Lecture 10Outline of Last Lecture I. Weather MapsII. Constant Height MapsIII. Constant Pressure SurfaceIV. Constant Pressure Surface- Heating and CoolingV. Analogy: Topographic MapsVI. Constant Pressure MapsVII. Forces in the AtmosphereVIII. Review of PressureIX. Pressure GradientX. Pressure Gradient ForceXI. Rotation of the Earth: Coriolis ForceXII. Merry-Go-Round ExampleXIII. The Coriolis ForceXIV. Coriolis Force and LatitudeXV.Coriolis ForceOutline of Current Lecture XVI. Upper-Level Winds ReviewXVII. The Geostroph WindXVIII. The Geostrophic WindXIX. Analyzing Upper-Air MapsXX.Circular MotionXXI. Curved Flow Around LowsATMS 100 1st EditionXXII. Curved Flow Around HighsXXIII. Curved Flow Aloft: Gradient Wind BalanceXXIV. Upper-Level MapsXXV. NomenclatureXXVI. Surface WindsCurrent LectureXXVII. Upper-Level Winds Reviewa. Pressure Gradient Force (PGF) acts perpendicular to the height lines toward low heights (or low pressure)i. magnitude of PGF deteremined by spacing of height lines (or isobars)b. Coriolis force always acts to right of motion in the Northern Hemi-spherei. maginitude of Coriolis force proportional to wind speedc. Friction not important at upper levelsXXVIII. The Geostroph WindThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is besta. Point 1: Air parcel initially motonless. Flip switch to “turn on” laws of physics. Parcel begins to accelerate toward lower pressure owing to PGFb. Point 2: As air parcel accelerates, it begins to be deflected to its right by the Coriolis force.c. Points 3 and 4: As air parcel continues to speed up, Coriolis force grows in magnitude. PGF is constant (determined by spacing between isobars)d. Point 5: Eventually air parcel deflected enough so it is moving parallel to height contours. At this point, PGF and Coriolis forces will be equal and opposite.e. Wind is called geostrophic windi. parallel to height contours (isobars)XXIX. The Geostrohpic Winda. Winds aloft blow parallel to height contours b. PGF balances Coriolis forcei. force same magnitude, but in opposite directionsii. net force (acceleration) on air is zeroiii. assumes straight isobarsc. Stronger PGF= Faster Windsd. Tighter Contour lines= faster windse. How to determine wind direction:i. if the wind hits you in the back, low heights (low pressures) are on your left1. upper level flow only2. Northern Hemisphere onlyXXX. ***Analyzing Upper-Air Maps***e. PGF: perpendicular to height lines/low heightsf. Wind: low heights/low pressure on your leftg. CF: perpendicular/right of the windh. Geostrophic Wind is valid for straight flow aloft:i. first, determine areas of high heights and areas of low heightsii. at each point, PGF acts perpendicular to the height lines, to-ward low heightsiii. Geostrophics win blows parallel to height lines such that if the wind hits you in back, low heights are on your leftiv. Coriolois force acts perpendicular and to right of wind direction (should point in opposite direction of PGF)XXXI. Circular Motione. Newton’s Second Law:i. force=mass x accelerationf. acceleration is any change in speed or directiong. for circular motion, object is constantly chaning direction (acceleration),even if speed is constanth. net force required to maintain circular motion called centripetal forcei. directed inward toward center of circlei. for curved flow, PGF and Coriolis forces cannot balance (add to zero)i. balanced forces = no accelerationii. one force must be greater than the other because there must be a net inward force to change directionXXXII. Curved Flow Around Lowse. PGF directed inward toward center of low f. Coriolis Force directed to right of winds; outwardg. For curved flow, must have net force directed inward toward center of lowi. centripetal forceii. keeps flow in circleh. PGF; must be greater than coriolis force around lowsXXXIII. Curved Flow Around Highs Alofte. PGF directed outward from the center of the highf. Coriolois force directed to right of winds; inwardg. For curved flow must have net force directed inward toward center highi. centripetal forceii. keeps flow in circleh. Coriolois Force must be greater than PGF around highsXXXIV. Curved Flow Aloft: Gradient Wind Balancee. called gradient wind balance (althought PGF and CF are not bal-anced)i. Lows: PFG greater than CFii. Highs: CF greater than PGFiii. must have these force imbalances or flow would not go in a cir-cleiv. need net force inward toward center of circlef. recall that PGF determined by height gradientg. CF determined by wind speedh. given PGF- wind speed will be faster around highs and slower around lowsXXXV. Upper-Level Mapse. winds blow parallel to contour linesi. lines typically wavy (west to east)ii. zonal flow- westeral flowiii. meridional flow- northerly/southerly flowf. warmer air (high heights) typically found in tropicsg. colder air (low heights) typically found near polesXXXVI. Nonmenclaturee. Cyclones: low pressure systemi. NH: flow counter-clockwiseii. SH: flow clockwise1. Cyclonic flowf. Anti-Cyclone: high pressure systemsi. NH: flow clockwiseii. SH: flow counter-clockwiseiii. Antcyclonic flowXXXVII. Surface Windse. Generally slower than upper-level windsf. Cross isobars at an anglei. wind does not flow paraellel to isobars lke upper-level windsii. WHY?1. friction2. friction opposes motion, slowing the winds, and weaking the CFiii. intially, assume winds in geostrophic balanceiv. add friction:1. slow winds2. weaken CFv. net force in direction of PGFvi. winds deflected in direction of PGF1. toward low pressurevii. CF always perpendicular and to right of windviii. Result in 3 way balance between PGF, CF, and Frictional Forcesix. Northern Hemisphere1. Lows: winds sprial inward, counter-clockwise2. Highs: winds spiral outward; clockwise rotationx. Southern Hemisphere1. Lows: winds spiral inward; clock wise rotation2. Highs: winds spiral outward; counter-clockwisexi. surfce winds ALWAYS cross isobars at an angle from highto low pressure1. SURFACE WINDS DO NOT BLOW PARALLEL TO