Objectives Define and described air masses l Define

Objectives Define and described air masses. l Define and describe weather fronts. l Be able to name winds and air masses l Understand differing cyclonic systems and how to prepare for related emergencies. l Compare high and low pressure systems. l Read, label and analyze a weather map. l

Air Masses l Large areas (blobs) of air that have the same weather, temperatures and humidity and air pressure l Air Mass Types - Named for where they come FROM l Weather changes occur with changes in air masses

TYPES of Air Masses The Bergeron Classification System maritime Tropical (m. T)- humid/moist air & warm l continental Tropical (c. T)- dry air & hot l maritime Polar (m. P)- humid/moist air & cold l continental Polar (c. P)- dry air & cold l continental Arctic (c. A)- dry air & very cold l l There are no m. A air masses

Fronts l boundary between two air masses l bring changes in the weather (from west to east) l Fronts are named for the air that is behind them

Air Mass Army Analogy l Think of air masses as an army front (the army is BEHIND the frontline) l At the Front there is FIGHTING and lots of VIOLENCE (stormy weather) l Behind the front (inside the air mass) the general sits on his duff and watches the goings-on while enjoying the nice weather!

NICE WEATHER FIGHTING - STORMS

Cold Front l l Cold dense air pushes warm air out of the way Cold fronts move very quickly and bring short periods of rain/thunderstorms Lower temperatures are behind the front SYMBOL – the direction of the “arrows” points towards the direction the front is MOVING

Warm Front l l Warm air moves up the cold front as it slowly displaces the cold air Warm fronts move slowly, and bring many days of steady precipitation Higher temperatures are behind the front SYMBOL – direction of “half-moons” is the direction the front is moving

Stationary Front l l l The air from the warm front and cold front meet, but do not move These fronts have the same weather as warm fronts SYMBOL – warm and cold fronts are moving in opposite directions, thus making a stationary condition

Occluded Fronts Sometimes a colder or cooler front follows right behind a warmer front. A warm air mass pushes into a colder air mass (the warm front) and then another cold air mass pushes into the warm air mass (the cold front). Because cold fronts move faster, the cold front is likely to overtake the warm front. This is known as an occluded front. Remember moving in the same direction and combind or included.

There are two types of Occlusion I. In a cold occlusion, the air mass overtaking the warm front is cooler than the cool air ahead of the warm front, and plows under both air masses II. In a warm occlusion, the air mass overtaking the warm front is not as cool as the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air.

Vocabulary Prevailing Westerlies- typical west wind at this latitude l Trade winds- prevailing wind from east below Florida's latitude l Jet stream- high altitude, high speed “river of air” l Storm track- path of a storm l

The Cyclone l. A Cyclone is any low pressure system that has a counterclockwise rotation l(In the Northern Hemisphere)

Types of Cyclones: Tornado- a small, compact storm with strong winds l AKA: l l Twister l Willy-Willy (Australia)

Types of Cyclones Hurricane- A large, organized storm with strong winds and heavy rain l AKA l l Typhoon- in the Pacific

Types of Cyclones Mid Latitude Low- a low pressure system in the middle latitudes l We live in the middle latitudes (30 -50 degrees North & South) l Comma shaped l AKA l l Nor’ , Easter (North Easter) l Alberta Clipper

Prevailing Winds Push weather around l In N. C. , the prevailing winds come from the west l Most of the time our winds come from the west l (therefore) our weather will usually come from the west l Sometimes we will get wind from the Northeast, which usually brings extreme weather. “Nor’ easters” l

A nor'easter is a type of macro-scale storm along the East Coast of the United States and Atlantic Canada, so named because the winds come from the northeast atlantic, especially in the coastal areas of the Northeastern United States and Atlantic Canada. But their reach can be down into the atlantic southeast. The precipitation pattern is similar to other extratropical storms. Nor'easters also can cause coastal flooding, coastal erosion, hurricane force winds, and heavy snow. Nor'easters can occur at any time of the year but are mostly known for their presence in the winter season

Windward and Leeward Winds Rain Shadow Windward Side Leeward Side

A rain shadow is a dry area on the mountainside facing away from the direction from which the wind comes. The mountains block the passage of rainproducing weather systems, casting a "shadow" of dryness behind them. Warm moist air is "pulled" by the prevailing winds over a mountain. Then it condenses and precipitates and the dry air moves foreword leaving a rain shadow behind the mountain. Usually a desert.

Surface Winds

The Mid Latitude Low N This weather system starts when cool and warm air masses meet. Then a Low develops over the interface. S

The Low continues to spin, creating a warm front and a cold front.

Rain will fall in front of the warm front and right on top of the cold front.

Hurricanes Massive storms with a size that can be more than 300 miles in diameter. l Feed on warm water l Biggest danger is the storm surge in coastal areas l

High Pressure Cells l l A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. High-pressure areas are generally associated with cooler, drier air as well as clearing skies due to their formation within areas of atmospheric subsidence, or areas of large scale air descent. A low pressure area is commonly associated with inclement weather, while high pressure area is associated with light winds and fair skies. Clockwise

Low Pressure Cells l l l Wind is initially accelerated from areas of high pressure to areas of low pressure. [ Stronger areas of low pressure associated with stronger winds. The stronger the pressure difference, or pressure gradient, between a high pressure system and a low pressure system, the stronger the wind A low pressure area is commonly associated with inclement weather, while high pressure area is associated with light winds and fair skies. Counter-clockwise

High and Low Pressure

Rough surf hundreds of miles away. Hurricane far off shore Storm Surge

Hey! Let’s check out the storm!

Hurricane Tracks

Tornadoes form from very powerful thunderstorms (cumulonimbus clouds) l These are funnel shaped columns of spiraling winds that extend down to the ground from the base of a cloud l The winds move into a tornado (low pressure), and can reach a maximum of 318 mph! l Spin COUNTER CLOCKWISE (like a hurricane) l The actual funnel is made by water droplets (clouds) and dust l

Tornadoes are especially dangerous because it is so difficult to predict where they will form l Damage is usually along a narrow path where the tornado traveled l They usually last less then one hour l Most fatalities are caused by flying debris l Tornadoes are rated on the Fujita scale (F 0 – F 6) l An F 6 is very rare, and can have wind speeds up to 318 mph l

TORNADOES!

Tornadoes will pick up dust and debris from the ground when then “touch down” – this creates a wider swirl at the bottom of the tornado

For those of you who aren't familiar with tornadoes, here is a short glossary to help you understand. Fujita Scale: Scale used to measure wind speeds of a tornado and their severity. F 1: Laughable little string of wind unless it comes through your house, then enough to make your insurance company drop you like a brick. People enjoy standing on their porches to watch this kind. F 2: Strong enough to blow your car into your house, unless of course you drive an Expedition and live in a mobile home, then strong enough to blow your house into your car.

F 3: Will pick your house and your Expedition up and move you to the other side of town. F 4: Usually ranging from 1/2 to a full mile wide, this tornado can turn an Expedition into a Pinto, then gift wrap it in a semi truck. F 5: The Mother of all Tornadoes, you might as well stand on your front porch and watch it, because it's probably going to be quite a last sight. F 6: Is theoretical and has never been reported. It is known as “the finger of god’ or “the finger of fate. ” The implication, is that the power and

Meteorologist: A rather soft-spoken, mild-mannered type person until severe weather strikes, and they start yelling at you through the TV: "GET TO YOUR BATHROOM OR YOU'RE GOING TO DIE!“ Storm Chaser: Meteorologist-rejects who are pretty much insane but get us really cool pictures of tornadoes. We release them from the mental institution every time it starts thundering, just to see what they'll do. Moore, Oklahoma: A favorite gathering place for tornadoes. They like to meet here and do a little partying before stretching out across the rest of the Midwest.

Bathtub: Best place to seek shelter in the middle of a tornado, mostly because after you're covered with debris, you can quickly wash off and come out looking great. Severe Weather Radio: A handy device that sends out messages from the National Weather Service during a storm, though quite disconcerting because the high pitched, shrill noise just as an alarm sounds suspiciously just like a tornado. Plus the guy reading the report just sounds creepy. Tornado Siren: A system the city spent millions to install, which is really useful, unless there's a storm or a tornado, because then of course you can't hear them.

Storm Cellar: A great place to go during a tornado, as it is almost 100% safe, though weigh your options carefully, as most are not cared for and are homes to rats and snakes. May-June: Tourist season in Oklahoma, when people who are tired of bungee jumping and diving out of airplanes decide it might be fun to chase a tornado. These people usually end up on Fear Factor.

Mobile Home: Most people are convinced mobile homes send off some strange signal that triggers tornadoes, because if there's one mobile home park in a hundred mile radius, the tornado will find it. Twister: Slang for 'tornado' and also the title to a movie starring Helen Hunt, which incidentally everyone thought was corny and unrealistic until May 3 rd, 1999.

TORNADO RECORDS · Highest Recorded Wind: 318 mph, Bridge Creek/Moore, OK, May 3, 1999. ** · Widest Observed Path: 2. 5 miles, Hallam, NE, May 22 nd, 2004. + · Longest Observed Path: 219 miles, Tri State Tornado, March 18, 1925.

Additionally, here are some phrases you might want to learn and be familiar with: "We'll have your electricity restored in 24 hours, " which means it'll be a week. “We're going to be out for a week, so buy a lot of supplies and an expensive generator, " means it's going to be on in twelve hours, probably as soon as you return from Wal-Mart. "It's a little muggy today. " Get outta town. It's getting ready to storm. "There's just a slight chance of severe weather today, so go ahead and make your outdoor plans. " Ha. Ha ha ha ha.

The BIG STORM TIP of the day: When your electricity goes out, and you go to bed at night, be sure to turn off everything that was on before it went out, or when it is unexpectedly restored in the middle of the night, every light, every computer, your dishwasher, your blow dryer, your washing machine, your microwave and your fans will all come on all at once. 1) You'll just about have a heart attack when they all come on at the same time, waking you from a dead sleep. And 2) Your breakers will blow, leaving you in the dark once again.

• small area storms formed by the strong upward movement of warm, moist air • usually occurs ahead of a cold front as the colder, denser air shoves the warmer air upward • This forms the cumulonimbus clouds that produce thunderstorms • These storms are accompanied by heavy rain, thunder, lightning, sometimes hail, and can also produce tornadoes

All thunderstorms produce lightning l Lightning is the discharge of huge amounts of static electricity (think of walking across a carpet in your socks and then touching something-ZAP) l Lightning can travel from the cloud to the ground, cloud to cloud, or even from the ground to a cloud! l Thunder is the result of the air quickly expanding from the heat of the lightning bolt (causes a sound wave) l You cannot have lightning without thunder!! l

Supercell Thunderstorm formations – will form SEVERE storms and tornadoes! THIS IS ONE BIG STORM SYSTEM!

European Storms: http: //www. youtube. com/watch? v=68 d 2 Efe. HYf A&safety_mode=true&persist_safety_mode=1 NWS Hurricane Plane: http: //www. youtube. com/watch? v=a. Oakt. KIo. VX 8 NOAA 1988: Weather Plane http: //www. youtube. com/watch? v=KWVMc. LQio. Qs&feat ure=related

Videos/Games Grade Swap l http: //reviewgamezone. com/game. php? id= 1838 Air Mass Video l http: //www. youtube. com/watch? v=Kmhizd 4 De 2 E&safety_mode=true&persist_safety _mode=1&safe=active