WeatherWeather

Atmospheric layersAtmospheric layersTroposphere – weather occurs here,

closest to ground, colder as you rise; ends with the tropopause.

Stratosphere – jet stream here; from tropopause up warmer as you rise; ozone

layer is here. Ends with stratopause.

Mesosphere – ice clouds that burn up meteoroids; from stratopause up , colder as

you go up. Ends with mesopause.

Thermosphere – hot layer, made of two layers. Ionosphere where satellites and auroras are; and Exosphere marking the

end of the atmosphere at 800 km.

1.1. Meteorologist – scientists who study the Meteorologist – scientists who study the weather.weather.

What direction do most weather systems What direction do most weather systems travel in the U.S.?travel in the U.S.?

Review 13: WeatherReview 13: Weather

Defining weather…Defining weather… Weather is the daily Weather is the daily

conditions of the conditions of the atmosphereatmosphere

Heat Energy and the AtmosphereHeat Energy and the Atmosphere The Sun’s energy is mostly absorbed by the The Sun’s energy is mostly absorbed by the

Earth but some is reflected back into spaceEarth but some is reflected back into space

The The GreenhouseGreenhouse Effect Effect Caused by the increased amount of CO2 which is Caused by the increased amount of CO2 which is

placed there through burning fossil fuels.placed there through burning fossil fuels.

Krill?, amphipods?Krill?, amphipods?amphipod

copepod

arctic cod

black guillemot

harp seal

ribbon seal

bearded seal

walrus

spotted seal

ringed seal

hooded seal

GREENHOUSE EFFECTGREENHOUSE EFFECT

Air pressureAir pressure Air pressure if the force of air Air pressure if the force of air

pressing down on the Earth’s pressing down on the Earth’s surfacesurface

Highest at sea level.Highest at sea level. As elevation increases (you go up) As elevation increases (you go up)

pressure and density decreases pressure and density decreases (air is thinner).(air is thinner).

Air MassesAir Masses

A large body of air that A large body of air that has properties similar to has properties similar to the part of the Earth’s the part of the Earth’s surface over which it surface over which it develops. develops.

Air Mass MapAir Mass Map

FrontsFronts

A boundary between two air A boundary between two air masses of different density, masses of different density, moisture, or temperature. moisture, or temperature.

Cold FrontCold Front

Warm FrontWarm Front

Occluded FrontOccluded Front

Stationary FrontStationary Front

Severe Weather occurs when Severe Weather occurs when two different fronts collide.two different fronts collide.

Thunderstorms

Lightning

Tornadoes

How do storms begin?How do storms begin?

Types of storms…Types of storms…

Storms –Storms –violent disturbance in the violent disturbance in the atmosphere. Marked by sudden atmosphere. Marked by sudden change in air pressure and rapid air change in air pressure and rapid air movement; two different fronts movement; two different fronts collide (warm meets cold)collide (warm meets cold)

Winter weather…Winter weather…

ThunderstormsThunderstorms Thunderstorms Thunderstorms – cold meets warm – cold meets warm

front.front.

Cyclones and Anticyclones?Cyclones and Anticyclones? CyclonesCyclones – area of low pressure – area of low pressure

that cause rainy stormy weather.that cause rainy stormy weather. AnticyclonesAnticyclones – high pressure area – high pressure area

that causes dry clear fair weather. that causes dry clear fair weather.

Hurricanes and Typhoons are the Hurricanes and Typhoons are the same thing…same thing…

More about tornadoes…More about tornadoes… Great Plains – “tornado alley”.Great Plains – “tornado alley”. Average diameter - .4 kmAverage diameter - .4 km Length traveled – 6 km for only a few Length traveled – 6 km for only a few

minutes but winds can still reach more than minutes but winds can still reach more than 350 km/hour.350 km/hour.

More Severe WeatherMore Severe Weather

Hurricanes Blizzards

Severe Weather SafetySevere Weather Safety

Watches- conditions are favorable Watches- conditions are favorable Warnings- conditions already existWarnings- conditions already exist Examples- Tornadoes, Flooding, Examples- Tornadoes, Flooding,

Thunderstorms, Blizzards, Winter Mixes and Thunderstorms, Blizzards, Winter Mixes and HurricanesHurricanes

Lightning – opposites attract. Lightning – opposites attract. Will strike the tallest positively Will strike the tallest positively

charged object.charged object.

Tornado AlleyTornado Alley

Fujita ScaleFujita Scale

HurricaneHurricane

Saffir-Simson Scale Saffir-Simson Scale measures Hurricanesmeasures Hurricanes

Two sources of Two sources of forecasting weatherforecasting weather– Data collected Data collected

from upper from upper atmosphereatmosphere

– Data collected on Data collected on the Earth’s surfacethe Earth’s surface

Weather Station ModelWeather Station Model

IsobarsIsobars

Isobars-connect points Isobars-connect points of the “same”of the “same”

Examples: Examples: temperature and wind temperature and wind speedspeed

The further away the The further away the lines the lower the lines the lower the wind speedwind speed

WindsWinds Wind is caused by unequal heating of the atmosphereWind is caused by unequal heating of the atmosphere Winds travel from high to low pressureWinds travel from high to low pressure Winds curve to the right in the N hemisphere and to

the left in the S hemisphere called the Coriolis effect

Land and Sea breezesLand and Sea breezes Local winds blow in all directions and in short distances.Local winds blow in all directions and in short distances.

Warm air rises over the land and moves over the water

Cool air sinks and travels toward the land

Cool air sinks toward the land

Warm air rises over the water and moves toward the land

You feel the air moving from water to land during the day

You feel the air moving from land to the water at night

Jet StreamJet Stream jet streamjet stream - strong, - strong,

high speed wind that high speed wind that blows from west to blows from west to east.east.

Located in the Located in the stratosphere.stratosphere.

Moisture in the AirMoisture in the Air

Humidity - Humidity - Water vapor or Water vapor or moisture in the air.moisture in the air.

Dew WaterDew Water – water vapor – water vapor becomes liquid water as it becomes liquid water as it condenses.condenses.

Condensation forms clouds as Condensation forms clouds as water vapor rises and cools.water vapor rises and cools.

MOISTUREMOISTURE

High-pressure system – when cold air sinks to the ground, warms up, and absorbs water vapor, causing sunny skies.

Low-pressure system – when warm air rises higher in the sky, causing water vapor to cool and form clouds and precipitation.

WeatherWeather

Predict what will happen if a high-humidity air mass located over an ocean moves inland and up a mountain slope. Why do you think so?

Movement of Pressure SystemsMovement of Pressure Systems

High Pressure High Pressure moves clockwise moves clockwise and outwardly.and outwardly.

Low Pressure Low Pressure moves moves counterclockwise counterclockwise and inwardly. and inwardly.

CloudsClouds

CirrusCirrus – highest clouds – highest clouds Indicate rain/snow in next 24 hoursIndicate rain/snow in next 24 hours

CumulusCumulus – bright white – bright white wads of cottonwads of cotton

seen with fair weatherseen with fair weather

More on cloudsMore on clouds

CumulonimbusCumulonimbus – largest – largest clouds. Bring heavy rain, high clouds. Bring heavy rain, high

winds, hail and tornadoes.winds, hail and tornadoes.

StratusStratus – form gray sheets – form gray sheets that spread across the skythat spread across the sky

Bring heavy mist, snowBring heavy mist, snow or drizzle. Cause fog.or drizzle. Cause fog.

Describe the clouds you see outside.

Do they fit any of the categories?

Hail – when a raindrop freezes and forms an icy ball before falling to the ground.

Sleet – when a raindrop falls from a cloud and passes through below-freezing air making a slushy blob.

Snow – when ice crystals form in clouds and fall to the ground without melting.

Precipitation typesPrecipitation types

Make a prediction. What kind of precipitation will fall if Make a prediction. What kind of precipitation will fall if there are:there are:

Below-freezing temperatures in the cloudsBelow-freezing temperatures in the cloudsTemp. barely above freezing on the ground?Temp. barely above freezing on the ground?

Describe the Describe the air temperatureair temperature, , precipitationprecipitation, , windswinds, , and and humidity humidity during:during:

Winter?Winter? Spring?Spring?

Summer?Summer? Fall?Fall?

WeatherWeather

Wind speedWind speed is described in miles per hour. is described in miles per hour.

Wind directionWind direction is the direction from which is the direction from which the wind blows.the wind blows.

A north wind comes from the north.A north wind comes from the north.

The tail points to where the wind is coming from. The dot points

to the direction the wind is going.

The barbs on the tail show the speed of the wind. More barbs – faster wind

WeatherWeather

Tools to gather data Tools to gather data about the weather:about the weather:

ThermometerThermometer – measures – measures temperaturetemperature

AnemometerAnemometer – measures – measures wind speedwind speed

Review 13: WeatherReview 13: Weather

Tools to gather data about the Tools to gather data about the weather:weather:

Rain GaugeRain Gauge – measures the – measures the amount of precipitationamount of precipitation

BarometerBarometer – measures air pressure – measures air pressure

Weather VaneWeather Vane – –

indicates wind directionindicates wind direction

Review 13: WeatherReview 13: Weather

Odd-shaped cloudsOdd-shaped clouds

Even more…Even more…

Sun dogsSun dogs

Weather Stations & Weather Map Symbols

Temperature

• Top left number shows the temperature

Weather Symbol

• The symbol between the two numbers on the left indicate what the weather is in terms of precipitation.

• Notice how more symbols indicate intensity

• More snow flake symbols =more snow

• More rain symbols = heavy rain

Dew Point• The number on the

bottom left shows the temperature the air must be for condensation to occur or the Dew Point.

• Humidity is a factor of the dew point.

• This number will be lower than the actual temperature.

• Remember cold air can’t hold moisture like warm air

Cloud Cover The percentage of the circle that is shaded in reflects the percentage of cloud cover in the sky

Similar to a pie chart

Air Pressure • This number is displayed on the top right of the weather symbol

• When the # is high or rising, the weather is fair because the pressure is high

• When the # is low or dropping, the weather is rainy, because the pressure is low

Wind Barb• This shows the

direction of the wind, it will point in the direction the wind is coming from, this shows the wind coming from the Southeast

• The # of lines and/or triangles indicates the speed of the wind

• The wind barb points in the direction it is coming FROM.• Stronger winds have more flags, or marks

Fronts on a weather mapWarm occluded

• Cold

Stationary

The symbols point in the directiondirection that the front is moving towards

Pressure symbols:

Isobars: connect areas with equal air pressureThe distance between the isobars is called the

pressure gradient • The closer the isobar lines, the greater the change in air pressure, and the greater/faster the winds speeds.

• High pressure systems bring clear/sunny weather and wind flows out and clockwise (right)

• Low pressure systems bring overcast/stormy weather and wind flows in and counter-clockwise (left)