ABE-137-Greenhouse-Effect-GW.pdf

ABE 137: Hydrometeorology The Atmosphere, Greenhouse Effect and Global Warming What is the physical structure of the atmosphere? - multi-layered, with little chemical interaction - most of the mass is near the surface Atmospheric Pressure Decreases With Height...

ABE 137: Hydrometeorology The Atmosphere, Greenhouse Effect and Global Warming What is the physical structure of the atmosphere? - multi-layered, with little chemical interaction - most of the mass is near the surface Atmospheric Pressure Decreases With Height Above 99% Most of the energy is captured close to the Above 90% surface That energy Above 50% drives climate and weather Pressure (mb) 50 percent of mass of the atmosphere is within 6 km of the surface Structure of the Atmosphere Exosphere Thermosphere/Ionosphere Mesosphere (UV Rays, cosmic rays, meteors) (Ozone Maximum) Stratosphere Troposphere (most clouds, 4/5 of mass)) Temperature What is the chemical structure of the atmosphere? - nitrogen by far the most common element - oxygen is second most common - greenhouse gasses are small in amount, but important! 78% nitrogen 20.6% oxygen < 1% argon 0.4% water vapor 0.036% carbon dioxide traces gases: Ne, He, Kr, H, O3 Methane, Nitrous Oxide  The “Greenhouse Effect” The Earth’s surface receives energy from two sources: the sun & the atmosphere – As a result the Earth’s surface is ~33C warmer than it would be without an atmosphere Greenhouse gases are transparent to shortwave but absorb longwave radiation – Thus the atmosphere stores energy A schematic representation of the exchanges of energy between outer space, the Earth's atmosphere, and the Earth surface. The ability of the atmosphere to capture and recycle energy emitted by the Earth surface is the defining characteristic of the greenhouse effect. The greenhouse effect, discovered by Joseph Fourier in 1829 and first investigated quantitatively by Svante Arrhenius in 1896, is the process in which the emission of infrared radiation by the atmosphere warms a planet’s surface. The name comes from an analogy with the warming of air inside a greenhouse compared to the air outside the greenhouse. The Earth's average surface temperature is about 20-30°C warmer than it would be without the greenhouse effect. In addition to the Earth, and especially have greenhouse effects.  Known Greenhouse Gases ⚫ Carbon Dioxide (CO2) – Source: Fossil fuel burning, deforestation Anthropogenic increase: 30% Average atmospheric residence time: 500 years ⚫ Methane (CH4) – Source: Rice cultivation, cattle & sheep ranching, decay from landfills, mining Anthropogenic increase: 145% Average atmospheric residence time: 7-10 years ⚫ Nitrous oxide (N2O) – Source: Industry and agriculture (fertilizers) Anthropogenic increase: 15% Average atmospheric residence time: 140-190 years CFC’s, O3, H2O vapor The CO2 Cycle Sources: volcanism, metamorphism, respiration, fossil fuel burning, deforestation Sinks: photosynthesis, rock weathering, carbonate deposition, ocean adsorption Greenhouse Effect & Global Warming The “greenhouse effect” & global warming are not the same thing. – Global warming refers to a rise in the temperature of the surface of the earth An increase in the concentration of greenhouse gases leads to an increase in the the magnitude of the greenhouse effect. (Called enhanced greenhouse effect) – This results in global warming  Short-Term Climate Change Climate change over short time scales (