WednesdayWednesday, , November 16th November 16th

AttendanceAttendance Go over Unit Test 3Go over Unit Test 3 Make-up work Make-up work

and/or weather dvdand/or weather dvd

Unit 11Unit 11

Weather ForecastingWeather Forecasting

I. Weather MapsI. Weather Maps

A. A. SynopticSynoptic forecasting is based forecasting is based on looking at a summary of the on looking at a summary of the total weather picture at a total weather picture at a particular time.particular time.– A A synoptic synoptic weather map is made by weather map is made by

measuring atmospheric weather measuring atmospheric weather variables at thousands of weather variables at thousands of weather stations around the world.stations around the world.

I. Weather MapsI. Weather Maps B. B. FieldField – a region of space that has – a region of space that has

a measurable quantity at every point.a measurable quantity at every point.– Elevation Elevation is measured by is measured by contour linescontour lines

on a topographic map.on a topographic map.– TemperatureTemperature is measured by is measured by isothermsisotherms

on a weather map.on a weather map.– Atmospheric pressureAtmospheric pressure is measured by is measured by

isobarsisobars on a weather map. on a weather map.– IsolinesIsolines are “generic” lines that connect are “generic” lines that connect

equal values.equal values.

I. Weather MapsI. Weather Maps C. C. Air massesAir masses are large regions of air with are large regions of air with

fairly uniform characteristics like fairly uniform characteristics like temperature, humidity, winds and air temperature, humidity, winds and air pressure.pressure.– Identified by the temperature and moisture Identified by the temperature and moisture

content.content.– The code has two letters.The code has two letters.

The first letter is lower case and represents moisture.The first letter is lower case and represents moisture.– m = maritime = moistm = maritime = moist– c = continental = dryc = continental = dry

The second letter is upper case and represents The second letter is upper case and represents temperature.temperature.

– T = tropical = warmT = tropical = warm– P = Polar = coolP = Polar = cool– A = Arctic = frigid (very cold)A = Arctic = frigid (very cold)

I. Weather MapsI. Weather Maps

C. Air MassesC. Air Masses– The boundaries between air masses The boundaries between air masses

are called frontal boundaries. are called frontal boundaries. FRONTSFRONTS

– What causes air masses to move What causes air masses to move across the Earth?across the Earth?

I. Weather MapsI. Weather Maps

Answer: Planetary windsAnswer: Planetary winds

I. Weather MapsI. Weather Maps

D. Weather FrontsD. Weather Fronts– There are usually several different There are usually several different

air masses moving across the United air masses moving across the United States.States.

– When different air masses meet, When different air masses meet, very little ______ occurs.very little ______ occurs. There is a frontal boundary and there is There is a frontal boundary and there is

a rapid change in the weather. It is a rapid change in the weather. It is usually unsettled and rainy.usually unsettled and rainy.

1. Weather Maps1. Weather Maps D. Weather FrontsD. Weather Fronts

– There are 4 main types of frontal There are 4 main types of frontal boundariesboundaries

– 1. 1. Cold FrontsCold Fronts occur when cold air moves occur when cold air moves in on warmer air.in on warmer air. The cold air is more dense and stays near the The cold air is more dense and stays near the

ground as it pushes up the warmer air in its ground as it pushes up the warmer air in its way.way.

The warm air that is pushed up cools. It can The warm air that is pushed up cools. It can no longer hold as much water vapor and no longer hold as much water vapor and heavy precipitation heavy precipitation occurs.occurs.

I.I. Weather MapsWeather Maps

D. FrontsD. Fronts2. 2. Warm FrontsWarm Fronts occur when a warm occur when a warm

air mass runs into a cold air mass.air mass runs into a cold air mass.

The warmer air is forced up and it The warmer air is forced up and it cools. It can no longer hold as much cools. It can no longer hold as much water vapor.water vapor.

Heavy precipitationHeavy precipitation occurs. occurs.

I.I. Weather MapsWeather Maps

D. FrontsD. Fronts 3. 3. Stationary FrontsStationary Fronts occur along the occur along the

boundary between a warm air mass boundary between a warm air mass and a cold air mass when neither and a cold air mass when neither move.move.– The warm air will eventually move on The warm air will eventually move on

top of the cold air and there will be top of the cold air and there will be precipitationprecipitation for a few days until a new for a few days until a new front moves in.front moves in.

I. Weather MapsI. Weather Maps

D. FrontsD. Fronts 4. 4. Occluded FrontsOccluded Fronts occur when a occur when a

cold air mass runs into another cold air mass runs into another cold air mass (a warm air mass cold air mass (a warm air mass might be stuck between them).might be stuck between them).– Since cold air masses are more Since cold air masses are more

dense, they travel faster.dense, they travel faster.– Large scale Large scale precipitationprecipitation occurs. occurs.

I. Weather MapsI. Weather Maps E. E. CyclonesCyclones are low pressure systems. are low pressure systems.

I.I. Weather mapsWeather maps F. F. AnticyclonesAnticyclones are high pressure are high pressure

systems.systems.

I. Weather mapsI. Weather maps

G. G. Jet StreamsJet Streams are bands of easterly are bands of easterly moving air made by convection cells within moving air made by convection cells within the atmosphere. The winds can blow up to the atmosphere. The winds can blow up to 200 mph. Jet streams help steer weather 200 mph. Jet streams help steer weather patterns across our continent.patterns across our continent.

II. Weather II. Weather ForecastingForecasting SynopticSynoptic weather forecasting uses weather forecasting uses

charts, maps and computers.charts, maps and computers. StatisticalStatistical weather forecasting looks weather forecasting looks

at past weather frequency.at past weather frequency. Weather patterns become evident Weather patterns become evident

when weather variables are when weather variables are observed, measured and recorded.observed, measured and recorded.

II. Weather II. Weather ForecastingForecasting _________ is Radio Detection And _________ is Radio Detection And

Ranging bounces electromagnetic Ranging bounces electromagnetic energy off of clouds to get images energy off of clouds to get images on a computeron a computer

Doppler RadarDoppler Radar is a special type of is a special type of radar that gives accurate readings radar that gives accurate readings and is able to determine the and is able to determine the conditions necessary for tornadoesconditions necessary for tornadoes

II. Weather II. Weather ForecastingForecasting _____________ images show the position _____________ images show the position

of clouds and storms as they travel over of clouds and storms as they travel over the earth.the earth.

III. Energy in the Atm.III. Energy in the Atm.

Earth’s systems have internal and Earth’s systems have internal and external heat enginesexternal heat engines– InternalInternal: friction, radioactivity, : friction, radioactivity,

residual heat from formationresidual heat from formation– ExternalExternal: sun’s heat, trapped Earth’s : sun’s heat, trapped Earth’s

heatheat

III. Energy in the Atm.III. Energy in the Atm.

Precipitation results from the heating of Precipitation results from the heating of the atmposphere from the sun.the atmposphere from the sun.

The transfer of energy from the The transfer of energy from the atmosphere, hudrosphere and th atmosphere, hudrosphere and th eEarth’s interior results in the formation eEarth’s interior results in the formation of regions with different densities.of regions with different densities.

Density differences between regions Density differences between regions results in the motion of air and weather.results in the motion of air and weather.

IV. Hazardous WeatherIV. Hazardous Weather

The loss of property, personal injury The loss of property, personal injury and loss of life can be reduced by and loss of life can be reduced by effective emergency preparedness.effective emergency preparedness.

IV. Hazardous IV. Hazardous WeatherWeather ThunderstormsThunderstorms

– Updrafts and down drafts of air occur Updrafts and down drafts of air occur because of unequal heatingbecause of unequal heating

– Particles of air build up electrical Particles of air build up electrical charges as the air goes up and downcharges as the air goes up and down

– Lightening occurs because of the Lightening occurs because of the electrical chargeselectrical charges

– **Stay away from trees, don’t use **Stay away from trees, don’t use electrical appliances, don’t use electrical appliances, don’t use plumbingplumbing

IV. Hazardous IV. Hazardous WeatherWeather ____________ are small, brief ____________ are small, brief

disturbances that usually develop disturbances that usually develop over land from intense over land from intense thunderstormsthunderstorms– Hot moist air meeting with cold, dry Hot moist air meeting with cold, dry

airair– Narrow: 100 feet in diameterNarrow: 100 feet in diameter– Can last up to an hourCan last up to an hour– Wind speeds up to 320 mphWind speeds up to 320 mph– Occur in spring and summerOccur in spring and summer– ********Go into the basement and cover Go into the basement and cover

your head, stay away from windows.your head, stay away from windows.

IV. Hazardous IV. Hazardous WeatherWeather ________________ are regions of ________________ are regions of

very low pressure, cyclones, that very low pressure, cyclones, that form over open water, huge form over open water, huge swirling wind massswirling wind mass

Lose energy as travels over landLose energy as travels over land Winds of 74 mph or more, storm Winds of 74 mph or more, storm

surges, causes massive floodingsurges, causes massive flooding June to NovemberJune to November ******EvacuateEvacuate