Introduction to WindNewton’s First Law of MotionAn object at rest will remain at rest and an object in motion will remain in motion (and will travel at a constant velocity along a straight line) as long as no force is exerted on the objectNewton’s Second Law of MotionThe force exerted on an object equals its mass times the acceleration produced (F=ma)Newton’s Third Law of MotionFor every action there is an opposite and equal reactionAtmospheric Forces that Cause Winds to BlowPressure Gradient ForceHigh pressure vs. low pressureAir moves from high to low pressureThe more the pressure difference the more explosive that pressure gradient force isCoriolis ForceDeflection caused by a rotating objectTheoretical force present that causes deflection by contact on a rotating object and that object is the earth rotating on its axisDifference of force between north and southern hemisphereForce is mainly felt in very large scale systemsCF only affects wind directionAmount of deflection depends onRotation of the earthThe latitudeCF is most pronounced at the poles not at the equatorBasically nonexistent at the equator which is why you will never see a hurricane cross the equatorThe object’s speedThe stronger the wind is blowing the greater the CFWind speed affects CF but CF doesn’t affect wind speedHurricane is an example of low pressure and will always rotate counter clockwiseTornados are also low pressure and in the northern hemisphere all tornados will rotate either clockwise or counterclockwise because they are smallerWhen two tornados are rotating next to each other they act as a greater force than the CF so one rotates clockwise and the other rotates counterclockwiseCF deflection in the northern hemisphere is to the right and in the southern hemisphere it is to the leftThis is because high pressure rotates clockwise in southern hemisphere etc.FrictionWind blowing across the earth’s surface and against other air moleculeIn our atmosphere we refer to the first 2000 feet above the ground as being the friction or boundary layerWhen you fly the air tends to be more turbulent closer to the ground because of friction from the earth’s surfaceGeostrophic WindTheoretical horizontal wind blowing in a straight path, parallel to the isobars/constant contour lines, at a constant speedCaused by exact balance of pressure gradient force and the coriolis forceIf you have high and low pressure, the pressure gradient force goes from high to low but then you have to consider the coriolis force and you know deflection is toward the right in the northern hemisphere so it points downThen it all moves clockwise for high pressure and counterclockwise for low pressureFound in upper level wind flowHydrostatic BalanceIn the vertical, an exact balance between vertical pressure gradient force and gravityLets the earth’s atmosphere remain in placeThunderstorms caused the atmosphere to be imbalancedMeasuring and Determining WindCharacterize it by wind direction and wind speed and gustinessSpeed is the amount of air movementWind direction is the direction from which the wind blowsWind gust is a maximum instantaneous readingPrevailing windDominant wind directionWind RosesGraphical device or a chart that has the lengths of the petals that will know how common it is that winds blow from a certain directionWind InstrumentationWind vaneWeight flag that points into the direction the wind is blowingAnemometerHemispheric open cups to catch the wind and the quicker the wind blows that faster the cups spinAerovanePlane spins in the direction the wind is goingWind sockCheapShows the wind directionRawinsondeWind speed and directionballoonDoppler radarAtmospheric profilersDoppler radar that sits on the groundIt looks up and see how the winds are blowing overhead every 6 minutesTo convert from knots to miles/hour you multiply the knots by 1.1510 knots is 11.5 miles/hourScales of Atmospheric MotionMicroscaleThe wind blowing around the side of a buildingSize of the campus or city of AustinMesoscaleSize of a large city to the size of several statesBiggest weather advances over they years have come from this scaleMacroscaleSynoptic (weather map) scaleA picture of the united states as a wholeGlobal scalePictures of the entire disk of the worldSingle Cell Atmospheric Circulation ModelCreated by George HadleyWith higher pressure at the poles, sinking cold air flowed southward from the polar regions… once it got to the equator, after warming, with lower pressure, air was liftedSimply enough… one big circulation cellToo simple!Three Cell Atmospheric Circulation SystemThere is still divergence at the polesEquator has rising air and upper air divergenceIt is really what is in between60 degrees north we have zone where there is some rising motion and we refer to this part of the world as the polar lowif there is rising motion there is surface convergencesubpolar/polar level30 degrees latsubtropical highupper air convergencesinking motionlower air divergenceDeflection in southern hemisphere is to the left and deflection to the northern hemisphere is to the right because of the coriolis forceBetween 30 north and south are the trade wind which is why hurricanes move from east to west when they first start outArea around the equatorDoldrumsCalled this because when you get close to sea level and it is hazy and foggy then sun gets higher then clouds come together then it starts to rain then it starts to clear and then the next day the cycle happens againThis happens everyday in the tropicsThere is very little change in the climateInner tropical convergence zoneThat long term says exactly what is meansIt is found in an inner tropical area of convergenceFurther to the NorthYou don’t have much wind up high and if you are planning on traveling with a big sail and hoping for wind you aren’t lucky because in the middle of the ocean there isn’t a lot of windGiven the name the Horse Latitudes because in the older days they would throw animals off the boat to try to keep going west to lighten the load of the boat even though it didn’t help them get anywhereIf you want to go west you do it further southIf you want to come east you do it further northAverage Global Surface PressureJanuaryHighs are over landLow pressure is over the waterDuring the respective season your in in the northern hemisphere you will find high pressure favoring the wind in the winter because its colderJulyHigh pressure is over waterLow pressure is over the