Air Masses & Fronts - LCPS
12/14/2010Air Masses &FrontsWeatherAll weather is a result of humidity,condensation and pressure.1
12/14/2010VirginiaGlobalWindPatternsWeather Movement in theContiguous United StatesWe are in the prevailing westerly windbelt, so our weather tends to move fromthe southwest to the northeast.2
12/14/2010Map #1Map #2Map #3Map #4Formation of Waves on SurfaceWaterWind blowing over water produceswaves.3
12/14/2010Formation of Surface OceanCurrentsThe direction of ocean currents isaffected by the prevailing windsbecause the wind blows over the watercausing the currents.Currents tend to spin clockwise in theNorthern Hemisphere andcounterclockwise in the SouthernHemisphere (due to the Coriolis Effect)4
12/14/2010Air MassA large body of air in the lower tropospherethat has similar characteristics throughoutTemperature & humidity depend on originand move with the air massTypes of Air MassesContinental dryContinental:Maritime: wetMaritimePolar: coldTropical: warmcontinental polar (cP): cold & dry (Canada)continental tropical (cT): warm & dry (Mexico)maritime polar (mP): cold & wet (north oceans)maritime tropical (mT): warm & wet (south oceans)5
12/14/2010Types of Air MassesLocal Air Masses6
12/14/2010Weather ExampleContinentalPolarContinentalTropicWeather ExampleCold & dry(no precip)7
12/14/2010FrontsFront- an interface or boundary between 2air masses of different characteristicsFrontsCold Front: boundary between advancing cold air mass & awarmer air mass it is displacing/pushing aside Rising warm air usually produces precipitation if wetAir becomes colder after front passesSteep slopes, rapid changes in weather, thunderstorms, hail, tornadoes8
12/14/2010FrontsWarm Front: boundary between advancing hot air mass & acolder air mass it is displacing/pushing aside 1st clouds days in advance, then RAINAir becomes warmer after front passesGentle slope, long periods of precipitation and layered cloudsFrontsOccluded Front: when cold front ‘catches up’ to awarm front, producing clouds & precipitation as thewarmer air mass between them is forced to rise Forms mid-latitude cyclones (lows)9
12/14/2010Forming an Occluded FrontFrontsStationary front: when a front stops movingforward, producing clouds & precipitation –causes floods if stationary too long10
12/14/2010Fronts and Weather MapsFront Symbols (the symbols point in thedirection the front is moving)Locating a FrontWind direction changesTemperature changes sharplyDew Point changes sharply11
12/14/2010ID That Front!Air Temperature changing as front dfrontch/TAIR10171996.mov)Dew Point Temp changing as front dfrontch/TDEW10171996.mov)Wind Direction changing as front dfrontch/WIND11061996.mov)What type of front is this?Keys to WeatherForecasting(1) Storms move southwest to northeastin US(2) L is stormy, winds arecounterclockwise (low pressure)(3) H is clear, winds are clockwise (highpressure)(4) Precipitation forms near the center of aL and along a front12
12/14/2010Where would precip be?13
Air Masses & Fronts Weather All weather is a result of humidity, condensation and pressure. 12/14/2010 2 Global Wind Patterns Virginia Weather Movement in the Contiguous United States We are in the prevailing westerly wind . Microsoft PowerPoint -
o Air masses of North America Fronts o Stationary fronts o Cold fronts o Warm fronts o Fronts and the jet stream o Frontogenesis o Drylines o Occluded fronts . - transient weather systems (Rossby waves) - small scale f
Fronts are the boundaries between two air masses. Fronts are the basic building blocks of weather systems. Fronts occur where two large air masses collide at the earth's surface. Each air mass has a different temperature associated with it. Fronts are caused by winds moving one air mass
air masses as they form is important to resulting weather conditions when air masses move. Fronts As these air masses move and collide with each other, fronts form at the boundaries between the air masses. Depending upon the air masses involved, a warm front, cold front, st
fronts o fronts: a boundary between air masses there are three types of fronts o cold fronts: move quickly. cold air pushes against warm air, causing the warm air to rise. cumulus clouds heavy storms a
Occluded fronts bring cool temperatures and large amounts of rain and snow. Warm air mass Cold air mass Cold air mass Warm air mass Movement of front Occluded front Occluded front An occluded front forms when a warm air mass is trapped between two cold air masses. The cold air masses move together and push the warm air out of the way .
Occluded fronts bring cool temperatures and large amounts of rain and snow. Warm air mass Cold air mass Cold air mass Warm air mass Movement of front Occluded front Occluded front An occluded front forms when a warm air mass is trapped between two cold air masses. The cold air masses move together and push the warm air out of the way .
Air masses that form near the equator are called tropical air masses. Those air masses that form in cold regions are called polar air masses. Air masses that form near the poles are called arctic and antarctic air masses. Visual Check 2. Classify Where does continental polar air come fro
Stationary fronts behave like warm fronts, but are more quiescent. Many times the winds on both sides of a stationary front are parallel to the front and have opposite direction. Typically stationary fronts form when polar air masses are modified significantly so as
