that it’s mixed by convection. The troposphere and the stratosphere are the outermost layers.  Stratosphere The pressure In the stratosphere is low. Contains most of the Earth’s ozone. Air in the stratosphere is very dry, it contains less than 5ppm of water vapor that’s why it lacks clouds, rain, and snow. However, polar stratospheric clouds can form in polar region during winter. Polar stratospheric clouds (PSCs) are clouds that form when water vapor enters the stratosphere and when temperatures are cold enough for water vapor to condense there. polar stratospheric clouds (pscs) Aurora Borealis: Northern Lights Aurora Australis: Southern Lights https://www.youtube.com/watch?v=OZ5idaNCIgA