AOSC 200-Atmos.umd.edu/~hudson/-Website username: aosc200, password: aosc200fo9-Videos about Montreal ice storm and Hurricane IreneWEATHER vs. CLIMATEWeather: instantaneous description of what atmosphere is doing at a particular timeand placeClimate: Description of what weather is usually like in region (not just average weather, description of extremes, too). -Why do different hemispheres have different weather?-Different ratios of land to oceans-Oceans tend to heat up and cool down more slowly than land does-Mountains cause instabilities in airflow, southern hemisphere is calmer (That and the ocean stuff is why S hemisphere is generally better weather)-Warm front- warm air mass flows over cold air mass (produces light rain)-Cold front- cold air mass flows under warm air mass (produces heavy rain, warm air is forced up very rapidly)Discussion Section (1/30)Weather- shorter timescales - What’s happening today?Climate- time/region averaged weather - Understanding ExtremesDIFFERENCES BETWEEN NORTHERN AND SOUTHERN HEMISPHERES-70% of land is in North-Mostly water in the Southern (82% water and 18% land)-Ocean acts as a thermostat and keeps seasonal difference (in summer and winter) less extreme in Southern hemisphere-Presence of tall and wide mountain ranges in the North affect the flow of air and cause great stipulations in temperature and climate patterns-Can sail all the way around globe on Southern Ocean without hitting land; this means there’s less friction for the air to come in contact with and weather is rougherover that area (Southern Ocean, right above South Pole) PRESSURE(Low pressure on weather map indicated with L)-When there’s low pressure Clouds, storms, winds move counterclockwiseColdfront: Blue (on map) moving downwards and SoutheastWarmfront: Red (on map) moving from NortheastSo basically when a low-pressure system comes through, a warm front will hit followed by a Coldfront and heavy winds-Behind the warmfront and ahead of the Coldfront is heavy rain, whereas behind theColdfront and in front of the warmfront is light rain (see first page of notebook for image)ATMOSPHERIC COMPOSITION-Molecular oxygen and nitrogen compose more than 99%-Of remaining 1%, 97% is Argon-Of the remaining, 93% of it is carbon dioxide-All remaining gasses are known as trace species; these control chemistry of atmosphereATMOSPHERIC EVOLUTION-Early atmosphere consisted of Hydrogen (H), Helium (He), Methane (CH4), and Ammonia (NH3)-As earth cooled, volcanic eruptions emitted water vapor (H2O), CO2, and nitrogen (N2)-Graph shows levels of CO2 in relation to time, and is an increase over time as well asa fluctuation during each year-The reason for this (a maximum amount of CO2 in the atmosphere during Spring and a minimum in Fall) is that since during the winter/beginning of spring there areno plants to take in CO2, there is more floating around in the atmosphere. However, as the plants grow and take it in, by the beginning of fall there is less CO2 floating around out thereExample of Atmospheric CO2 (Figure from lecture slides 2)-Volcano releases it into atmosphere-Dissolves in ocean-Plants photosynthesize -When we cut down forests, we’re releasing CO2 into atmosphereHYDROLIC CYCLE-Rain falls into ocean and stuff which evaporate back up into clouds-Rain falls on land (mountain); flows via river back into ocean and evaporate back toclouds-Also, water on trees transpire back into clouds-All driven by energy from the sunOTHER IMPORTANT GASES-Methane CH4: produced when plant material decays below water : Is greenhouse gas, long lifetime in Troposphere but breaks down in Stratosphere to form water-Chlorofluorocarbons: greenhouse gases, break down in Stratosphere, responsibleFor Ozone Hole (CFCs)-Banned emitting CFC’s into the atmosphere (in US)-1987 banned them in Montreal (Montreal Protocol)-After the US banned, but before protocol, the amount of CFC’s emitted leveled off, however after the Montreal Protocol the amount emitted dropped significantly -Aerosols-particles suspended in atmosphere, very small-Deflect radiation back out to spaceLECTURE 3Torricello:-Filled glass tube with mercury (sealed at one end)-Inverted tube in bowl of mercury-Found it didn’t flow out of the tube, height of bottle remained constant-Concluded that ‘pressure’ was holding the mercury at the bottom of the Bowl and not allowing the remaining mercury still in the tube to flow out -Originally recorded results at various altitudes (seeing how much mercury Remained in the tube at different air pressures-Average sea-level conditions caused 29.92 inches to remain -Measured in mb (mini Bar) -Pressure: at a point is the weight of air above that point-Column of air at surface weighs slightly more than 1 Kg per square cm-Pressure = Density X Temperature X Constant(See chart at end of lecture 2 slides of airplane and temperature in atmosphere)-Can see increase in temperature from Tropopause to Stratosphere because that’s where the atmosphere is being heated through the Ozone’s filtering of the sun’s heat-Then, from Stratopause through Mesosphere the temperature drops again; no heating source as pressure -Finally, from Mesopause through Thermosphere the temp rises back up b/c there’s little density and pressure1) Troposphere- where air ‘turns overTemp decreases2) Stratosphere3) Mesosphere- region where temp again decreases with height4) Thermosphere- little mass-High-energy radiation received by thermosphere (high temp experienced)-When atmosphere moves, moves along constant pressure lines (isobars) and not along altitude lines-In meteorology it’s helpful to refer to geopotential height; height of particular pressure value rather than altitude850 mb = 1500 m300 mb = 9000 m TEMPERATURE SCALES-Dr. Fahrenheit was physician, defined upper fixed point, 100 degrees F, as the average temp of his patients-In Centigrade scale, 0 is defined as melting point of ice and upper fixed point 100 is defined as boiling point of water; lowest possible point was -273-Kelvin scale: lower fixed point 0 is theoretically lowest temperature possible, melting point of ice is 273 degrees-Celsius starts at -273, Kelvin starts at 0, but degrees are the same intervalsSPECIFIC HEAT-Specific heat: amount of heat required to increase the temperature of 1 gram of the substance 1 degree C (measured in cal) -Takes less to raise temperature of land, which is why oceans stay more constant HOW IS ENERGY TRANSFERRED IN