Final Exam Review AOSC200 Final Exam Review Lecture 27 May 13 2014 05 13 2014 What has this whole class been about in one word The sun solar energy Weather is day to day changes Climate is the long term changes Cold Fronts Warm Front Represented as blue triangles pointing toward warm air Travels 35KPH Warm air force up cools releases latent heat leads to storms Represented as red semi circles pointing toward cold air Travels 25KPH Warm air slide up cold air slowly cold Cloud form starting with cirrus then various layers of stratus Occluded Fronts Warm type occlusion and cold type occlusion Represented as purple semi circles and triangles Cold front moves faster than warm front may catch warm front Warm air is force up over both cold cool air masses May have mix of clouds similar to both cold and warm fronts Cyclogenesis in 3 D occluded fronts extra tropical cyclone 500 mb area of convergence sends upper air to surface Surface low sends warm surface air aloft Leads to Baroclinic instability High pressure convergence Low pressure divergence Dry Line Cold dry air and warm moist air meet Hot dry air at point of convergence Forms dry line Sever storms often form at this point Cloud Formation Orographic Lifting o Air is forced up the side of a mountain and cools as it rises o A cold front will lift warm air that it comes in contact with o As surface air is warmed by the sun it becomes less dense Frontal Lifting Convection and rises Convergence o When wind meets from different directions the air in between has no place to go but up Dry Adiabatic Lapse Rate Lapse Rate the rate at which temperature changes with height Adiabatic no heat energy is gained or lost by the air parcel 10 degrees km Saturated Adiabatic Lapse Rate 6 degrees km once water begins to condense latent heat is released air parcel cools at a slower rate than if air parcel was dry Clouds precipitation Single Cell Air mass thunderstorm look at notes and lecture approximately 30 minutes into video Cumulus stage Needs source of warm moist air Water condenses and cloud spreads out in all directions Dry air entrained in from all sides o Leads to different sized droplets which promotes growth of droplets Precipitation begins to form Process takes approximately an hour Multi cell Thunderstorms Wind shear keeps the downdraft from interfering with the updraft Strong down draft aids the updraft gust front NEEDS WIND SHEAR Increased updraft aids in the formation of new cells o Strong upper level winds separate updraft from downdraft o Downdraft causes more warm air to rise and strengthens the storm Squall Lines o Line of intense individual storms o May last 6 12 hours o Occur along boundary of unstable air o Strong wind shear tilts updraft and separates it from downdraft Mesoscale Convective Complex o Composed of multiple single cell storm in different stages of o Individual thunderstorms supports formation of other development convective cells o To last a long time need a good supply of moist air near surface o Rear flank downdraft Strengthens storm Strengthens tornado spins up tornado updraft Also leads to death of tornado b c cuts of updraft energy supply of energy Tornado Life cycle Organizing stage Mature stage Shrinking stage Rope stage Lightning Ground sends out positive streamers that wait for the stepped leaders to make contact Once contact is made an ionized channel is created between cloud Positive charges rush up through the channel making the return and ground stroke o Brightest par of the lightning Process can happen several times very rapidly Conceptual Model Warmest air in tropics hottest ocean temperatures Air rises until hits tropopause and spreads out Coriolis forces take over and curve to right left o Depends on hemisphere As it moves north or south it cools and sinks Watch lecture to get rest of description Sea level pressure in summer Low pressure systems form over land in NH summer o Thermal lows ITCZ has moved northward Similar pattern develops in SH summer Rossby Waves Zonal flow around much Meridional Flow to east Split Flow o Jet stream moves from west to east without meandering o Jet stream wanders around a lot as the wind moves from west o Zonal flow near the pole o meridional flow to the south Poleward transport of energy How is energy balanced between tropics and extra tropics o Rossby waves and ocean transport Tropical Cyclone Life Cycle Tropical Disturbance o Tropical weather system 10 300 nmi in diameter o Originates in tropics or subtropics o May be associated with perturbations in the wind field known as easterly waves Tropical Depression o Strengthens o Counter clockwise spin Tropical Storm o Gets a name Hurricane o Winds 74 mph or greater o Catergory determined by Saffir Simpson scale o Clearly defined eye relatively calm o Eye wall winds strongest o Central pressure drops very low o Recurvature and Bermuda High Damage Wind o Hurricane winds can be increased or reduced alone path o Can spin off tornadoes o Strongest winds always to right of direction of motion Typically northeast of storm Sea water storm surge o Ocean water piles up in front of storm due to winds and low pressure Rain fall Ocean Currents Gyre ocean circulation that forms closed loop and stretches across entire ocean basin Ekman Spiral and Ekman transport o Upper level winds pull ocean with it o Coriolis forces take over and pull it to right Top lay of water o Top layer wants to move second layer of water Coriolis forces take over and pull it to right o As you go down further and further the direction of the water changes o If you take overall average direction average is towards Coriolis force Ekman Transport perpendicular to original direction OFFSHORE Leads to upwelling Forces Gravity Pressure Gradient Centrifugal Coriolis Friction Force Balance Hydrostatic Geostrophic Gradient Guldberg Mohn Thermal Wind Types of Forecasts Folklore o Based on traditional proverbs sometimes accurate o Uses animal behavior and other creatures as predictoes o assumes that the weather will not exhibit large day to day o The weather tomorrow will be like the weather today o we know these will be wrong because eventually the weather Persistence fluctuations WILL change climatology o assumes the weather for a day or a season will be close to the average weather for that day or season o we know these will be wrong because eventually the weather WILL deviate from the average o Recognizes that weather causing patterns move but assumes the following