You are watching: Hurricanes form in tropical waters between the latitudes of
|both species of storms havelow press centers (the ax cyclone refers to winds blowing about low pressure)|
|upper level aberration iswhat causes both species of storms come intensify(intensification method the surface low press gets also lower)|
|1. Middle latitude stormsare bigger, probably 1000 mile in diameter (half the US)||1. Hurricanes space smaller, 100s of mile in diameter (fill the Gulf the Mexico)|
|2. Development can occur overland or water||2. Have the right to only type over warmocean waterweaken rapidly as soon as they move over soil or cold water|
|3. Type at center (30oto 60o) latitudes||3. Form in the sub tropics,5oto 20o latitude|
|4. Prevailing westerliesmove this storms native west to eastern||4. Profession winds movehurricanes from eastern to west|
|5. Storm season: winter toearly feather||5. Storm season: latesummerto fall (when s water is warmest)|
|6. Air masses that differenttemperatures collide follow me fronts||6. Single warm moist airmass|
|7. All types ofprecipitation: rain, snow, sleet freezing rain||7. Mostly just lots (a footor more) the rain|
|8. Just an occasional stormgets a surname ("The Perfect Storm", "Storm the the Century", etc.)||8. Dry storms &hurricanes it s okay names|
The figure above showsthe family member frequency oftropical cyclonedevelopment in various parts that the world.The name hurricane, cyclone, and also typhoon all describe the same type ofstorm (tropical cyclone is a generic name that have the right to be usedanywhere). In many years the s off the shore of SE Asia istheworld"s most active hurricane zone. Hurricanes arevery rarely offthe eastand west coastlines of southern America.Hurricanes form between 5 and 20 levels latitude,over warmth oceanwater, north and south the the equator. The warmlayer of watermust be reasonably deep come contain enough energy to fuel a hurricane and sothat turbulence and also mixing don"t lug cold water up to the oceansurface. The ptcouncil.netsphere should be stormy so the thunderstormscan develop. Hurricanes will only type when over there is really littleor no upright wind shear (changing wind direction or rate withaltitude). Hurricanes don"t form at the equator since there isno Coriolis force there (the Coriolis pressure is what gives hurricanestheir spin and also it reasons hurricanes to spin in opposite direction inthe northern and also southern hemispheres).Note that more tropicalcyclones type off thewest shore of the us thanoff the eastern coast. The west coast hurricanes don"t normally getmuch attention, due to the fact that they move away from the coast and also usuallydon"tpresent a danger to the united state (except sometimes to the state ofHawaii). The humidity from this storms willsometimes be traction up right into the southwestern united state where it deserve to lead toheavy rain and flooding.
Hurricane season in the Atlanticofficially runs fromJune 1 through to November 30. The height of hurricane season is inSeptember. In 2005, an unusually energetic hurricane season in theAtlantic, hurricanes continued through December and even right into January2006. Hurricane season in the Pacific starts two weeks earlier onMay 15 andruns v Nov. 30.Some kindof meteorological process that produce lowlevelconvergenceis required to initiate a hurricane. One possibility, and the onethat fuels many of the strong N. Atlantic hurricanes, is one "easterlywave." This is just a "wiggle" in the wind flow pattern.Here"s a little bit better sketch than the one ~ above p. 142 in thephotocopied ClassNotes.
In some means winds blowing throughan easterly wave resemblestrafficon a multi-lane highway. Traffic will sluggish down and start tobunch up as it philosophies an obstruction. This is like theconvergence the occurs when air flows right into an easterly wave.Once through the"bottleneck" website traffic will begin to flow much more freely.Easterly waves often form over Africa or just off the African shore andthen travel toward the west throughout the N. Atlantic. Windsconverge together they approach the wave and also then diverge oncethey arepast the . The convergence will reason air to climb andthunderstormsto begin to develop.
|Normal hurricane activityin the Pacific||Normal hurricane activityin the Atlantic|
|16tropical storms per year8 reach hurricane strength0 fight the united state coastline||10tropical storms per year6 with hurricane strength2 fight the united state coastline|
In an mean year, in the N.Atlantic, there will be 10 namedstorms(tropical storms or hurricanes) that develop during hurricaneseason. 2005 was, if friend remember, a really unusualyear. Therewere 28 named storms in the N. Atlantic in 2005. The beat theprevious record of 21 names storms that had been set in 1933. Ofthe 28 named storms, 15 developed into hurricanes.This is a reasonablyimportant figure. It tries to define how acluster the thunderstorms deserve to organize and intensify into a hurricane.
1. Converging surface windspickup heat and moisture from the ocean. These are the two mainssources of power for the hurricane.2. Climbing air expands, cools, and also thunderstorm cloudsform. Therelease of implicitly heat throughout condensation warms the ptcouncil.netsphere.The main point of a hurricane is warmer 보다 the air approximately it.3. Pressure decreases an ext slowly through increasingaltitudein the warm core the the hurricane. The result is that push atthe top facility of the hurricane is greater than the push at the topedges of the hurricane (pressure at the top facility is still reduced thanthepressure in ~ the bottom center of the hurricane). Top levelswinds diverge and spiral outwardfrom the top center of the hurricane (you deserve to sometimes check out this onsatellite photographs of hurricanes).4. The top level aberration will cause the surfacepressure at the center of the hurricane to decrease. The speed ofthe converging surface winds increasesand the storm intensifies. The converging winds choose upadditional heat and also moisture i beg your pardon warms the main point of the hurricane evenmore. The top level high pressure and the upper leveldivergence increase. The increased aberration lowers the surfacepressure even more.
In the figureat left the moderate divergence discovered at top levels is stronger thantheweak surface convergence. Divergence is removing much more air 보다 isbeing included by surface ar convergence. The surface ar low push willdecrease. The to decrease in surface push will reason theconverging surface ar winds to blow faster.In the center picture, the surface ar low push is lower, thesurfaceconvergence has actually strengthened to moderate levels. The upper leveldivergence has also strengthened. The upper level divergence isstillstronger than the surface ar convergence therefore the surface ar lowpressure willdecrease even an ext and the storm will intensify.In the right figure the surface ar low pressure has reduced enoughthatthe solid surface convergence currently balances the solid upper leveldivergence.The storm won"t strengthen any kind of more.Generally speak the reduced the surface push at the center ofahurricane the more powerful the storm and the faster the surface winds willblow.
This number tries to present therelationship in between surfacepressure and surface wind speed. The human being record lowsea level pressure reading, 870 mb, to be setby Typooon pointer off the SE Asia coastline in 1979. Sustained winds inthat storm to be 190MPH. Three 2005 Atlantic hurricanes: Wilma, Rita, and Katrina hadpressures in the 880 mb to 900 mb range and winds varying from 170 to190 MPH.
A tropical disturbance is just alocalized swarm of thunderstormsthat a meterologist can see on a satellite photograph. However thiswould merit observation since of the potential for furtherdevelopment. Indications of rotation would be evidence of organizationand the arising storm would be dubbed a tropic depression.In order come be called a tropic storm the storm muststrenthen a littlemore, and winds mustincrease to 35 knots. The storm receive a name at thispoint. Finally when winds exceed 75 MPH (easier come remember than65 knots or 74 MPH) the storm i do not care a hurricane. Friend don"t needto remember all these names, just try to remember the informationhighlighted above.
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A crossectional see of a maturehurricane (top) and also apicturelike you mightsee on a satellite photograph (below). Sinking waiting in the an extremely center that a hurricane produce the clearskiesof the eye, a hurricane"s many distinctive feature. The eye istypically a couple of 10s of mile across, despite it might only it is in a few milesacross in the the strongest hurricanes. Generally speaking thesmaller the eye, the stronger the storm.A ring of strong thunderstorms, the eye wall, surrounds theeye.This is wherein the hurricane"s the strongest winds space found. Extr concentric rings of thunderstorms are uncovered as you moveoutward native the facility of the hurricane. These are dubbed rainbands. These typically aren"t visible until you acquire to the outeredge the the hurricane due to the fact that they space covered by high altitude layerclouds.