and basically what we learned in chapter six is that air is constantly moving air tries to balance out so air flows from higher pressure to lower pressure so with air flowing the higher pressure of low pressure the winds start to curve into low pressure in a counterclockwise fashion convergence at the surface you remember back in chapter 4 where we talked about convection when you heat the atmosphere air will rise and what happens is as air rises you get convergence at the surface so where do you find the most heat on the earth well when we talked about chapter two the heating of the earth there's a surplus around the equator so the equator gets very very hot and that's where you start to see low pressure starting to rise so around the globe you're going to have different circulations and that's one of the things that we're going to be looking at as we go through chapter 7. what's the wind flow in the united states what's the wind flow near the north pole what's the wind flow near the equator what's the wind flow near florida or what we say 30 degrees north what's the wind flow at 90 degrees north what's the wind flow at 60 degrees north so we want to understand the wind flow around the globe so chapter 7 is about circulation of the atmosphere right here circulation of the atmosphere and overall there's different scales to this weather patterns so when we look at the global scale we're talking about major storm systems circumventing the globe that will move from asia around into the pacific ocean into the united states back out to the atlantic ocean into europe and so forth and so on finger around the globe and part of that scale or planetary scale okay those are long waves in the westerlies so we're talking about constant moving of air over several thousand miles constant moving around the globe so our scales of motion that we're going to be looking at they're categorized by their size and their lifespan are they constantly moving that they're around for weeks and months and years or are they around for a short period of time that they're here for maybe 10 seconds or they're here for an hour and then they're gone so there's different scales and different time frames that we're going to be looking at as far as the air moves so remember chapter 6 air pressure and winds how is the air moving so we're looking at low pressures and high pressures winds move in a certain direction thanks to those three forces remember the pressure gradient force cordless force and friction those three forces change the wind at the surface all right so let's talk about these scales of motion one is macro scale or planetary scale those are long waves in the westerly they last for a long time then we have some noctux scale which is a weather map think about the united states we're talking about two three four thousand miles and this is going to include cyclones and anti-cyclones or as you now know high pressure and low pressure then we're going to be looking at mesoscale metal scales much smaller we're looking at thunderstorms tornadoes land and sea breezes now we're talking talking over a much shorter geographic distance and we're also looking at a much shorter time frame so for example a thunderstorm most thunderstorms last an hour two hours maybe four hours tops and they cover maybe 10 miles 100 miles 300 miles so a much smaller scale moving with thunderstorms same thing with tornadoes and think of the sea breeze on long island winds coming off the atlantic ocean it cools down the south shore and an air starts to rise so these are much smaller scales compared to our planetary scale and synoptic scale then we have micro scale micro scale is our smallest scale and that small scale covers a very small geographic location or distance and also a time frame so one example would be a wind gust remember if you're walking outside all sudden the wind picks up that doesn't stay that way for hours and hours and hours a wind gust a little bit of turbulence would last maybe 15 minutes 20 minutes 30 minutes maybe you're walking across farmandale state college around campus you see the trees move very briefly and then it's over so those are micro scale very small time frame very small geographic location mesoscale by the way mesocyclone that is also an indication of a very intense rotation it's an indication of a possible tornado so mesoscale thunderstorms tornadoes land and sea breezes mesocyclone could be the formation of a tornado so those are the scales of motion that we're going to be looking at so this is the diagram from our book and you can see on the left hand side it talks about the life span and on the bottom it talks about what the actual scale is so again micro scale a wind gust a microburst or a dust devil a dust devil is a very quick um movement of air that kind of pulls up the dirt along the ground and kind of moves things around very different from a tornado where a tornado will pull air up but at a much stronger strength so days to weeks hours days minutes hours seconds to minutes that is our lifespan our scale micro scale meso scale then we get into synoptic scale and planetary scale and you'll see macro scale goes up to more than 40 to 50 000 miles so you can see thunderstorms and tornado that's on that meso scale minutes to hours wind gusts micro scale micro burst that can come out of a thunderstorm so very small very intense and only around for a very short period of time hurricanes anti-cyclones so high pressures and low pressures they can be around days to week that would be under our synoptic scale and then long waves into wesley trade winds we're going to talk about the trade winds in just a moment so these are much longer scales meaning that they're going to cover a much longer geographic distance and also they're going to be around for a much longer time as you can see days to week so westerlies in the atmosphere they constantly move around the entire globe covering 30 40 to 50 000 miles so this is our lifespan verso scale this is the exact diagram from your book in chapter seven so you can get an idea of those scales now we're constantly looking at air moving and air can constantly move all over the place up and down that's what chapter four was talking about how do we get air to go up and down and a difference in pressure will cause wind that's what we learned in chapter six so when you have a difference in pressure higher pressure and lower pressure you can get these different types of mesoscale or micro scale winds and here's an example of a valley breeze where you have the cool air sinking and then warm air rising along the mountains and at night you would have the opposite where you get the warm air rising in the center of the mountain range here this is the valley and then the cold air kind of sinks off the mountain so this is just one example that we could look at the smaller scale of our winds so as we take a look going back at our wind scales and what happens and the sea breeze is also a part of that mesoscale where you get winds coming in off the water you have a difference in pressure out over the ocean you have high pressure converging air and this is convergence right here the land heats up very fast you get convection air rises and with that the air wants to fill a void so that's why you get the wind off the water coming in over land this is the sea breeze air is stable out over the ocean land air masses heat up very rapidly you get convection air rises and you get convergence where the wind flows from higher pressure out of the water to lower pressure over land and you can kind of see this cycle on this diagram where the wind flows from the ocean out over land rises and if you have enough convection you get clouds and if you remember if you've ever visited to florida you get a lot of heating during the afternoon and a lot of afternoon thunderstorms that's a stronger sea breeze compared to long island a lot of times long island we just get the clouds building and most of the time you'll see them developing right along the lie that's where the convection of the center island would be that's where we get the rising air so sea breeze is on that mesoscale time slot and this can be around four minutes to hours and you get the cooler air coming in off the ocean so jones beach robert moses the south shore could have temperatures in the 70s but places near the l.i.e dix hills plainview cyacid could be in the 80s to around 90 degrees so that is our sea breeze where the air flows from the ocean into the land as the air is heated up faster over the land you get converging air from the ocean all right so in chapter 7 we're constantly watching air moving circulation of the atmosphere you can see the different diagrams here of that sea breeze so one of the things i want to look at is the global perspective what's happening around the globe this is a one of the diagrams and also as you take a look at in your study by chapter you will also see this as well so this is from your pearson so if you're going in chapter seven you can look into the smart figures of global circulation you can look at the e-text and this is that same diagram and you can play this diagram and kind of see where the air is moving and how the air is moving as well and you can see right here on this diagram that there's different names around the globe and that's one of the things that we're going to be looking at each wind flow has a different name and we can get an idea what the weather may be because of that wind flow in different portions of the globe all right so let me get rid of some of these maps here so going back to our global circulation if you look at pages 195 to about 202 you're going to see all these different diagrams in the book and also you can look at the e-text through uh the pearson study guide as well so one of the things i want you to notice is that notice along the equator we have these red hours that's warm air moving in so at the equator we get a lot of incoming solar radiation remember chapter two a lot of incoming solar creation so as the air is heated at the ground very rapidly it becomes very buoyant so that air rises at the equator so now you have convergence so converging air into the equator warm air moving into the equator and that air is rising so this is part of what we call the hadley cell a scientist many years ago figured out hey air flows from high pressure to low pressure where is low pressure where is high pressure and this cell only dealt with right around 30 degrees north to the equator so you can see the red arrows indicate warm air the blue arrows represent colder air so you have warm air rising at the equator and remember from chapter six converging air at the surface diverging air aloft so this is where we have low pressure at the equator so converging air at the surface diverging air aloft so as that air is diverging outward it's going to be sinking okay and converging into higher pressure and then going down to the ground and spreading out again so we have low pressure at the equator and we have higher pressure okay at 30 degrees north this is what we would call our subtropical high so at 30 degrees north we have diverging air at the surface it is converging into the equator so along the equator we have several different uh signifiers for low pressure one area this is called the equatorial low at the equator you have locus band here and near the equator we have what we call the inter-tropical convergence zone inter-tropical convergence zone inter-tropical convergence remember convergence air is coming together near the equator now this air mass will fluctuate throughout the year thanks to remember from chapter two where the sun's directs are rays are hitting so during our summer this equatorial low inter tropical convergence zone the doldrums moves a little further north during our summer it gets closer to around 10 degrees north and then it goes a little bit further south during our winter so it this will move with fluctuation during the seasons where's the warmest air the sun's direct race hitting and then where it moves throughout the year so at the equator you have the equatorial low doldrums and the intertropical convergence zone now you have converging air from high pressure at 30 degrees north this is called the northeast trade winds here's your trade winds wind flowing out of high pressure into low pressure out of high pressure into low pressure so the northeast trade winds okay are the winds coming out of high pressure converging into this low pressure and the reason why it's called the northeast winds because the winds are coming from the northeast remember wind flow around high pressure is clockwise so when you have high pressure at 30 degrees north it's clockwise you get one degree one direction in the united states and a different direction as you get near the equator so from 30 degrees north to the equator that is the northeast winds and the wind is flowing out of high pressure into low pressure 30 degrees north again which is called the subtropical high clockwise wind flow in the united states see these red arrows that is called the westerlies the winds blowing in the united states from the west to the east from the west to the east the united states so our storm systems come from the pacific ocean generally into california oregon and washington and move eastward now they don't always move in a direct line but the general track as they're flowing is moving west to east in the united states so from 30 degrees north to 60 degrees north that is what we call the wind flow the westerly so this map is showing circulation or wind flow around the entire globe so let's do a little bit of a recap the equatorial doldrums or the intertropical convergence zone is formed from the converging air where the northeast trade winds meet south of the equator these are the southeast trade winds high pressure down around 30 degrees south high pressure flows counterclockwise there's a different wind flow south of the equator so you have the southeast trade winds meeting the northeast trade winds that is the inter-tropical convergence zone that's where the equatorial low is that is also where the doldrums is at 30 degrees north we have the subtropical high high pressure wind flowing clockwise here now also at the north pole you have very cold air that's where high pressure is so you have high pressure at the north pole high pressure at 30 degrees north and at 60 degrees north we have low pressure so take a look at this globally now at 90 degrees north or the north pole wind is flowing out with cold dense air is sinking down to the ground and spreading out so at 90 degrees north we have the polar high at 60 degrees north we have the polar front we have converging air these polar easterlies are the wind flow coming out of high pressure so out of the high pressure out of the north pole you have the polar easterlies the high pressure near the subtropical high you have the northeast trade winds and then to the north of that you have the westerlies so where the polar easterlies are meeting the polar westerlies we get the subpolar low and the polar front so along 60 degrees north we get the polar low okay with a polar front and the subpolar low converging air at around 60 degrees north converging air at the equator diverging air this is all off the surface diverging air at the north pole and 30 degrees north and 30 degrees south so notice the blue arrows that's cold air the red arrows warm air so you have air constantly rising converging and diverging so let's look at this again at the north pole you have the polar high wind flows outward at the surface you get polar easterlies at the surface you get air converging at 60 degrees north which is the subpolar low or the polar front in the united states from 30 degrees north to 60 degrees north you are looking at the westerlies along 30 degrees north we have what we call the subtropical high from 30 degrees north to the equator you have the northeast trade winds at the equator you have the equatorial low doldrums and also the tropical convergence zones and down near 30 degrees south you also have the subtropical high but from 30 degrees south towards the equator you have a wind flow called the southeast trade winds so you have a lot of different winds and global circulation remember wind flows from high pressure to low pressure high pressure to low pressure so the other thing here is see along 30 degrees north you have something called the horse latitudes well way back when the 1400 1300s 1500s when um you had sailors coming in from portugal and spain from europe trying to come into the united states well right along 30 degrees north you have high pressure high pressure tends to have lighter winds than lower pressure so when you had sailboats coming in from portugal and spain and europe as they were going through high pressure there wasn't much wind to fill the sails to move the boats so they had to make the ships lighter they had men who rode the boats okay and they had the sails but if you didn't have support of the wind moving the sails it was very difficult also to row the boat so to get a sailboat to move you need to make it lighter and one of the things they did was they threw the horses overboard horses weigh a lot okay they could weigh two three four five hundred pounds they either ate them or they threw them overboard so their boats could move to get to the new world or what we now know the united states or the caribbean so that's why around 30 degrees north where we have high pressure you generally have light winds that's why this is called the horse latitudes is because when the sailors from europe came over to what is now known as the united states in the caribbean they didn't have much wind they had to make their boats lighter they threw the horses overboard i know it sounds kind of weird but 30 degrees north where the subtropical high is that's also typically where you have the lighter winds so generally where you have convergence you have stronger winds where you have divergence you have weaker winds one of the things i want you to also remember from chapter two the sun's direct rays move from the equator to 23.5 degrees north which is the tropic of cancer to 23.5 degrees south which is the tropic of capricorn so as the sun's direct rays continue to move these wind flows overall will move so for example in the united states summer this subtropical high will move a little further to the north so we tend to get much warmer air in our winter december january february that polar high tends to move south which means this polar front tends to move south so all that cold air to the north tends to move south so our air mass comes from canada in our winter our ams generally comes from the atlantic ocean and the gulf of mexico in our summer so we get different wind flows throughout the year so again look through pages 195 to page 203 you'll get an idea of this wind flow and this glow so again understanding the terminology understanding what the wind flow is and the naming convention at 90 degrees north you have the polar high from 90 degrees north to 60 degrees north you have the polar easterlies along 60 degrees north you have what we call the polar front or the subpolar low that's where we have convergence in the united states we have the wind flow called the westerlies where storms move from west to east and we get that westerly wind from the subtropical high which is located around 30 degrees north and then we have the northeast trade winds from 30 degrees north to the equator the equatorial low low pressure air is rising at the equator so as these air movements around the globe constantly move you can get different type of weather throughout the year so let's look back at the graphics here i have numerous graphics to give you an idea of where you have high pressure and low pressure this is just another one of them where you have high pressure at the north pole low pressure near 60 degrees north high pressure at 30 degrees north low pressure at the equator high pressure at 30 degrees south and then so forth going down low pressure at 60 degrees south and high pressure at 30 degree 90 degrees south so you can have constant moving of air around the globe so with that constant movement of air you're getting different weather features so this is one of the diagrams that is also in an e-textbook on pearson and also your physical textbook so one of the things i want you to notice at the north pole where it's very very cold you get sparse precipitation all year long it's not too cold to snow at the north pole it's too dry high pressure sinking air you don't get air rising you don't get condensation you don't get precipitation so high pressure sinking air at the north pole you get very little precipitation notice around 60 degrees north subpolar low the polar front that's converging air so air is rising you get condensation precipitation long island is located roughly around 42 degrees north 40 to 42 degrees north sao paulo ample precipitation in all seasons so we can get heavy rain november heavy snow in january heavy rain in april march june august september we have the chance of seeing ample precipitation all year long now we still get our droughts and our dry spells but in any given month we have a chance of getting wet weather because of the subpolar low and the polar front we have convergence near long island in the united states near canada we get rising air condensation precipitation now once you're around the sub tropical high since it fluctuates a little bit during the seasons you get some seasons that are dry some seasons that are wet and along the equator you get ample precipitation all year long again where low pressure is where you have low pressure you're going to get moisture where you have high pressure you tend to have less moisture so this is giving us an idea of what type of moisture we would have in the area so again going through chapter seven looking at these notes understanding global circulation and again this global circulation will fluctuate throughout the year here's the inter-tropical convergence zone remember the northeast trade winds meeting the southeast trade winds by the way this is the prime wind belt for hurricanes southeast trade winds meet the northeast trade winds into tropical convergence zone notice where it says january and july so notice it fluctuates a little bit around the globe as we go into the northern hemisphere summer the intertropical inversion zone moves north as we go into the winter in the northern hemisphere then tropical inverted zone moves south so low pressure and high pressures are constantly moving as incoming solar radiation changes throughout the year where the sun's direct rays are hitting throughout the year as well so again understanding how the wind flows now at the surface we have friction remember friction slows down the wind and the speed the corolla's force in the northern hemisphere deflects the wind to the right and the pressure gradient force pushes the wind from high pressure to low pressure pgf pressure gradient force wind flows from high pressure to low pressure in the united states wind flows from the west to the east now some of you may have heard of the jet stream the jet stream is above the ground it's roughly about 30 000 feet above the ground now that high up there's no friction the jet stream is going to be much faster than the winds at the ground the jet stream is also going to separate those polar easterly winds to your westerly warm winds so as it fluctuates throughout the year the jet stream is a wave in the atmosphere it'll fluctuate throughout the year it'll push warm and cold air to different places so let's look at this map here here's the jet stream this green arrow cold air to the north warm air to the south in the winter you have a bigger difference in pressure very high cold pressure up towards canada low pressure down near the equator the bigger the difference in pressure the stronger the winds you're going to have so for example in january minnesota could be 15 degrees below zero miami could be 75 degrees so you're talking 80 90 to almost 100 degree temperature difference in the winter so that's going to lead to a difference in pressure that's going to lead to stronger winds so the polar jet stream is stronger in the winter now in the summer jet stream is much weaker that's because you don't have a big difference in temperature remember a bigger difference in temperature will lead to difference in pressure that'll lead to difference in stronger or lighter winds so in the summer it could be 85 degrees in minnesota which is over northern united states and it could be 85 degrees in miami so there's not much of a temperature difference there or it could be you know 75 degrees in northern north dakota and it could be 90 degrees in miami so not a big temperature difference not a big pressure difference hence why the jet stream winds are weaker in the summer and stronger in the winter and the jet stream winds are also going to separate the cold air and the warm air so what we're going to be looking at this is a diagram from your book this is kind of what the jet stream looks like remember the winds are much stronger above the ground the jet stream winds tend to flow west to east in the united states they're much stronger they could be as high as 400 miles per hour above the ground there's no friction at 30 000 feet to slow down the wind the reason why we don't have 400 mile an hour winds of the ground friction it slows down the wind at the ground so here's your jet stream the cold air will be to the north the warm air will be to the south notice how there's little waves that's because high pressure and low pressure will be constantly moving and the wind will flow like little ripples so cold air to the north of the jet stream warm air to the south and what you can see here is that if you would have a little bit of a cold outbreak you would hear the meteorologist on tv or wherever else that there may be a little dip in the jet stream so that allows cold air to come out of canada into the united states and you can see that warm air so there's a constant flow of cold air and warm air around the globe so that's why it's very important to understand where we have these higher pressures and lower pressures so one of the things we're going to look at here the upper level winds or what you'll notice where it says flow aloft here flow aloft that's above the ground this is the jet stream it's roughly about 30 thousand feet now at the ground you can see high pressure and low pressure remember from chapter six go back and look at the diagrams where do we have convergent air at the surface and diverging air aloft converging at the surface diverging air aloft that's with low pressure so you see this red l down here at the surface cyclonic wind flow which is counterclockwise at the surface wind is flowing inward it is rising and diverging aloft so this is how we get these little ripples what we call ridges and troughs in the atmosphere troughs are associated with lower pressure and bad weather ridge associated with higher pressure and good weather so take a look at this where you have converging air at the surface you have rising air rising air leads to clouds and precipitation and from chapter five depending on how cold the air is it could be snow or sleet so rising air will lead to clouds and precipitation so where you have rising air you're going to have unsettled weather or bad weather where you have sinking air over higher pressure here's your anti-cyclonic wind flow or diverging air at the surface that's where we're going to get sunny weather conditions lighter winds with higher pressure stronger winds with lower pressure then above the ground we have these little dips and ridges so where we have these ridges above the ground they tend to bring the colder air down to the ground so where we have this little trough that brings in cold air to the ground where we have ahead of these troughs that's bringing warm air from the ground upward so there's a constant movement of warm air upward cold air downward so what meteorologists can look at where we have air constantly going up and down we can get an idea of where these storms are again these are all diagrams in your book and also in the pearson e textbook that we should be looking at so where we have low pressure notice you have warm air rising that will bring warm air upward you can get clouds and precipitation warm air rising cold air sinking cold infection behind low pressure warm air ahead cold air behind this is where you have a trough developing near high low pressure and you have a ridge near higher pressure so again troughs are with low pressure ridges are higher pressure ridges tend to have good weather okay and depending on where you are if you're on one side you'll have cold air advection if you're on the other side you'll have warm air advection so always constantly taking a look at that wind flow so just to recap okay low pressure convergence at the surface rises diverges aloft higher pressure has convergence aloft air sinks or substance air goes down hits the ground and then diverges out and this air is constantly moving around the atmosphere that's where we're looking at different things in the atmosphere to kind of go over so again the jet stream is going to be faster in the winter slower in the summer the jet stream will separate warm air and cold air also you have ridges and troughs with the jet stream and the movement of that air when flowing around higher pressure and lower pressure and in our global circulation understanding the wind flow what is it called at a certain location around the globe and when you have these wind flows throughout the you know most of the year these are called the prevailing winds so in the united states for long island our prevailing wind is generally more from a westerly direction that's why our weather here on long island is different than the weather out towards seattle or washington notice the red out here their wind flow is majorly off the pacific ocean there's a cold ocean current there so they tend to have more low clouds and moisture as opposed to us on the east coast our wind comes in off the land more often that's why we tend to be more dry than seattle washington so i hope you can appreciate that point that the wind flow in the united states west to east brings moisture to the west coast and then it dries out a little bit along the east coast but if our wind was ever to change our weather would be much similar to seattle's weather so again so understanding the major concepts here of chapter seven understanding the circulation of the atmosphere what are the winds called at certain areas around the globe the scales of motion micro scale meso scale okay planetary scale synoptic scale synoptic scale weather maps that's one of the things that we look at synoptic scale weather maps by the way these are synoptic scale weather maps where you have high pressures and low pressures those are synoptic scale weather maps that we can see what's going on these weather maps are synoptic scale weather maps they show high pressures low pressures and they show wind flow around systems due to the isobars so a lot of different things that are going on there so again in chapter seven understanding the global circulation one of the things you want to look at pages 195 to page 205 that'll go over more of this global circulation so again you can see near 90 degrees north that's the polar high all the way down towards the southeast trade winds which is at 30 degrees south so make sure you understand those wind flows and understand precip precipitation where we're going to get the most types of precipitation throughout the year near 60 degrees north near four degrees north where we are we're going to get ample precipitation throughout the year so that's my class notes please read through chapter 7.