GPH 212, Exam #1 Study Guide
GPH 212, Exam #1 Study Guide GPH 212
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This 17 page Study Guide was uploaded by Sheridan Smede on Friday September 16, 2016. The Study Guide belongs to GPH 212 at Arizona State University taught by Matei Georgescu in Fall 2016. Since its upload, it has received 69 views. For similar materials see Introduction to Meteorology in Physical Geography at Arizona State University.
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Date Created: 09/16/16
Exam #1 Study Guide Introduction to Meteorology ● The atmosphere ○ Mixture of gas molecules ■ Small suspended particles of solid and liquid and falling precipitation ● Meteorology ○ Study of atmosphere ○ The process we call “weather” ○ Weather shortterm ○ Climate = longterm ○ Basically everything you “see in the sky” ○ We are interested in the mechanisms of weather, not just the way it looks ○ or feels ■ Not “it is hot today”, but what are the processes that led to it being ■ hot? ○ Climatology ■ Long term study of the atmosphere ■ Statistics key element of climate (average temperature, frequency of ■ extreme heat, etc.) ■ Not just about averages, but the deviation from the average ■ Climatology is about the variability of climate ○ Where is the distinction between climate and weather? ■ Literal definition: A process becomes climatic if it lasts 30 years or longer ■ In this class: Weather typically lasts less than a week ■ Very much shortterm ■ Over longer periods of time ○ Climate begs the question: “What leads to variability?” ○ Earth System ■ Atmosphere ■ The way that air moves (atmospheric motion) ■ Incoming amount of solar radiation ■ How air is received and reemitted ■ Regulation and transfer of material (plant cycle) ■ Atmosphere is not unaffected by what goes on below the surface ■ Changes in parts of the earth will still affect the atmosphere ■ External forcing mechanisms ■ These are the no natural forces on earth (a sauna, for example) ■ Human activities it all boils down to our use of energy ■ Unsustainable ■ Climate has a natural variability (depends on many things) ■ Anthropogenic climate change ■ Correct term for human effect on planet evolution ■ Refer to video: http://video.nationalgeographic.com/video /sci ■ ence/earthsci/climateweathersci/ ■ Air quality ■ Droughts ■ Crop failure ■ Increase in cost of produce ■ Everything is interrelated ■ Aviation perspective when a haboob arrives ■ Cannot see ■ Creates problem for pilots ■ Strong winds ■ Volcanoes modify temperature of air rising from earth ■ Volcanoes emit sulfates, solid particles, etc. ■ Strength of eruption determines how high they go ■ Residence time (time spent in atmosphere) will be shorter the less intense the explosion is ○ Lithosphere ○ Biosphere ○ Hydrosphere ○ Stratosphere ■ Very stable ■ Particles emitted into stratosphere stay for a very long time ■ Mount Pinatubo particles stayed in stratosphere for several years ■ Made the regions nearby cool down ■ Particles from volcano prevent solar radiation reaching ■ surface ● Between 1980 and 2010 99 disasters occurred ○ $700B in damage ● Invention of air conditioner ○ Phoenix population skyrockets ○ Deserts are fastest growing urban areas in the world ○ Humans are adaptable ● Thickness of the atmosphere ○ Atmosphere density decreases rapidly with height ○ Top of the atmosphere is undefined ○ Majority of atmospheric mass is contained in thin layer near earth’s ○ surface ○ Atmosphere contains impressive sum of mass ○ Atmosphere characterized differently by different scientific domains ● “Where does the atmosphere end?” ○ There is no actual end ○ Goes toward zero ○ Meteorological perspective: atmosphere is not infinite ○ Top of atmosphere is “undefined” ● Vertical structure of atmosphere ○ Thermal layers of the atmosphere ■ 4 distinct layers based on average temperature and how temperature changes as one moves vertically ■ Starting from the bottom: ■ Troposphere : where most of the action happens ■ Tropo (Greek root) means “turning” ■ Lowest layer ■ Region promotes atmospheric overturning (always in ■ movement both vertical and horizontal) ■ Layer of almost all weather processes ■ Warmed at surface by solar radiation ■ Steady temperature decrease with height ■ Thinnest layer but contains 80% of atmosphere’s mass ■ Thermal expansion ■ Tropopause is 16 km over the tropics, but only 8 km at poles ■ Atmosphere is quite transparent to incoming solar radiation ■ An open porous medium for solar radiation to traverse through ■ This is where most clouds exist ■ Sometimes, violent updrafts penetrate cloud tops into stratosphere ● Stratosphere: area of little weather and temperature increases with height ○ Contains 20% of all atmospheric mass ○ Why does temperature increase instead of decrease like troposphere? ○ Inversion (increasing temperature with height) is caused by absorption of ultraviolet radiation by ozone ○ Ozone exists through an altitude between 2030 km ● Mesosphere: temperature decreases with height ○ Coldest atmospheric layer 0 km above surface) ● Thermosphere: uppermost layer, slowly merges with interplanetary space ○ Increasing temperatures with height ○ Temperature approaches 1500 Celsius ○ Both mesosphere and thermosphere combined account for 0.1% of total atmospheric mass ● Permanent Gases ○ N2, O2, Ar, Ne, He, Kr, Xe, H2 ○ Nitrogen makes up most of our atmosphere ● Variable Gases ○ H2O is water vapor ■ Most important variable gas ■ Clouds, rain, snow, irrigating crops, having food to eat ○ CO2 is carbon dioxide ■ We put more of this in the atmosphere everyday, which means it is constantly changing and is variable ○ O3 is ozone ■ Harmful to humans, an irritant to the lungs ■ The TwoFace of meteorology ■ Has both positive and negative effects ■ In stratosphere: good ■ In troposphere: bad Weather Resources ● weather.gov ○ Shows current temperature ○ Shows dew point ● Relative humidity (moisture index) is a different metric to use for moisture ● Dew point means saturation will occur when current temperature drops to [dew point temperature] ○ Higher the dew point, more moisture in the atmosphere ○ Lower the dew point, the drier it is ○ You should look at maximum and minimum recorded values for ○ certain days ■ Click on city, get detailed notes on weather for given region ■ Detailed pi oint current conditions and forecast ■ City map (by Google) ■ Radar and satellite imagery ■ Hourly forecast ■ Site description (latitude and longitude) ■ Probability of precipitation ■ Weather forecasts are not always correct and can change based on many factors ■ (microclimatic changes) Weather Jargon ● First Order Weather Stations ○ K(3 letters) such as “KFAT” ○ KFAT = weather station at Fresno ○ Normals ■ Temperature based on 30 ear average ○ Records ■ Highest and lowest temperature for any given day ○ Radar ■ Shows movement of winds and weather and their progression of movement over time ○ Weather graphs (hourly) will show: ■ Temperature: ■ Dew point ■ Gusts (mph) ■ Winds (mph) ■ Wind direction (wind bars) ■ Relative humidity ■ Precipitation potential ■ Sky cover Composition of the Atmosphere ● Unlike CO2, water vapor is not transferred homogeneously ● Water vapor is the most important greenhouse gas ● Variable gas water vapor ○ Most abundant variable gas ○ Added and removed from atmosphere through hydrologic cycle ○ Concentrations exist from nearly 0% over desert and polar region to nearly ○ 4% near tropics ■ Never truly 0%, there is always at least a minuscule amount ○ Water vapor is a contributor to earth’s energy balance and atmospheric processes ○ Different types of precipitation ■ Snow, rain, sleet, etc. ■ During these cycles (water changing from one state to another), energy is either required or used for the process ■ Redistribution of energy ■ Looking at water vapor? ■ Use satellite imagery ■ Visible light spectrum (ROYGBIV) ■ To see clouds during daytime, not as useful during the night ■ At this point, use Infrared (different part of light spectrum) ■ Carbon Dioxide ■ Trace gas accounting for 0.04% of the atmosphere’s volume (400 ppm) ■ Much less in atmosphere compared to water vapor ■ Important to earth’s energy balance ■ Added through biologic respiration, volcanic activity, decay, and natural ■ and human related combustion ■ Incomplete combustion of fossil fuels ■ Removed through hotosynthesis ■ Process whereby plants convert light energy to chemical energy ■ Needed : light, water, carbon dioxide ■ On our planet: steady increase of carbon dioxide in the atmosphere ■ Longest record of this is kept in Hawaii ■ In this graph, we see seasonal cycle ■ In winter: upward trend ■ In summer: downward trend ■ Plants are using CO2 ■ Redistributing it into their root system Knowledge Check 1. Nearly all of the atmosphere lies below an altitude of 100km. As a percentage of earth size, how thick is this layer? About 2% ● Radius of earth is approximately 6400 km (4000 miles) ● Divide this by 100 km (altitude of atmosphere) 2. Why are horizontal motions stronger than vertical motions within our atmosphere? Atmosphere has much more surface area than height. Storms, rain, and snow are due to vertical motions. Compare atmosphere to skin of an apple. 3. What is the difference between meteorology and climatology? Climatology is longterm effects, meteorology is shortterm Carbon Dioxide ● Presence in atmosphere has slowly increased over time (though it does decrease in the summer time) ● Half is absorbed, half stays in atmosphere Carbon monoxide harmful to plants, animals, and humans ● Urban areas typically have higher concentration of CO2 ● Ozone precursors : O and O2 once you add sunlight you get ozone Ozone ● The triatomic form of oxygen and is essential to life on Earth (O3) ● Near the surface (~.15. 2 ppm) is a pollutant ● In the stratosphere (~1520 ppm) it is an essential absorber of UV radiation ○ Ultraviolet radiation is harmful to living organisms ● Chlorofluorocarbons (CFCs), specifically atoms of chlorine, react with ozone in stratosphere and destroys the ozone ● Created the ozone hole above Antarctica ● Because extremely cold temperatures are required to create CFCs ● The temperature creates unique clouds that interact with chlorine and eventually break up the ozone ● One chlorine molecule can destroy thousands on ozone molecules ● The ozone hole is getting smaller ● 80% over both poles is human generated ○ Ozone is the earth’s “sunscreen”, protecting the earth from UV radiation ○ Ozone is measured in Dobson units ● Ingredients for Ozone hole ○ Large concentration of Cl ○ Cold temperatures (required for formation of “polar stratospheric clouds” which promotes Cl production in a form where it is ready to destroy ozone) ○ Sunlight (to drive chemical reactions) Methane ● A variable gas in small but (recently) increasing concentrations ● Released to the atmosphere through fossil fuel activities, livestock digestion, and agriculture cultivation (especially rice) ● Works as an effective absorber of terrestrial radiation and plays an active role in near surface warming ● In essence, “the greenhouse effect” Aerosols ● Any solid or liquid particle (other than water) which exists in the atmosphere ○ Also called particulate ● Both natural (sea spray, dust, combustion, volcanic activity) and human (combustion) produced products ● Due to small size, remains suspended for long periods of time ● Contribute to precipitation processes as condensation nuclei ● Without these, we wouldn’t have rain ● Serves as host for cloud formation Density ● Defined as mass (kg) per unit volume (m^3) ● Due to compressibility, near surface air is more dense than that above ● As you move upwards, atmosphere becomes less dense ● At sea level, air densit .2 kg m^3 ○ Mean free path ■ Average distance a molecule travels before colliding with another molecule ■ A lot less when close to surface; a lot more farther away ○ Not moving ○ Fronts move at different speeds ○ Precipitation is common along fronts, so when a front approaches it is not unusual to have rain or snow in addition to a change in temperature ○ Intensity of precipitation varies ○ When fronts meet, one air mass dominates (for example, if the warm air becomes dominant, it is a warm front) ○ After a cold front departs, there is often very sunny and clear weather Temperature Scales ● Gabriel Fahrenheit ○ 212 degrees F = boiling point ○ 32 degrees F = freezing point ● Anders Celsius ○ 100 degrees C = boiling point ○ 0 degrees C = freezing point ○ Celsius > Fahrenheit ○ F only used in America ● F = 9/5 C +32 ● C = 5/9(F32) ● To overcome shortcoming of negative values, the Kelvin scale was introduced ● Didn’t make sense that temperature could have a negative value ○ K = C +273.15 ○ 373.15 K = boiling point ○ 273.15 K = freezing point ○ An increment of Kelvin change is identical to an increment of Celsius Change ● Absolute zero ○ 460 F ○ 273 C ○ 0 K ● Celsius degree is 1.8 more than Fahrenheit degree ● 0 Kelvin = all motions stop (absolute zero) ● Adding 10 degrees Celsius = adding 18 degrees Fahrenheit ● 104 F = 40 C ● 86 F = 30 C Meteorological History ● When were these scales developed? ○ Galileo Galilei (1593) first thermometer prototype (thermoscope) ■ Lacked a numerical value to indicate temperature ● Evangelista Torricelli (1643) invented device to measure air pressure (barometer) ● Joseph Louis Ga Lussac (French chemist/physicist) ○ GayLussac Law advanced our understanding of gases and atoms ○ Traveled several thousand feet in a hot air balloon; collected air to analyze ○ Went on a solo flight 40k feet in the air ○ Expansion and contraction of our atmosphere GayLussac Law ● When you add heat, air expands ● After air expands, pressure is lost ● Air molecules will begin to leave vessel they are in ● Eventually, vessel will reach equilibrium ● Higher pressure = outside the vessel ● Lower pressure = inside the vessel, compared to outside the vessel ● Air moves in response to pressure imbalances ● Air will move from high to low pressures History Cont. ● Joseph Henry helped purchase meteorological instrumentation to establish an observational network ○ “Programme of Organization” ○ Goal was to solve problem of American storms ○ Around the same time, telegraph was invented Is it possible a librarian will discover a temperature record going back to the middle ages? ● No, they did not have a way to measure temperature back then Energy ● Defined as anything that has the ability to do work ○ Agent capable of setting an object in motion ○ Agent capable of warming a teapot ○ SI unit of energy Joule [kg*m^2/s^2] ● Simplest of activities require a transfer of energy (for example, looking at and writing these words) ● One two billionth of the energy emitted by the sun is transferred to earth as electromagnetic radiation ○ Some ER is absorbed by atmosphere and some by the earth’s surface Kinds of energy ● Kinetic ○ Energy in use or in motion ○ Ex: light, radiation, heat, motion, electrical power ● Potential ○ Energy in reserve or stored ○ Ex: reservoir behind dam, high pressure ● Chemical potential energy ○ Ex: battery, gasoline, explosives, firewood, food ● Food ○ Process of metabolism is used to convert potential energy stored within food to kinetic energy Gravitational potential energy ● Object’s placement ● A falling raindrop has both kinetic and potential energy Model output statistics (MOS) ● A technique that interprets numerical weather prediction (NWP) output to produce site specific guidance (weather information the public depends on for daily activities) ○ 9 million regression equations ○ 75 million forecasts per day ○ 1200 products sent daily ○ 400k lines of cost (mostly FORTRAN) ○ Millions of hours of supercomputer time ○ MOS involves historically tracking how a forecast model performs compared to real observed records ○ Used to improve forecast accuracy ○ Cooling leads to contraction ○ Heating leads to expansion ○ Add value to NWP model to quantify uncertainty MOS ● Advantages: ○ Reliable probabilities ○ Removal of some systematic model bias ○ Specific element and site forecasts ● Disadvantages: ○ Changing NWP models (ex: numerical models themselves are always modified) ○ Availability and quality of observations MOS What is needed? ■ Historical weather output ■ Observations ● Compare data to what actually happened Reading an MOS message (interpretation goes from top to bottom of message): ● Starts with identifier of location ● Always 4 letters, starts with K (ex: KDEN, KSEA, KPHX) ● GFS a numerical weather prediction model ● MOS guidance the title ○ Guidance = prediction ○ Because meteorology is an inexact science ● Valid date for forecast ● 1200 UTC coordination of time globally ○ Greenwich where we base time globally ● DT the date ○ A short term prediction, not more than four days ● Values by hour ● N/X Nighttime minimum temperature and daytime maximum temperature ● TMP temperature at designated hour ○ Every three hours ○ Some metrics provided every 6 hours ○ Once you reach 00 (midnight) the day changes ● DPT dew point at designated hour ● Dew point = the temperature current temp needs to drop to in order for saturation to occur ● Dew point cannot be higher than actual temperature ● CLD cloud conditions; coverage ○ OV overcast ○ BK broken ○ Clear ○ SC scattered clouds ● WDR wind direction (in tens of degrees) ○ Ex: 19 = 190 degrees ○ 180 degrees = wind is coming from the south ○ 90 degrees = coming from the east ○ 270 degrees = coming from the west ● WSP wind speed, given in units of knots ● P06 probability of precipitation for 6 hours previous ● P12 probability of precipitation for 12 hours previous Characteristics of Radiation ● Intensity and wavelengths of emitted radiation ● Categorized into a few individual “bands” along the electromagnetic Spectrum ● Electromagnetic radiation ○ Visible light (VIS) is a narrow band bound by infrared (IR) and ultraviolet (UV) ○ Xray radiation has very short wavelengths and can penetrate soft tissues ○ Wavelengths typically specified in micrometers ○ From short to long wavelengths: ■ Gamma rays > xrays > ultraviolet > visible light > Infrared > Radio waves ■ Longer wavelengths = less harmless to humans ■ Wave lense distance between peaks of waves ● All matter radiates energy over a wide range of electromagnetic wavelengths ● Physical laws defining amount and wavelength of emitted energy apply to hypothetical perfect emitters of radiation known as blackbodies ● The earth and sun are similar to blackbodies ● Absorbs and emits maximum amounts of radiation ● Energy radiated by substances occurs over a wide range of wavelengths ● Shape of curve of intensity of emitted radiation is similar ● Peak of the curve (for earth) corresponds to a longer wavelength StefanBoltzmann Law ● Single most important factor that determines how much energy a blackbody radiates is its temperature ● The intensity of radiation depends on the temperature raised to the fourth power ● StefanBoltzmann law: ● Surface of sun is 5800 K (5500 C or 9900 F) and emits about 64 million watts per square meter ● Surface of earth is 288K ● StefanBoltzmann constant (5.67E8Wm K^4) Emissivity ● Percentage of energy radiated by a substance relative to that of a blackbody ● Radiation intensity in real objects (not blackbodies) is a function of both emissivity and temperature ● The graybody version of StefanBoltzmann law Shortwave/Longwave radiation ● For any radiating body, the wavelength of peak emission is gveien’s law ○ Lambda (Greek) used as constant 2898/T ● Warmer objects radiate energy at shorter wavelengths than do cooler bodies ● Wavelengths less than 4 micrometers are considered shortwave radiation ● Wavelengths more than 4 micrometers are considered longwave radiation ● Warmer bodies radiate more energy than do cooler bodies at all wavelengths Questions for upcoming exam: ● T/F s the earth is a perfect blackbody? ○ False ● Where does most weather occur in the atmosphere? ○ Troposphere ● What is the most common gas in our atmosphere? ○ Nitrogen ● Where is the ozone located in our atmosphere? ○ Stratosphere
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