GC 170 1st Edition Test 2 Study Guide Lectures 7 11 Lecture 7 Lecture 8 February 12th 17th Physical Causes of the Greenhouse effect Why do greenhouse gases absorb and emit longwave radiation e g what is it about their structure H2O CO2 are triatomic Highest concentration ppm in the atmosphere o They are greenhouse gases o Shortwave passes through o Longwave absorbed and emited Reaction In contrast why are most gases in the atmosphere N2 O2 not greenhouse gases N2 O2 are diatomic o They are not greenhouse gases o Shortwave passes through o Longwave passes through Which greenhouse gases have the highest concentrations in the troposphere H2O and CO2 What happens when the greenhouse gases absorb electromagnetic radiation The GHG s absorb energy o Causes vibration bending and rotation of atomic bonds o This process converts electromagnetic radiation to heat energy Electromagnetic radiation is transmitted as a wave and a stream of particles photons Photons interact with atoms and molecular bonds What is an absorption spectrum for a greenhouse gas Absorption spectrum the proportion of energy absorbed by a gas at a particular wavelength What does the absorption spectrum for the atmosphere represent think about the x y axes The blue area in an IR band how the atmosphere absorbs and emits longwave radiation Where does visible light pass through the atmosphere Ozone O3 o Absorbs most of incoming UV good thing o Ozone layer in the stratosphere o Ozone in the troposphere absorbs outgoing IR What is the atmospheric window Wavelength bands where no radiation is absorbed or emitted What would the temperature on earth be like if there was no greenhouse effect If there was no greenhouse gases all longwave radiation would be transmitted to space o Earth would be freezing Lecture 8 Lecture 9 February 17th 19th The Energy Budget What is Albedo Which surfaces have high albedo Which surfaces have low albedo Albedo o The fraction of sunlight energy that is reflected by a surface o Depends on the properties of the surface Dark land surfaces forested have an equal albedo to water Clouds They are bright white o High albedo and reflect incoming solar radiation clouds High albedo very reflective Low albedo low reflective Why do clouds have a dual role in the energy budget Clouds o They are bright white High albedo and reflect incoming solar radiation clouds Why is there more incoming solar radiation along the equator Because there is more radiation per unit square The sun emits waves towards the earth and it hits the equator and the energy is later redistributed What happens to incoming solar radiation four options Reflected o Clouds 23 o Surface 7 Absorbed o Surface 47 o By atmosphere UV 22 What happens to longwave radiation three options Radiated upwards Gas and clouds 58 Surface radiation radiated up 116 Radiated downwards 98 Passes through atmosphere 12 Why is it important to learn about the planetary energy balance and budget Humans are putting lots of CO2 into the atmosphere o Increases greenhouse effectcb 2 What is an example of changing one component of the energy budget Increased Greenhouse gases o Warmer Surface Temps Melting ice caps Increased absorption of solar radiation o Warmer Temperature o How does this affect the other components Warmer Surface Temps o Melting ice caps Increased absorption of solar radiation Warmer Temperature All interconnected o One change influences other parts of the system What contributes to the variation in surface temperature around the earth Incoming solar radiation based on earth s curvature Earth s reflectivity and cloud cover Albedo Warmth provided by the atmosphere What is a phase change Phase change the transition between different states o Liquid Solid Gas What is latent heat and sensible heat Latent Heat o Warming energy is absorbed making surroundings cooler Sensible heat o The temperature of something that can be felt How does convection contribute to heat transfer in the troposphere o Convection in the atmosphere Circulates heat around troposphere Air is warmed Becomes less dense and rises Cooler air sinks and replaces What happens to the environment when evaporation or condensation occurs Evaporation makes environment cooler water to warm environment Condensation water vapor transitions into water making the molecules slow down and release heat What happens if we add water to a desert environment Evaporation Lecture 10 February 24th Hadley Cell Circulation and the Jet Stream Understand what the Global Energy Distribution represents Why is there a surplus of energy at the equator Incoming radiation varies depending on latitude o Low high low o At the poles the radiation is spread over a larger area Less energy per unit area o Most radiation at the equator How is the surplus of heat energy at the equator transferred to the poles Outgoing radiation also varies but not nearly as much as incoming o Surplus of energy at the equator gets redistributed towards the north south If this did not happen the equator would be too hot and the poles would be freezing Weather and climate in troposphere have to do with redistribution global heat transfer from the equator to the poles What are the components and processes of Hadley Cell Circulation Hadley Cell circulation o Incoming solar radiation goes down towards earth o Heats up ocean and land o Warm air rises convection and uplift through humid air and water vapor o Convergence Area of low pressure at the surface surface winds move towards this area o Equator Intertropical Convergence zone o Divergence Cool air sinks from up in the troposphere Surface winds flow away at the surface which creates high pressure At areas of high pressure warm air diverges at the surface o Prevents condensation cloud formation o Environment becomes very dry desert o Polar Front zone Zone of converging air from equator and poles Very cold and dense air Air flows away from north pole Warm air rises up cool air sinks below warm air o Jet Stream Current of upper level winds moving west to east Pushes storms across the polar front Caused by strong temperature and pressure gradient in upper atmosphere Changing with warming temperatures How do convection and condensation contribute to heat transfer in the atmosphere Condensation releases heat to the environment gas liquid in cloud form o Warm air rises near equator convection o Water vapor condenses release heat o Warm air moves towards poles cooling in the process o Cool air sinks at 30