Atm Ocn 100 Edition 1nd Lecture 38 Outline of Last Lecture I Reminders II Weather of the day III Mountain Snowstorms IV Orographic Clouds in the Rockies V Water Rights in the West VI Major Issues VII Rocky Mountain Eastern Slope Upslope Storms VIII Cold Air Damming Outline of Current Lecture II Final Exam Review Current Lecture Final Review Session Reminders Homework 7 due today Cloud Project due Sunday Final Exam next Wednesday There is a review session today and Sunday with Stephen Study Guide Final is Wednesday 12 17 at 12 25 in Agr Hall 125 Part 1 10 questions from test 1 Part 2 10 questions from test 2 Part 3 40 questions on subjects covered since last test Tropical Cyclones Extratropical Cyclones Fronts Lake effect storms Mountain snowstorms This study guide is about the last section of the class that we covered Differences between cyclones and anticyclones It really is about the roles in energy transfer Cyclones unlike anticyclones spin in the same sense as the earth The earth is spinning counterclockwise like cyclones in the northern hemisphere In the southern hemisphere the earth would appear to be spinning clockwise and so do the cyclones there Cyclones spin in the same sense as the earth Why is that The reason for this is that air turns it because of coriolis effect But there is something more basic and simple about it Cyclones spin in the same sense as the earth because in every case cyclones represent air rushing toward a point If air is rushing toward a point in all directions it concentrates and gets faster and spins Things moving toward the cyclone are like a skater pulling in his arms and he goes faster On that earth in one particular place the air is rushing toward a place and spinning up Why would it spin the opposite sense for an anticyclone then Because in an anticyclone air is rushing away from a point it is air splatting away If you throw cold air that hits the bottom of the earth it then splats out It is like the skater putting out his arms You will then reduce the spin relative to the earth Because the air splats out it spins less fast An anticyclone splatting out slows down the spin so relative to the earth looking at a weather map relative to the earth it appears to be turning the opposite sense of the earth which is clockwise in the northern hemisphere and counter clockwise in the southern hemisphere The way these are turning is a big hint to the process that created it Things coming together are a cyclone things going apart are anticyclones Differences between extratropical cyclone and tropical cyclone Different roles in energy transfer but for both extratropical and tropical things are rushing toward the middle toward the point of action For tropical cyclone excess heat at the bottom and cold air above and it wants to overturn Air rises from a campfire the flames go up this is because warm air rises Air is always going toward the fire Air is coming from all directions into the fire at the bottom and then it goes up and spreads out Circulation into the fire is like that If that fire was on a turntable or rotating vortex of air the air would spin and the fire would look like a tornado A hurricane is like this too in a hurricane air is rising air is coming in from all sides and rising up Because the earth is spinning air rising up in a hurricane spins in the same sense as the earth Extratropical cyclone air again rushing toward the middle But why Is it because warm air is rising up No The reason the air rushes toward the middle is because air is being drawn to the middle because there is a process of overturning where cold air is next to warm air What happens is that cold air is dense and is heavier per unit volume then the warm air So if there is a barrier keep warm and cold air apart But if you remove barrier cold air drops and sinks underneath And when this happens the cold air would leave a void and a low pressure The low pressure would suck from high pressure where the air is coming together As it sucks the air what happens is as it comes down it will transfer air to the surface and draw warm air into the cold air and pull it over the top The cold air sinks and warm air rises up and come together at low pressure It could form a vortex or a front But even a shear can produce a circulation to begin the pressure will be low at a point and draw air in from all directions and spin up a vortex which is an extratropical cyclone They are not vertical like campfire or tropical cyclone it is slanted It is tilted with height We have terms for this The role of energy transfer that is to bring warm air from below upward In an extratropical cyclone side byside cold air underneath and so on but starts as side by side Baroclinicity Isotherms at angle to isobars on horizontal map It means that you have horizontal difference of warm air and cold air relative to the pressure A system that is this and has a gradient of temperature is cold air side by side with warm air The stronger this is the stronger contrast between warm air and cold air If cold air next to warm air it would be a baroclinic stage because big difference of energy Defines potential energy in a system On the earth you get a lot of this because poles are cold and lower latitudes are warm The baroclinicity is energy available to overturn The problem is that it doesn t do it easily because there has to be barriers overcome to allow it to overturn That involves the rotation of the earth It supports barrier that separates the cold air from the warm air It doesn t easily release the energy but the cyclone does do this Another step to the south every time this happens and then the sun continually heating the earth unevenly builds it back up again Warm air is derived from a warm ocean When earth is 2 3rds water the sun warms the water as opposed to heating the ground The water doesn t get that much warmer in temperature just a little bit 90 of energy goes into heating water Sun shines heats water and then water evaporates into the air and then energy becomes vapor which rises condenses and turns into latent heat which is now in the air and can do something with regards to the rest of the atmospheric circulation which drives baroclinic circulations and so on when it gets higher This transfer mechanism allows from sun to heat atmosphere by evaporating and rising above The tropical cyclone is a small occurrence from energy cycle Tropical cyclone brings air in and transfers energy from the oceans surface It