MeteorologyMeteorology

What is Meteorology?What is Meteorology?

• MeteorologyMeteorology is the study of is the study of atmospheric phenomenaatmospheric phenomena

• Anything that’s high in the sky: Anything that’s high in the sky: raindrops, rainbows, dust, raindrops, rainbows, dust, snowflakes, fog and lightning snowflakes, fog and lightning

• All of these are examples of All of these are examples of meteors?meteors?

What is Meteorology?What is Meteorology?

• Atmospheric phenomena are Atmospheric phenomena are classified as types of meteorsclassified as types of meteors

• Cloud droplets (rain, sleet, snow) are Cloud droplets (rain, sleet, snow) are types of types of hydrometeorshydrometeors..

• Smoke, haze, dust – any particles Smoke, haze, dust – any particles suspended in the atmosphere are suspended in the atmosphere are lithometeorslithometeors..

What is Meteorology?What is Meteorology?

• Short term variations in atmosphere Short term variations in atmosphere phenomena that affect the phenomena that affect the environment and life on Earth is environment and life on Earth is weatherweather..– These variations can be minutes, hours, These variations can be minutes, hours,

days, weeks up to years long.days, weeks up to years long.

• ClimateClimate is the long term average in is the long term average in weather for a particular areaweather for a particular area

Heating Earth’s SurfaceHeating Earth’s Surface

• Sunlight is always heating some part Sunlight is always heating some part of Earthof Earth

• Over time the amount of thermal Over time the amount of thermal energy Earth gets is the same energy Earth gets is the same amount that Earth radiates back to amount that Earth radiates back to space.space.

• How is this solar radiation distributed How is this solar radiation distributed around Earth?around Earth?

Imbalanced HeatingImbalanced Heating

• In January, which is warmer? Miami In January, which is warmer? Miami or New York City?or New York City?

• One reason is that Earth is tilted. One reason is that Earth is tilted. Miami gets more solar radiation in Miami gets more solar radiation in January.January.

• Another is that Earth is a sphere and Another is that Earth is a sphere and different places are at different different places are at different angles to the sun.angles to the sun.

Thermal Energy Thermal Energy RedistributionRedistribution

• Places on Earth maintain about the Places on Earth maintain about the same average temperatures over same average temperatures over time due to the movement of air and time due to the movement of air and water between land, water and water between land, water and atmosphere.atmosphere.

Air MassesAir Masses

• An An air massair mass is a large volume of air is a large volume of air with the same humidity and with the same humidity and temperature as its source region.temperature as its source region.

• A A source regionsource region is the area where is the area where an air mass forms.an air mass forms.

• Most form over tropical waters or Most form over tropical waters or polar regions.polar regions.

Types of Air MassesTypes of Air Masses

• Tropical air masses form in tropical Tropical air masses form in tropical bodies of water and are responsible bodies of water and are responsible for our hot, humid summersfor our hot, humid summers

• Polar air masses form over the cold Polar air masses form over the cold waters of the North Atlantic and waters of the North Atlantic and North Pacific. These bring our really North Pacific. These bring our really cold air in winter.cold air in winter.

• The flip side?The flip side?

Learning Targets

•Compare and contrast weather vs climate

•Analyze how imbalances in the heating of Earth’s surface create weather

• Identify five types of air masses and explain how air masses form

Global Wind SystemsGlobal Wind Systems

• If the Earth didn’t rotate, two large If the Earth didn’t rotate, two large convection currents would cover the convection currents would cover the Earth.Earth.

• Colder air would sink to the tropics Colder air would sink to the tropics where it would force warm air to rise.where it would force warm air to rise.

• This air would cool as it got higher This air would cool as it got higher and on and onand on and on

Global Wind SystemsGlobal Wind Systems

• Earth rotating from west to east Earth rotating from west to east prevents this from happening.prevents this from happening.

• The directions of our winds are The directions of our winds are influenced by the Earth’s rotation.influenced by the Earth’s rotation.

• Its called the Its called the Coriolis effectCoriolis effect..

Coriolis EffectCoriolis Effect

• Causes fluids and objects to move in Causes fluids and objects to move in a curved path.a curved path.

• Moving air curves to the right in the Moving air curves to the right in the northern hemisphere northern hemisphere

• Moving air curves to the left in the Moving air curves to the left in the southern hemispheresouthern hemisphere

•http://www.youtube.com/watch?v=mcPs_OdQOYU

Global Wind SystemsGlobal Wind Systems

• The Coriolis effect and the heat The Coriolis effect and the heat imbalance on Earth create distinct imbalance on Earth create distinct global wind systems.global wind systems.

• There are three main zones or wind There are three main zones or wind systems: polar easterlies, prevailing systems: polar easterlies, prevailing westerlies and trade winds.westerlies and trade winds.

Global Wind SystemsGlobal Wind Systems

• Polar easterliesPolar easterlies– Between 60Between 60oo N latitude and the north N latitude and the north

pole and 60pole and 60oo S latitude and the south S latitude and the south polepole

– Begin as dense polar air that sinksBegin as dense polar air that sinks– As the Earth spins, this cold air is As the Earth spins, this cold air is

deflected in an easterly direction: deflected in an easterly direction: usually weak and sporadicusually weak and sporadic

Global Wind SystemsGlobal Wind Systems

• Prevailing westerliesPrevailing westerlies– Found between 30Found between 30ooN and 60N and 60ooN and 30N and 30ooS S

and 60and 60ooSS– Surface winds move toward the poles in Surface winds move toward the poles in

a westerly direction (again due to the a westerly direction (again due to the Earth’s rotation)Earth’s rotation)

– These move much of the weather across These move much of the weather across the USthe US

Global Wind SystemsGlobal Wind Systems

• Between the polar easterlies and the Between the polar easterlies and the prevailing westerlies lie an area prevailing westerlies lie an area called the called the polar frontpolar front..

• This can bring stormy weather to us.This can bring stormy weather to us.

Global Wind SystemsGlobal Wind Systems

• Trade windsTrade winds are between 30 are between 30ooN and N and 3030ooSS

• These circulation belts move toward These circulation belts move toward the equator in an eastern paththe equator in an eastern path

Jet StreamsJet Streams

• Atmospheric conditions and events Atmospheric conditions and events that happen at the boundaries that happen at the boundaries between wind zones strongly between wind zones strongly influence our weather.influence our weather.

• On either side of the boundaries, On either side of the boundaries, surface air and upper level air differ surface air and upper level air differ in temperature and pressure.in temperature and pressure.

Jet StreamsJet Streams

• The difference in air pressure at the The difference in air pressure at the boundaries causes wind.boundaries causes wind.

• WindWind is the movement of air from an is the movement of air from an area of high pressure to an area of area of high pressure to an area of low pressure.low pressure.

Jet StreamsJet Streams

• A large temperature gradient in A large temperature gradient in upper level air combined with the upper level air combined with the Coriolis effect gives us strong Coriolis effect gives us strong westerly winds called westerly winds called jet streams.jet streams.

• Jet streams are narrow bands of fast Jet streams are narrow bands of fast moving winds.moving winds.

• Its speed varies with the temperature Its speed varies with the temperature differences..differences..

Jet StreamsJet Streams

• The position of the jet stream varies The position of the jet stream varies with the season.with the season.

• Its usually found in the region of Its usually found in the region of strongest temperature differences on strongest temperature differences on a line from the equator to a pole.a line from the equator to a pole.

• It is the strongest core of winds.It is the strongest core of winds.•http://www.youtube.com/watch?v

=CgMWwx7Cll4

Types of Jet StreamsTypes of Jet Streams

• Polar jet streams separate the polar Polar jet streams separate the polar easterlies from prevailing westerlies; easterlies from prevailing westerlies; the major jet streamthe major jet stream

• Weaker jet streams are subtropical Weaker jet streams are subtropical jet streams; found where trade winds jet streams; found where trade winds meet prevailing westerliesmeet prevailing westerlies

• Most storms form along jet streams Most storms form along jet streams and bring large scale weather and bring large scale weather systemssystems

FrontsFronts

• A collision of two air masses is a A collision of two air masses is a front; a narrow region between two front; a narrow region between two air masses of different densitiesair masses of different densities

• Fronts can cover thousands of square Fronts can cover thousands of square milesmiles

Cold FrontsCold Fronts

• Cold front: cold, dense air displaces Cold front: cold, dense air displaces warm airwarm air

• Less dense warm air rises, cools and Less dense warm air rises, cools and condenses: intense precipitation condenses: intense precipitation occursoccurs

• A blue line with evenly spaced blue A blue line with evenly spaced blue triangles is a cold front on a weather triangles is a cold front on a weather mapmap

Warm FrontWarm Front

• Advancing warm air displaces cold Advancing warm air displaces cold airair

• Can cause widespread light Can cause widespread light precipitationprecipitation

• A red line with evenly spaced red A red line with evenly spaced red semicirclessemicircles

Stationary FrontStationary Front

• Two air masses meet but neither Two air masses meet but neither advances; the boundary between advances; the boundary between them stallsthem stalls

• A line of evenly spaced, alternating A line of evenly spaced, alternating cold and warm symbols pointing in cold and warm symbols pointing in opposite directionsopposite directions

Pressure SystemsPressure Systems

• Low PressureLow Pressure– Air from outside replaces rising air, this Air from outside replaces rising air, this

air spirals inward to the center and then air spirals inward to the center and then up in a counter clockwise directionup in a counter clockwise direction

– Rising air cools and condenses into Rising air cools and condenses into clouds and precipitationclouds and precipitation

Pressure SystemsPressure Systems

• High pressure systemsHigh pressure systems– Sinking air moves away from the Sinking air moves away from the

system’s centersystem’s center– Coriolis effect causes sinking air to Coriolis effect causes sinking air to

move to the right, making air circulate move to the right, making air circulate in a clockwise direction in our in a clockwise direction in our hemispherehemisphere

– Fair weatherFair weather

Learning Targets

•Compare and contrast the three major wind systems

• Identify four types of fronts and differentiate between each

Gathering Weather DataGathering Weather Data

• Meteorologists measure atmospheric Meteorologists measure atmospheric conditions such asconditions such as– TemperatureTemperature– Air pressureAir pressure– Wind speedWind speed– Relative humidityRelative humidity

• Two important factors in weather Two important factors in weather forecasting are the accuracy of the data forecasting are the accuracy of the data and the amount of data availableand the amount of data available

Tools for measuring Tools for measuring atmospheric conditionsatmospheric conditions

• A A thermometer thermometer measures measures temperature in F or C.temperature in F or C.

• A A barometerbarometer measures air pressure. measures air pressure.

• An An anemometer anemometer measures wind measures wind speed.speed.

• A A hygrometer hygrometer measures humidity.measures humidity.

ThermometersThermometers• Usually some type of glass tube Usually some type of glass tube

containing a liquid.containing a liquid.

• When heated the liquid expands when When heated the liquid expands when causing the column of liquid to rise.causing the column of liquid to rise.

• When the liquid cools, the column drops.When the liquid cools, the column drops.

BarometerBarometer

• Some have a column of mercury in a Some have a column of mercury in a glass tube.glass tube.

• Changes in air pressure change the Changes in air pressure change the height of the mercury.height of the mercury.

AnemometerAnemometer• The simplest has four The simplest has four

cupped arms cupped arms positioned at right positioned at right angles from each angles from each other.other.

• The arms rotate when The arms rotate when the wind blows.the wind blows.

• The wind’s speed is The wind’s speed is calculated by the calculated by the number of revolutions number of revolutions of the cups over a of the cups over a specific period of timespecific period of time

HygrometerHygrometer• Some have a wet bulb and a Some have a wet bulb and a

dry bulb thermometer and dry bulb thermometer and requires a conversion table requires a conversion table to calculate.to calculate.

• The National Weather The National Weather Service uses an automated Service uses an automated surface observing system to surface observing system to gather data 24 hours a daygather data 24 hours a day

Data From the Upper Data From the Upper AtmosphereAtmosphere

• Weather is largely the result of Weather is largely the result of conditions in the upper atmosphere.conditions in the upper atmosphere.

• An instrument that measures those An instrument that measures those conditions is a radiosonde.conditions is a radiosonde.– Contains a package of sensors Contains a package of sensors

suspended in a balloon that enters the suspended in a balloon that enters the upper atmosphere that collect data upper atmosphere that collect data

Weather RadarWeather Radar

• Radar stands for radio detection and Radar stands for radio detection and rangingranging

• It generates radio waves and It generates radio waves and transmits them through an antenna transmits them through an antenna at the speed of light.at the speed of light.

• The waves reflect when they hit The waves reflect when they hit particles (rain)particles (rain)

Doppler RadarDoppler Radar• Doppler effect is the Doppler effect is the

change in pitch or change in pitch or frequency that occurs frequency that occurs due to the relative due to the relative motion of a waves.motion of a waves.

• Doppler radars measure Doppler radars measure the speed of the speed of precipitation as it moves precipitation as it moves toward and away from toward and away from the radar.the radar.

Weather SatellitesWeather Satellites

• Some satellites move high above the Some satellites move high above the earth using infrared imagery to make earth using infrared imagery to make observations at night.observations at night.

• The imagery can detect differences The imagery can detect differences in frequencies to map cloud cover or in frequencies to map cloud cover or surface temperatures.surface temperatures.

Weather SatellitesWeather Satellites

• Other satellites use visible light to Other satellites use visible light to photograph Earth.photograph Earth.

• These photos are sent back to These photos are sent back to weather stations to analyze cloud weather stations to analyze cloud cover.cover.

Learning Targets

•Discuss the importance of accurate weather data

•Summarize the instruments used to collect weather data from Earth’s surface

•Analyze the strengths and weaknesses of weather radar and weather satellites

Surface Weather AnalysisSurface Weather Analysis

• Weather reports are generated from the Weather reports are generated from the data received from radars and satellites.data received from radars and satellites.

• Station modelsStation models– A record of weather data for a specific spot A record of weather data for a specific spot

at a particular timeat a particular time– Symbols are used to represent the weather Symbols are used to represent the weather

datadata– The symbols allow for the reporting to be The symbols allow for the reporting to be

uniformuniform

Surface Weather AnalysisSurface Weather Analysis

• Plotting station model dataPlotting station model data– To plot data nationally meteorologists To plot data nationally meteorologists

use lines to connect points of equal or use lines to connect points of equal or constant valuesconstant values

– Lines of equal pressure are called Lines of equal pressure are called isobarsisobars

– Lines of equal temperature are called Lines of equal temperature are called isothermsisotherms

Interpreting Station Model Interpreting Station Model DataData

• Using isobars, isotherms, and station Using isobars, isotherms, and station model data, meteorologists can model data, meteorologists can analyze current weather conditions.analyze current weather conditions.

Types of ForecastsTypes of Forecasts

• Digital forecastsDigital forecasts• Created by applying physical properties and Created by applying physical properties and

math to atmospheric variables and then math to atmospheric variables and then making a predictionmaking a prediction

• Analog forecastsAnalog forecasts– Based on comparing current weather Based on comparing current weather

patterns with weather patterns of the patterns with weather patterns of the pastpast

Short Term ForecastsShort Term Forecasts

• The most accurate of all forecasts The most accurate of all forecasts because weather conditions are fluid because weather conditions are fluid and change over timeand change over time

Long Term ForecastsLong Term Forecasts

• Forecasts for months or seasons are Forecasts for months or seasons are based on weather cycles or patterns.based on weather cycles or patterns.

• Forecasts of 5 to 7 days are made Forecasts of 5 to 7 days are made using upper level atmospheric using upper level atmospheric measurements and patterns.measurements and patterns.

Learning Targets

•Analyze a basic surface weather chart

•Distinguish between digital and analog forecasting

•Describe problems with long term forecasts