Chapter 2 – Weather PatternsChapter 2 – Weather PatternsGuided NotesGuided Notes

Objective(s)Objective(s)::7.E.1.4 7.E.1.4

Predict weather conditions and patterns based Predict weather conditions and patterns based on information obtained from:on information obtained from:

• Weather data collected from direct observations and measurement (wind speed and direction, air temperature, humidity and air pressure)• Weather maps, satellites and radar• Cloud shapes and types and associated elevation

7.E.1.5 Explain the influence of convection, global winds and the jet stream on weather and

climatic conditions.

• Learner Objective(s):Learner Objective(s):

Students will understand that the Students will understand that the water cycle and atmospheric water cycle and atmospheric conditions are interconnected and conditions are interconnected and create the weather we see on Earth.create the weather we see on Earth.

Concept/Vocabulary Word Concept/Vocabulary Word Definition Definition • DepositionDeposition - The process of water vapor changing from - The process of water vapor changing from

a gas directly into a solid.a gas directly into a solid.• Dew PointDew Point - The temperature at which water vapor will - The temperature at which water vapor will

start to condense out of the air as liquid water. start to condense out of the air as liquid water. • EvaporationEvaporation - The process of a liquid changing into a - The process of a liquid changing into a

gasgas• FogFog - Clouds that form at the surface of the Earth. - Clouds that form at the surface of the Earth.• Ground WaterGround Water - Water that has infiltrated (sunk) into - Water that has infiltrated (sunk) into

the ground.the ground.• HydrosphereHydrosphere - All of the Earth's water that is cycling - All of the Earth's water that is cycling

within the water cycle.within the water cycle.• MeteorologistMeteorologist - A scientist who studies the - A scientist who studies the

atmosphere, weather and climateatmosphere, weather and climate• PrecipitationPrecipitation - Any type of liquid or solid water that - Any type of liquid or solid water that

falls to Earth's surface.falls to Earth's surface.  

• Run Off Run Off - Water that flows across the surface of - Water that flows across the surface of the Earth.the Earth.

• SublimationSublimation - The process of water changing - The process of water changing from a solid directly into a gas.from a solid directly into a gas.

• TranspirationTranspiration - The process of water - The process of water evaporating from the leaves of plants during evaporating from the leaves of plants during photosynthesis.photosynthesis.

• Water CycleWater Cycle - The repeating processes that - The repeating processes that move water in different forms between Earth's move water in different forms between Earth's surface and the atmospheresurface and the atmosphere

• Water vaporWater vapor - Water in the atmosphere that is - Water in the atmosphere that is in the form of a gas.in the form of a gas.

• WeatherWeather - The condition of Earth's atmosphere - The condition of Earth's atmosphere at a particular time and placeat a particular time and place

• Weather patternsWeather patterns - Weather that repeats itself - Weather that repeats itself in a predictable way. in a predictable way.

I.I. SECTION 2.1 – The atmosphere’s SECTION 2.1 – The atmosphere’s air pressure changesair pressure changesA.A. Air exerts pressureAir exerts pressure

• Exploring air pressure – What does air do to the egg? Exploring air pressure – What does air do to the egg?

http://www.youtube.com/watch?v=2VHneRg0mhI&list=PLMWvLl-qJ8maQ15p1kZBooG1L1AoFCz6_&feature=plcp

• Air Air pushespushes or exerts a or exerts a forceforce• Air pressure – Air pressure – is the force of air molecules pushing on an areais the force of air molecules pushing on an area• As you move As you move upwardupward in the atmosphere, air pressure in the atmosphere, air pressure decreasesdecreases• The greater the The greater the forceforce, the higher the , the higher the air pressureair pressure• Air pressure pushes in Air pressure pushes in allall directions directions  

B.B. Pressure and Air motionPressure and Air motion• Air pressure Air pressure decreasesdecreases as you move to as you move to higherhigher altitude altitude

• Air moves from areas of Air moves from areas of higher pressurehigher pressure to areas of to areas of lower lower pressurepressure

C. Barometers and Air PressureBarometer – is any instrument that measures air pressure

III. III. SECTION 2.2SECTION 2.2. . – The – The atmosphere has wind atmosphere has wind patternspatterns• Wind blows from areas of Wind blows from areas of

high pressure toward areas of low high pressure toward areas of low pressure. Earth's rotation causes pressure. Earth's rotation causes long distance winds to curve.long distance winds to curve.

area of high

pressure

area of low pressure

A.A. Uneven heating causes air to moveUneven heating causes air to move

•Weather – Weather – is the condition of Earth’s is the condition of Earth’s atmosphere at a particular time and placeatmosphere at a particular time and place

•Wind – Wind – is air that moves horizontally, or is air that moves horizontally, or parallel to the groundparallel to the ground

•Uneven heating causes Uneven heating causes pressure differencespressure differences which set air in motionwhich set air in motion

•Over a short distance, wind moves directly Over a short distance, wind moves directly from higher pressure toward lower pressurefrom higher pressure toward lower pressure

•Global winds - Global winds - travel thousands of kilometers travel thousands of kilometers in steady patterns and last for weeksin steady patterns and last for weeks

•Uneven heating between the Uneven heating between the equatorequator and the and the northnorth and and southsouth poles cause global winds poles cause global winds

B.B. Earth’s rotation affects wind directionEarth’s rotation affects wind direction

•Coriolis effect – Coriolis effect – influence on Earth’s rotationinfluence on Earth’s rotation•Global windsGlobal winds curve as Earth turns beneath curve as Earth turns beneath

themthem• In the In the NorthernNorthern Hemisphere, winds curve to Hemisphere, winds curve to

the right in the direction of motionthe right in the direction of motion• In the In the SouthernSouthern Hemisphere, winds curve to Hemisphere, winds curve to

the left in the direction of motionthe left in the direction of motion• The Coriolis effect is noticeable only The Coriolis effect is noticeable only

for winds that travel for winds that travel longlong distances distances http://www.youtube.com/watch?v=uBqohRu2RRk&list=PLMWvLl-qJ8maUvrKjCzRx27pJ9NnKCcWG&feature=mh_lolz

• Investigate: How does Earth’s rotation affect wind?  Investigate: How does Earth’s rotation affect wind?  C.C. Bands of calm air separate global wind Bands of calm air separate global wind

beltsbelts•Calm regions – Calm regions – doldrums and horse latitudesdoldrums and horse latitudes

– Doldrums – Doldrums – are a low-pressure zone near the equatorare a low-pressure zone near the equator– Horse latitudes – Horse latitudes – are high-pressure zones located about 30 are high-pressure zones located about 30

degrees north and 30 degrees south of the equator degrees north and 30 degrees south of the equator •Wind belts – Wind belts – trade winds, westerlies, and easterlies trade winds, westerlies, and easterlies

– Trade winds – Trade winds – blow from east, moving from the horse blow from east, moving from the horse latitudes toward the equatorlatitudes toward the equator

– Westerlies – Westerlies – blow from the west, moving from the horse blow from the west, moving from the horse latitudes toward the equator. They bring storms across latitudes toward the equator. They bring storms across much of the United Statesmuch of the United States

– Easterlies – Easterlies – blow from the east, moving from the polar blow from the east, moving from the polar regions toward the mid-latitudes. Stormy weather often regions toward the mid-latitudes. Stormy weather often occurs when the cold air of the easterlies meet the warmer occurs when the cold air of the easterlies meet the warmer air of the westerliesair of the westerlies

http://www.youtube.com/watch?v=I0C4QR0OEH0&list=PLMWvLl-qJ8mY36sh_gV7Ume-7kIPbtYIF&index=1&feature=plpp_video

D.D.Jet streams flow near the top of the Jet streams flow near the top of the tropospheretroposphere• Jet Streams – Jet Streams – usually flow in the usually flow in the

upper troposphere from west to upper troposphere from west to east for thousands of kilometerseast for thousands of kilometers

• Air often moves at speeds greater Air often moves at speeds greater than than 200 km/hr or 124 mph200 km/hr or 124 mph

• Forms when earth’s surface is Forms when earth’s surface is heated unevenlyheated unevenly

• Loop north and southLoop north and south• Each hemisphere usually has two Each hemisphere usually has two

jet streamsjet streams

E.E. Patterns of heating and cooling Patterns of heating and cooling cause local winds and monsoonscause local winds and monsoons•Local winds – Local winds – sea breezes and land breezessea breezes and land breezes

– Occur near shorelinesOccur near shorelines

Valley breezes

•Monsoons – Monsoons – winds that change directions winds that change directions with the seasonswith the seasons

– Caused by the different heating and cooling rates Caused by the different heating and cooling rates of land and seaof land and sea

III.III. SECTION 2.3 – Most clouds SECTION 2.3 – Most clouds form as air rises and coolsform as air rises and cools

A.A. Temperature affects water in the airTemperature affects water in the air• Water is Water is always in the atmospherealways in the atmosphere• Evaporation – Evaporation – is the process by which a liquid changes is the process by which a liquid changes

into a gas. For water to evaporate, it needs extra energy.into a gas. For water to evaporate, it needs extra energy.http://techalive.mtu.edu/meec/module01/EvaporationandTranspiration.htm* Condensation – is the process by which gas, such as water vapor, changes into a liquid. Condensation occurs when moist air cools.

B. Water in the Air • Precipitation – any type of liquid or solid water that falls to Earth’s surface

C.C. Humidity and Relative HumidityHumidity and Relative Humidity•Humidity – Humidity – is the amount of water vapor in the is the amount of water vapor in the

airair•Saturation – Saturation – a condition in which the rates of a condition in which the rates of

evaporation and condensation are equalevaporation and condensation are equal•Unsaturated Air – Unsaturated Air – more water evaporates into more water evaporates into

the air than condenses back into the waterthe air than condenses back into the water•Saturated Air – Saturated Air – the amount of water that the amount of water that

evaporates equals the amount that condensesevaporates equals the amount that condenses

• Relative humidity – Relative humidity – compares the amount of water compares the amount of water vapor in air with the maximum amount of water vapor in air with the maximum amount of water vapor that can be present at that temperaturevapor that can be present at that temperature– Air with 50% relative humidity has ½ the Air with 50% relative humidity has ½ the

amount of water needed for saturation. If the amount of water needed for saturation. If the amount of water vapor in air stays the same, amount of water vapor in air stays the same, relative humidity will decrease as the air heats relative humidity will decrease as the air heats up and increase as the air cools up and increase as the air cools

• Dew point – Dew point – is the temperature at which air with a is the temperature at which air with a given amount of water vapor will reach saturationgiven amount of water vapor will reach saturation– Air with a dew point of 26 degrees C (79 F) will Air with a dew point of 26 degrees C (79 F) will

become saturated if it cools to 26 degrees Cbecome saturated if it cools to 26 degrees C

D.D. Water vapor condenses and forms cloudsWater vapor condenses and forms clouds• Clouds are made of Clouds are made of condensed water vaporcondensed water vapor• Rising warm air can produce clouds. Water vapor begins Rising warm air can produce clouds. Water vapor begins

to condense when the air cools to its dew point. to condense when the air cools to its dew point. • Investigate – How does a cloud form? Pg. 59Investigate – How does a cloud form? Pg. 59

E.E. Characteristics of CloudsCharacteristics of Clouds• The shape and size of clouds are determined by The shape and size of clouds are determined by air air

movementmovement• Names of clouds that produce Names of clouds that produce precipitationprecipitation contain contain

the word part the word part nimbo-nimbo- or or nimbusnimbus• Names of clouds that form at a Names of clouds that form at a mediummedium altitude altitude

have the prefix have the prefix alto-alto-

Clouds are made of tiny water droplets that condense from water vapor in rising air.level where

condensation begins

• Cirrus Clouds – Cirrus Clouds – means “curl of hair.” Cirrus clouds means “curl of hair.” Cirrus clouds appear feathery or wispyappear feathery or wispy– Form in very cold air in high altitudesForm in very cold air in high altitudes– Made of ice crystalsMade of ice crystals– Usually found in fair weatherUsually found in fair weather– They can be a sign that a storm is approachingThey can be a sign that a storm is approaching

• Cumulus Clouds – Cumulus Clouds – means “heap” or “pile.” means “heap” or “pile.” Cumulus type clouds can grow to be very tallCumulus type clouds can grow to be very tall– Puffy white clouds with darker basesPuffy white clouds with darker bases– Looks like cotton balls floating in the skyLooks like cotton balls floating in the sky– Usually appear in daytime in fair weather, when Usually appear in daytime in fair weather, when

warm air rises and its water vapor condenses. warm air rises and its water vapor condenses. Cooler air sinks along the sides of the clouds, Cooler air sinks along the sides of the clouds, keeping them separate from each otherkeeping them separate from each other

• Stratus Clouds – Stratus Clouds – means “spread out.” Stratus type clouds form means “spread out.” Stratus type clouds form in flat layersin flat layers– Form in layers when air cools over a large area without rising Form in layers when air cools over a large area without rising

or when the air is gently liftedor when the air is gently lifted– Are smooth because they form without strong air movementAre smooth because they form without strong air movement– Low stratus clouds are so dark that they completely block out Low stratus clouds are so dark that they completely block out

the sun. These clouds produce steady, light precipitationthe sun. These clouds produce steady, light precipitation– Ones that form at high altitudes are much thinner than low Ones that form at high altitudes are much thinner than low

lying ones – you can see the sun and moon through themlying ones – you can see the sun and moon through them– Ice crystals in high clouds can make it seem as if there’s a Ice crystals in high clouds can make it seem as if there’s a

circle of colored light around the sun or the mooncircle of colored light around the sun or the moon

• Fog – Fog – is a cloud that rests on the ground or a body of wateris a cloud that rests on the ground or a body of water– Has a smooth appearanceHas a smooth appearance– Usually forms when a surface is colder than the air above it Usually forms when a surface is colder than the air above it – Water vapor in the air condenses as it cools forming a thick Water vapor in the air condenses as it cools forming a thick

mistmist– On land it tends to be heaviest at dawn, after the ground On land it tends to be heaviest at dawn, after the ground

has cooled overnight. It clears as the ground is heated by has cooled overnight. It clears as the ground is heated by the sunlightthe sunlight

– Often makes transportation dangerous by limiting visibilityOften makes transportation dangerous by limiting visibility– In the US, about 700 people die each year in automobile In the US, about 700 people die each year in automobile

accidents that occur in dense fogaccidents that occur in dense fog

• 10 total clouds:10 total clouds:– CirrusCirrus– CirrocumulusCirrocumulus

• CirrostratusCirrostratus

– AltocumulusAltocumulus

• CumulonimbusCumulonimbus

• AltostratusAltostratus

• NimbostratusNimbostratus

• Cumulus• Stratus

IV.IV. SECTION 2.4 – Water falls to SECTION 2.4 – Water falls to Earth’s surface as precipitationEarth’s surface as precipitation

A.A. Precipitation forms from water droplets or ice Precipitation forms from water droplets or ice crystalscrystals

• All precipitation comes from All precipitation comes from cloudsclouds• Cloud droplets are held in the air by Cloud droplets are held in the air by slight slight

upward movement of air upward movement of air • When cloud droplets combine, they form When cloud droplets combine, they form rain rain

(precipitation)(precipitation)

• It takes about It takes about a milliona million droplets to make a single droplets to make a single raindropraindrop

• When the temp is below freezing, water vapor When the temp is below freezing, water vapor turns turns into tiny ice crystals into tiny ice crystals

• Crystals grow by Crystals grow by collecting more water vaporcollecting more water vapor or or by by colliding and mergingcolliding and merging with one another with one another

• Most rain in the US starts out as Most rain in the US starts out as falling ice falling ice crystalscrystals, however, before they can reach the , however, before they can reach the ground ground they meltthey melt in a layer of warm air in a layer of warm air

'Dro' and the Weather Map'Dro' and the Weather Map More About RaindropsMore About Raindrops

Here are a few of my raindrop mates! ...

This is 'Megadrop'.It is a large raindrop.

It is 5 millimeters in size.As it falls from the sky it flattens out.

This is 'Dropoid'.It is a small raindrop.

It is only 1 millimeter in size.

Cloud droplets are so small that you need a magnifying glass to see them.

Most people think thatraindrops look like tear drops.

Like the one below.

This is not true. They are round like me or a little flatter like 'Megadrop'.

B.B. Measuring PrecipitationMeasuring Precipitation•Scientists uses a Scientists uses a rain gaugerain gauge to measure rainfall to measure rainfall•Snow depthSnow depth can be measured with a long ruler can be measured with a long ruler

• Types of PrecipitationWater droplets in clouds merge to form raindrops.

Ice crystals in clouds can form snow, rain, and other types of precipitation.

Hail forms when ice pellets move up and down in clouds, growing larger as they gain layers of ice.

Snow forms from ice crystals that merge in clouds.

Sleet is rain that freezes into ice pellets while falling through cold air.

Freezing rain is rain that freezes when it hits the ground or other surfaces.

•Rain and DrizzleRain and Drizzle– Most common type of precipitationMost common type of precipitation– Raindrops form from liquid cloud droplets or from ice Raindrops form from liquid cloud droplets or from ice

crystals that melt as they fall crystals that melt as they fall – A light rain with very small drops is called drizzleA light rain with very small drops is called drizzle– Drizzle usually comes from stratus clouds, which don’t Drizzle usually comes from stratus clouds, which don’t

have enough air movement to build up larger have enough air movement to build up larger raindropsraindrops

•Freezing Rain AKA IceFreezing Rain AKA Ice– Rain that freezes when it hits the ground or other Rain that freezes when it hits the ground or other

surfaces in cold weathersurfaces in cold weather– Covers surfaces with a coating of iceCovers surfaces with a coating of ice– Can make roads slippery and dangerousCan make roads slippery and dangerous– Weight of the ice can bring down trees and power linesWeight of the ice can bring down trees and power lines

•SleetSleet– Rain that freezes before it hits the groundRain that freezes before it hits the ground– Are small pellets of ice Are small pellets of ice

•SnowSnow Ice crystals that grow and merge in clouds become snowflakesSnowflakes come in different shapes and sizes but usually has 6 sides or branchesWhen snow falls through moist air that is near freezing, flakes tend to join together in clumpsWhen snow falls through colder and drier air, snowflakes don’t join together and snow is powdery

•HailHail– Largest type of frozen precipitationLargest type of frozen precipitation– Arrives in warm weatherArrives in warm weather– Are lumps or balls of ice that fall from cumulonimbus Are lumps or balls of ice that fall from cumulonimbus

cloudsclouds– During a thunderstorm, violent air currents hurl ice During a thunderstorm, violent air currents hurl ice

pellets around the cloudpellets around the cloud– Pellets grow as water droplets freeze onto them at Pellets grow as water droplets freeze onto them at

high elevations. Some start to fall but are pushed high elevations. Some start to fall but are pushed back up again. This may repeat several times adding back up again. This may repeat several times adding a layer of ice each time. Eventually they fall to the a layer of ice each time. Eventually they fall to the ground.ground.

– Largest hailstone weighed 1.7 pounds and was as Largest hailstone weighed 1.7 pounds and was as wide as a CDwide as a CD

– Precipitation can carry pollutionPrecipitation can carry pollution•Rainwater is naturally a little acidicRainwater is naturally a little acidic•Acid rain – Acid rain – is rain that has become much more is rain that has become much more

acidic than normal because of pollutionacidic than normal because of pollution•Factories, power plants, automobiles, and some Factories, power plants, automobiles, and some

natural sources release sulfur dioxide and natural sources release sulfur dioxide and nitrogen oxides into the air. Theses gases nitrogen oxides into the air. Theses gases combine with water vapor to form sulfuric acid combine with water vapor to form sulfuric acid and nitric acid. The acids mix with cloud and nitric acid. The acids mix with cloud droplets or ice crystals and falls to the surface droplets or ice crystals and falls to the surface as precipitation.as precipitation.

•Acid rain harms Acid rain harms treestrees and raises the and raises the acidityacidity of of lakes, making it difficult for fish to live in themlakes, making it difficult for fish to live in them

•Acid rain also damages the surfaces of Acid rain also damages the surfaces of buildingbuilding and and sculpturessculptures