hi everyone welcome to the earth science region review podcast series created by homk Middle School earth science department today we're going to talk about weather fronts well before we get into fronts we got to talk a little bit about clouds first clouds form when warm air is going to rise as warm air rises through the troposphere it's going to cool off but due to the lack of pressure the air mass is going to expand so it's a special type of cooling called expansional cooling it's going to cool to the dupoint and at that dupoint you're going to get cloud formation condensation and evitably you'll get some precipitation as well well clouds don't form in thin air they have to form on a Surface Now dust pollen pollution whatever little objects you have in the atmosphere water droplets can can uh condense onto those are what we call condensation nuclei now clouds are made up of billions upon billions of water droplets with condensation nuclei at the very center so you see the average size they are really literally microscopic pieces in the atmosphere now warm air we had mentioned Rises now there's three different ways in which it can rise the first way is what we call orographic lifting sometimes warm air masses are going to come off the ocean and they're going to come in contact with the mountain range the easiest way for an air mass to go around a mountain range is to go up and over it well again because of the fact that it's cooler in the upper atmosphere your air mass is going to is going to condense at the dup point and that's where you're going to get your massive precipitation the side of the mountain that gets the precipitation is called the windward side of the mountain that's going to be the side and that's all caused by again that expansional Cooling in the upper atmosphere well once that air mass drops off all of its moisture on the windward side it's very cold and dry now so it's going to descend down the leeward side of the mountain because it's a little bit more dense now as it sinks down the leeward side of the mountain it starts to heat up because the pressure is starting to become greater as you travel down the mountain side that's what we call compressional heating now because the air mass is so dry we say that the leward side of the mount Mountain has what's called a rain shadow effect because the number of deserts on the rain shadow effect Side of the Mountain then we call that the leeward side so you look at the diagram left side of the mountain is the windward the right side of the mountain is going to be the Lee word and again you see the cloud formations that are formed due to this orographic lifting the second way is through convective lifting and by now you should have an idea about what convection is it's all about density differences warm air rises and cold air sinks and this constant circulation now is what we call convection if you're not sure please check out my other podcast in the series because we do get into a little bit more detail about what convection is all about the Third Way is what we call frontal wedging and this is when a warm air mass and a cold air mass are going to collide with each other anytime there's a little struggle between them warm air always loses and gets forced upward and again it's going to cool to the dupoint clouds and precipitation form at the point where frontal wedging actually occurs now there are some different air masses Within the continental United States and North America that are going to collide with each other and interact you have empti air masses which are maritime tropical you have MP air masses which are maritime polar CP or CA air masses which are content Arctic or continental polar and then ctrss which are Continental Tropical notice that some are wet some are dry some are hot some are cold you definitely need to know the characteristics now each air mass gets its own individual characteristics from the source region which it comes from so if your air mass forms over the Pacific in the north it's going to be maritime polar if it forms over Canada continental polar or Continental Arctic forms over the Southern Pacific Gulf of Mexico or Southern Atlantic maritime tropical or in the continental US around the Four Corners region or Mexico Continental Tropical so very important to understand the source regions in which those air masses come from so basically front a boundary between two air masses and we have cold warm stationary and occluded and what's important here is that each front has its own individual characteristics please notice the symbols they're actually in page 13 in your reference table the symbol itself is going to tell you the direction of motion cold uded warm front those are no problem because they're actually moving in some sort of Direction stationary front they don't move because you get air masses colliding with each other in opposite directions so let's start out with the cold front this is where a cold air mass is trying to overtake a warm air mass what happens here is that you tend to get very heavy precipitation tornadoes you tend to get thunderstorms very simply because you get a very quick change in the atmosphere cold fronts travel very quickly so they force that warm air up so rapidly condensation is so violent you get that nasty precipitation right at the frontal boundary once that air mass travels through though you get higher pressure cooler temperatures and much much drier air so you can see that the here's your highlighted region for the front before the front you have the warm air behind the front you have the cold air the boundary you notice it's a very steep boundary which represents you have a very very quick change in atmospheric conditions the rapid condensation the rapid lifting of the warm air dramatic precipitation right at the frontal boundary warm fronts are the exact opposite here's where a warm air mass trying to overtake a cold air mass you tend to get gradual precipitation usually occurs over a couple days so if you tend on if you tend on getting a uh warm front on Wednesday you're going to get precipitation probably Monday night into Tuesday very gradual precipitation because the warm air lifting is not as violent once that warm air mess passes through what's going to happen is you're going to get lower pressure little bit warmer temperatures and a little bit moiser air so you'll see before the front you have the cold air behind the front you have the warm air here's your frontal boundary there you notice that the precipitation occurs before the frontal boundary actually comes through very slow gradual precipitation so there's your cold front on the left you'll see the cold air is going to be coming down from Canada so you see the temperatures in the 20s the 30s the 40s you see the warm air mess they traveling in a Northwest direction and what's going to happen here is your warm air in the 60s and 50s are going to be traveling in a Northwest Direction the reason why they're traveling like that because low pressure goes into a counterclockwise rotation Auda front or your mid latitude Cyclones this is where your cold front and warm front actually meet up with each other and they merge together they zip together you are going to get major major precipitation with these types of Storms and what's going to happen here is when you look at a satellite image you're going to notice a mid- latitude cyclone because of the classic Comm cloud and you'll notice in this picture from 1998 the classic Comm Cloud extends from Minnesota all the way down into the Gulf of Mexico now on the left hand side that is your mid latitude cyclone on the right hand side that's your occluded front the mid latitude cyclone hasn't zipped together yet the occluded front it has zipped together that's why you have the purple head to that specific front because you see the merging of the warm front and the cold front now you see here the cold air is on the left the cool air is on the right the warm air is in the middle the cold air catches up to the cool air forcing that warm air up very rapidly and you get a significant amount of precipitation with that rapid rising of warm air so again you can see on the left hand side that's a mid latitude cyclone about to zip together into an uded front there's your there's the temperature between the cold front and the warm fronts so you see the big major warm sector there and in this picture you can actually see the occlusion that is actually taking place the last type of front is what we call stationary front and this is where warm front cold front is going to collide together they kind of battle for Supremacy so they kind of stall out and they don't move until one of the fronts actually weakens out and you tend to get a little precipitation here because warm air does rise up a little bit but they are a little bit battling here for supremacy of the area so you'll see the the picture on the left shows you the uh stationary front symbol on the right hand side shows you what it might look like from inside as well and again here's a weather map that just gives you an idea in terms of where a stationary front might be located and the different characteristics with it so with that being said that was a quick tutorial on some of your weather fronts please make sure you understand the characteristics of them please make sure you go out and you practice your weather maps and know how to forecast because when it comes region time a lot of your questions are going to be related to weather maps themselves with mid latitude Cyclones or uded fronts on them so please make sure you know them so that's it for now thanks for joining me and we'll talk to you soon