Geology 1350 Lecture 14 Outline of Last Lecture I. ScalesII. Types of windsOutline of Current Lecture I. Global windsCurrent LectureAtmospheric general circulation (global)- avg wind patterns Underlying cause of this- why have high and low temps? Unequal heating Sun is the driving force, uneven solar radiation , equator heats up more because higher solar radiation (causes Hadley cells- extends to subtropics ) which redistributes rising heat from equator low to polar highs Single cell-radiation- static(no rotation) describes general wind pattern Three cell circulation model- (mtns continents and ice fields alter this)since earth rotates this breaks the single cell (Hadley cell),( ferrel cell- extends over the latitudes), (polar cell- extends over the poles)The Coriolis force creates westerlies (beteween 30 and 60 degrees)and NE trade winds(occupymost of tropics)(easterly winds dominate from equator 30 degrees)(intertropical convergence zone is the boundary b/n NE and SE), and the polar(60 degrees) front redistributes cold air, weak winds near equator Doldrums- regions near equator characterized as weak winds, strong rising motion, towering convective clouds and thunderstormsSubtropical highs- high pressure at 30 degrees (horse lat) caused by cooling of equatorial air as it moves northward and convergence (pile up) of air above. Sinking motion, clear sky, major deserts, warm surface temp.Polar front- seperates tropical from polar air massesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Subpolar low- low pressure zone near polar frontPolar easterlies- shallow layer of northeasterly flows forms when the southward moving cold polar air behind the polar front is deflected by the Coriolis force to the right of its pathGlobal precipitation patterns- global low pressure zones around the equator and 60 degrees lat. Generate convergence at the surface, rising air and cloud formation, zones of high pressure at 30 degrees and the poles experience convergence above with sinking drying airSemi-permanent high and low pressure systems persist throughout large periods of the year, winter, highs form over land-lows over ocean and vice versa during summer; Bermuda high and pacific high form near 30 degrees north, in response to air convergence aboveWinds in January- Observed average global pressure and winds have increased complexity due to continents and the tilted earth. Differential ocean-land heating creates areas of semi-permanent high and low pressure that guide winds and redistribute heat.Winds in June- global pressure and wind dynamics shift as the Northern Hemisphere tilts toward the sun, bringing the intertropical convergence zone, the Pacific high, and blocking highs in the southern oceans northward.4 semi permanent pressure systems- Bermuda and pacific high (horse lat 30 deg.), Icelandic and Aleutian low (b/n 40-65 deg), other high and lows aren’t perm. Ex. Siberian high becomeslow in july(intense) responsible for indian monsoons, Canadian high becomes low in july (less intense) mexico monsoonsCoastal summer weather- The semi-permanent Pacific high blocks moist maritime winds and rain from theCalifornia coast, while the Bermuda high pushes moist tropical air and humidity overthe eastern states.Winds aloft in January-Land-sea temperature differences trigger ridges and troughs in the isobaric surface. Horizontal temperature gradients establish pressure gradients that cause westerly winds in the mid latitudes.Winds aloft in june-Usually strongest during winter times in each hemisphere. Same pressure gradient aloft will cause stronger winds compared with same pressure gradient on surface due to less air density aloft.Jet stream-high velocity, polar and subtropical jet stream winds are in lower tropopause, along ridges and troughs,Polar jet formation- steep gradients of temp. change at the polar front trigger steep pressure gradients and forces higher velocity geostrophic winds300mb winds and jets- jet streaks are the maximum winds exceeding 100 knotsPolar jet is typically found over central Canada in summer and in winter it is positioned over the northern and central US.Surface ocean currents-surface winds cause ocean water drift, piling up, and creation of pressure differences that generates ocean circulation, major ocean currents are known as warm or cold and help redistribute heat, Coriolis force deflects currentsCold water upwelling- maps of west coast sea surface temp. indicate regions of significantly cooler water that has welled from below.Eckman spiral and upwelling- Coriolis force directs surface water to the right of the southwardblowing winds along californias coast , it removes water from the coast and then replaced by upwelling of deeper waterEl nino- ocean surface warming (coast of peru and Ecuador), increase temp causes pressure, wind and precipitation in tropical pacific that impacts regions far from the tropical pacific, varies in strengths with sea-surface temp. changes from 1-2F to more than 10FNormal conditions- high pressure over the southeastern pacific and lower pressure near Indonesia, easterly trade winds along the equator, rising air and heavy rain over western Pacific and sinking motion and generally dry weather over eastern PacificEl nino condition- pressure increases over the western Pacific and falls over the eastern Pacificchanges in pressure causes trade winds to weaken or even reverse in direction rising, rain over western Pacific and sinking and dry over eastern PacificEl nino-warmer than normal temp. over the eastern tropical pacific (wetter and cooler over California and southern US, warmer and dryer over large part of north America)La nina- (colder in western US, wetter over pacific northwest, warmer and dryer in southern US) colder than normal surface water moves over central and eastern pacificEnso index- El Nino Southern Oscillation (ENSO) intensity has been tracked using 6 parameters, including air and sea temperature, sea level pressure, wind speed and direction, and cloudiness.A graph of the ENSO index shows eastern Pacific warm El Niño and cool La Niña years.Global el nino impacts- The El Niño Southern Oscillation (ENSO) is part of a planetary ocean-atmosphere interaction, and can take several years to run its course. ENSO causes abnormalities around the