GC 170 1st EditionTest #2 Study Guide Lectures: 7 - 11Lecture 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 gaseso Shortwave passes througho Longwave absorbed and emited (Reaction)In contrast, why are most gases in the atmosphere (N2, O2) not greenhouse gases?-N2 & O2 are diatomico They are not greenhouse gaseso Shortwave passes througho Longwave passes throughWhich greenhouse gases have the highest concentrations in the troposphere? -H2O and CO2What happens when the greenhouse gases absorb electromagnetic radiation? -The GHG’s absorb energyo 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 bondsWhat is an absorption spectrum for a greenhouse gas? -Absorption spectrum: the proportion of energy absorbed by a gas at a particular wavelengthWhat 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 radiationWhere does visible light pass through the atmosphere? -Ozone (O3)o Absorbs most of incoming UV (good thing)o Ozone layer in the stratosphereo Ozone in the troposphere absorbs outgoing IRWhat 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 spaceo Earth would be freezingLecture 8 & Lecture 9 (February 17th & 19th): The Energy Budget What is Albedo? Which surfaces have high albedo? Which surfaces have low albedo? -Albedoo The fraction of sunlight (energy) that is reflected by a surfaceo 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 reflectiveWhy do clouds have a dual role in the energy budget? -Cloudso 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 re-distributedWhat happens to incoming solar radiation? (four options) -Reflectedo Clouds (23%)o Surface (7%)-Absorbedo 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 atmosphereo Increases greenhouse effectcb 2What is an example of changing one component of the energy budget? -Increased Greenhouse gaseso Warmer Surface TempsMelting ice caps-Increased absorption of solar radiationo Warmer TemperatureoHow does this affect the other components? -Warmer Surface Tempso Melting ice capsIncreased absorption of solar radiation-Warmer Temperature-All interconnectedo One change influences other parts of the systemWhat 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 atmosphereWhat is a phase change? -Phase change: the transition between different stateso LiquidSolidGasWhat is latent heat and sensible heat? -Latent Heato Warming energy is absorbed making surroundings cooler- Sensible heat: o The temperature of something that can be feltHow 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?- EvaporationLecture 10 (February 24th): Hadley Cell Circulation and the Jet StreamUnderstand what the Global Energy Distribution represents: Why is there a surplus of energy at the equator?-Incoming radiation varies depending on latitudeo Low  high  lowo At the poles, the radiation is spread over a larger area (Less energy per unit area)o Most radiation at the equatorHow is the surplus of heat energy at the equator transferred to the poles? -Outgoing radiation also varies but not nearly as much as incomingo 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 circulationo 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 vaporo Convergence: Area of low pressure at the surface (surface winds move towards this area)o Equator: Intertropical Convergence zoneo 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 surfaceo 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 airo 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 temperaturesHow do convection and condensation contribute to heat transfer in the atmosphere? -Condensation releases heat to the