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CU-Boulder GEOL 1060 - Unit I. The Earth System

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Unit I. The Earth SystemSystem- is an entity composed of diverse but interrelated partsthat function as a complex wholeComponents- the individual parts that function as a complex whole; part of a system (volume, mass) energy (heat, energy) attribute (temp, pressure) or a sub-systemFeedback- a process internal to a system that acts to either amplify or diminish change imposed externally; self-perpetuating mechanism of change and a response to that changePositive Feedback- amplifies a change in state; produces a dramatic changeExample: Snow meltingNegative Feedback- diminishes (or resists) a change in state; promotes stabilityExample: An increase in body temperature causing the body tosweatEquilibrium State- if the system is in equilibrium, it is not changing; it will not change unless the system is disturbedStable- negative feedback (refer back)Unstable- positive feedback (refer back)Perturbation- temporary disturbance to a system; less than a 100 yearsExample- Volcano, El Nino, La Nina, Seasonal HurricanesForcing- longer lived disturbance or change; more than a 100 yearsExample- The sunResponse Time- the temperature response to an increase in solar luminosity is a progression from one stable equilibrium state to the next. These equilibrium responses are the sum ofthe response that would occur without feedback plus the feedback effect itselfThreshold- a condition of a system in equilibrium (or undergoing slow change), that when exceeded results in a dramatic, non-linear behaviorSmall force applied resulting in a massive failureExample: Snow avalanche, Trees blown down after a while, a pencil snapping in halfUnit II. Global Energy Balance and the Greenhouse EffectElectromagnetic Radiation- self-propagating electric and magnetic waves; or radiation transmitted through the vacuum of space without a mediumWavelength- distance between two successive peaks or troughsRadiation moves at the speed of lightFrequency- the number of wave crests that pass each secondWavelength/Frequency = Speed of Light, 299 792 458 m/sShorter wavelength electromagnetic radiation has higher energy (temp.)Example: The Sun (hotter body)Longer wavelength electromagnetic radiation has less energy (temp.)Example: Earth (cooler body)Flux- the amount of energy that passes through a given area during a specific time period; the flux of energy decreases by the square of the distance from the source; measure it perpendicularExample: flux of solar radiation is the amount of energy per unit areaExample 2: water passing thru a gate in the Grand CanyonWhy are the poles colder than the tropics?-Poles are farther from the sun-The flux radiation is smallerBlackbody- object that emits/absorbs electromagnetic radiation with 100% efficiency at all wavelengthsExample: Earth, Sun, People absorb sunAlbedo- the reflectivity of a surfaceIf no sunlight reflects, albedo = 0Example: Roads absorb the sun (hot)Example 2: Ocean (.05)Example 3: Black Roof (0)If all sunlight reflected, albedo = 1Example: Sidewalk reflects sun (keeps cool)Example 2: Snow (.85)Example 3: Bare Ground (.4)The flux of solar radiation to Earth depends on:-Earths distance from the SunEarths temperature depends on four factors:1. Sun’s Temperature (T^4) – multiplier effect2. Distance from the sun (D^2)3. Albedo4. Greenhouse GasesTemperature- a measure of the degree of relative hotness or coldness of a body or environment; a measurement of its molecular activity: the faster molecules are moving, the hotter the medium. When there is no molecular motion, it can get no colder: absolute zeroHeat Transfer MechanismsRadiation: process in which energetic particles or energetic waves travel through a medium or spaceConduction: the transfer of heat energy by direct contact between molecules; plays little role in atmosphere or oceanic heat transferConvection: process in which heat energy is transported by the motions of a fluid; heat transfer by mass motion of a fluid such as air or water when heatedfluid is caused to move away from the source of heat; carrying energy troposphere is convective because roughly ½ the incoming sunlight is absorbed by the ground and ocean surfaceLatent Heat- is the heat energy gained or released in the transition from one phase to another (gas – liquid – solid: releasing energy into the surrounding area) Example: clouds release energy(solid-liquid-gas: consumes energy)Example: Ice to water to vapor (takes energy to heat up and change phase)Sensible Heat- is measured directly by temperature (the speed at which molecules are moving)Greenhouse Gas (GHG)- gases that are transparent to shortwave solar radiation,but absorb certain wavelengths of Earths longwave radiation; any of the atmospheric gases that contribute to the greenhouse effect by absorbing infrared radiation produced by solar warming of the Earth’s surface. They are selective absorbers.Greenhouse Effect- the ability of the atmosphere to capture and recycle energy emitted by the Earth surfaceResidence Time- life span of a molecule; Water vapor (H20v) has a short life span of weeks. Carbon Dioxide (CO2) long residence time of 100years. Methane 15years.Dominate Greenhouse Gases in the Atmosphere-Nitrogen (N2)-Oxygen (O2)-Argon (AR)-Water Vapor (H2O)-Carbon Dioxide (CO2)4 Dominant Greenhouse Gases Ranked in order of importance:1. Water Vapor2. Carbon Dioxide (CO2)3. Methane (CH4)4. Nitrous Oxide (NO2)Some greenhouse gases are more effective because there are “windows” where there is little or no absorbance Greenhouse gases that absorb in these windows are more effective, molecule for molecule, than additional H20 or CO2 molecules. In addition, some light and wavelengths absorb differently in the (ER) electromagnetic radiation.Unit III. Circulation of the Gaseous EarthAtmospheric Pressure- total mass of stuff; with more heat there are fewer molecules per unit area, less denseAtmospheric Temperature- is a measure of temperature at different levels of theEarth's atmosphere. It is governed by many factors, including incoming solar radiation, humidity and altitude.Relative Humidity- fraction of water vapor in a parcel of air compared to its maximum capacityWarm air holds more water vapor than cold airAbsolute Humidity- the actual mass of water vapor in a given mass of airTroposphere- weather happens: clouds, rain, snow and storm activity; mixed convectionTropopause- unstable (always moving) mixed because heated from the bottomStratosphere- helium can go to the stratosphere (not well


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