Download Wind and Weather Patterns

Chapter 2 Lesson 2.1
Wind
and
Weather Patterns
T.O.C:
The Atmosphere’s Air Pressure Changes
Air Exerts Pressure
 Air molecules move constantly. As they move they
bounce off one another & every surface they hit.
 Each time air molecules bounce off an object, it
pushes, or exerts force, on the object
 Air Pressure-w.w- force of air molecules pushing on
an area. (14.7 lbs of air pressure)
 The greater the force = higher air pressure
 B/c air molecules move in all directions→ air pressure
pushes in all directions
 Air pressure is related to altitude & density. Air
pushing down is same as air pushing up from below.
Pressure & Air Motion
 Air pressure decreases as you move higher in the
atmosphere.
 Density of air also decreases → b/c air molecules are
closer together when closer to the surface of Earth &
further apart w/ higher altitude.
 Air pressure can also vary in 2 locations of the same
altitude. (Ex: opening a can of soda)
 If air pressure were the same at all locations, air
wouldn’t move much. B/c of differences in pressure,
air starts to move from areas of high pressure toward
areas of low pressure.
 Air may move only a short distance, or travel for miles.
 Balloon & Egg/Bottle Demo
Barometers & Air
Barometer-w.w- anyPressure
instrument that measures air pressure.
Galileo temperature gauge
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 LAB
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Build your own Barometer!
Labs/Activities Section: Barometer & Air Pressure
Materials Needed: scissors, balloon, metal can, rubber band, thin
straw, tape, ruler
In your Notebook, create a graph to track changes in air pressure
over the next week or so.
 How to Build It:
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Cut open balloon along one side until you get close to the end.
Stretch balloon across top of can & secure with rubber band.
Cut thin straw at angle on one end to create a pointer. Tape the
other end of the straw to the center of the balloon. Tape a ruler
against a box or the wall & position the can so that the pointer
almost touches the ruler.
Record the position of the pointer.
Record for the following week & compare to local weather readings
2.1 Review Q’s 13 pts
1. How does the number of air molecules relate to air
pressure? (2 pts)
2. How does the movement of air molecules cause
pressure? (2 pts)
3. How does altitude affect air pressure? (2 pts)
4. How does air density relate to air pressure?
(2 pts)
5. Explain how differences in air pressure affect the
movement of air? (2 pts)
6. Would you expect the air pressure in a valley below
sea level to be higher or lower than air pressure at
sea level. Explain. (3 pts)
Chapter 2
Lesson 2.2
T.O.C:
The Atmosphere Has Wind Patterns
Uneven Heating Causes Air to
Move
 Weather-w.w- condition of Earth’s atmosphere
at a particular time & place.
 Wind is an important part of weather.
 Wind-w.w- air that moves horizontally, or
parallel to the ground. Carries & produces storms.
 Remember: air pressure differs from place to place at
the same altitude.
 Uneven heating of Earth’s surface causes such
pressure differences→ this sets air into motion.
 Short distances- Wind moves from high pressure
areas to low pressure.
Air = Wind
Convection of air mvmt. Create Illustration.
1.
Sunlight heats area of ground → ground heats air →
warm air rises → area of low pressure forms.
2. Sunlight heats area of ground less strongly → cooler,
denser air sinks slowly → area of high pressure forms
3. Air moves as wind across the surface from high pressure
area to low pressure areas.
• When the difference in pressure between 2 areas is
small, the wind may move too slow to be noticed.
• A very large difference in pressure can produce winds
strong enough to uproot trees.
Air = Wind
 Remember: Some winds travel far, some die out
quickly
 Global Winds- w.w- travel 1,000’s of miles in
steady patterns & lasts for weeks.
 Caused by uneven heating between the equator & the
N/S poles.
 Sunlight at equator is more concentrated due to
angle of Earth. So, the surface (land/water) heats the
surface to a high temp creating low pressure areas.
 Sunlight at poles is less concentrated (spread out)
also due to angle of Earth. So, the air is cooler and
more dense.
 Thus→ Global Winds are created! Mwahahaha!!!
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Earth’s Rotation Affects Wind
Direction
If Earth didn’t rotate,
global winds would flow
directly from the poles to the equator.
 However, Earth’s rotation changes the direction
of winds & other objects moving over Earth.
 Coriolis Effect-w.w- Influence of Earth’s rotation
 Only noticeable for winds that travel long distances
 Global winds curve as Earth turns beneath them.
 N. Hemi= winds curve to the right
 S. Hemi= winds curve to the left
 Balloon Demo!!
 Global winds travel along 3 different routes in
each hemisphere. Called global wind belts.
About Global Wind Belts
 The wind belts created by Earth’s uneven heating & rotation are
separated by calm regions. Each calm region is an area of high
or low pressure.
 Calm Regions: winds are light & often change direction
 Doldrums: low pressure zone near equator. The rising, moist
air produces clouds & heavy rain.
 The horse latitudes: high pressure zones located about 30
degrees N/S of the equator. Weather tends to be dry & clear
 The 3 Global Wind Belts:
 The Trade Winds: blow from the East. Move from horse
latitudes toward equator. Strong, steady die out near
equator.
 The Westerlies: blow from the West. Move from horse
latitudes toward the poles. Bring storms across much of U.S.
 The Easterlies: blow from the East. Move from polar regions
downward. Stormy weather often occurs as this cold air
meets the warm air of the Westerlies.
About Jet Streams
 Not all long-distance winds travel along Earth’s surface.
 Jet Stream-w.w- usually flow in the upper troposphere
from W to E for 1,000’s of miles.
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Air in jet streams often move at speeds greater than 125 mph
Also form b/c of Earth’s uneven heating
Loop N & S
Each hemisphere usually has 2 jet streams: A polar jet stream &
a subtropical jet stream.
Affect weather (polar jet stream in N Hemi affects weather in
U.S. & Canada
Can affect air travel b/c this is where most planes fly. Flight
times can be shortened or lengthened
Local Winds & Monsoons!
 Patterns of heating & cooling in the air cause local winds &
even monsoons!
 Local Winds: Sea breezes & land breezes occur near
shorelines. During day→ land heats up faster than water so
the air over the land rises & expands → dense air from water
moves in to take its place causing a sea breeze. During
night→ The pattern is reversed → water finally getting warm
causes air over water to rise & expand→ air over land is cool
now→ land air moves in over ocean creating land breeze.
(valley/mtn breezes caused like this too)
 Monsoon-w.w- winds that change direction w/ the seasons.
Created the same way as local winds but travel over & affect
much larger (huge) areas. Think African savannahs…
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Causes rainy seasons in summer when moist air flows inland
from the sea as land heats up & dry seasons in winter when the
lands cools off & the winds flow back out to sea.
https://www.youtube.com/watch?v=g4O9z_R5ZSc&list=PLCE7EE0E60A4CB6B1
2.2 Review Q’s 27 points
1. How does the uneven heating of Earth’s surface cause winds
to flow? What is this process called? (3 pts)
2. How does Earth’s rotation influence the movement of global
winds? Explain this effect for both hemispheres. (4 pts)
3. How do monsoons affect rainfall? (2 pts)
4. Why do some winds change direction in areas where land is
near water, especially from day to night? (2 pts)
5. What factor determines the strength of wind speed? (2 pts)
6. What are the 2 calm regions that separate the global wind
belts? Give their location. (4 pts)
7. What directions do the 3 global wind belts & the jet stream
flow? (8 pts)
8. What is a barometer? How is the Galileo thermometer like a
barometer? (2 pts)
Chapter 2
Lesson 2.3
T.O.C.
Clouds & the Water Cycle
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Most Clouds Form as Air Rises &
Temperature affects water inCools
the air. When temperature changes→ water
changes form. Water cycle is part of cloud development.
Forms of Water in Atmosphere
Evaporation-w.w- liquid water changes into gas. For water to evaporate
it needs extra energy
Condensation-w.w- when gas (water vapor) changes back into a
solid/liquid; like tiny crystals & water droplets. Occurs when moist air
cools. This is when clouds form (on something solid)
Precipitation-w.w- any type of liquid or solid water that falls to Earth’s
surface.
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Types of Precipitation
Rain/Drizzle- form from liquid droplets or ice crystals
Freezing rain- raindrops that freeze when they hit ground
Sleet- small pellets of ice
Snow- ice crystals grow & merge in clouds & become unique snowflakes→
all are different! Like fingerprints!
Hail- lumps or balls of ice that fall from cumulonimbus clouds. Usually see
hail before tornadoes.
Acid rain- rain that is more acidic than normal due to pollution
Water Cycle Demo
Humidity & Saturation
 Humidity-w.w- amount of water vapor in the air. Varies from
place to place & time to time. Eventually air reaches:
 Saturation-w.w- condition in which the rates of evap. &
cond. are equal.
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Amt of water vapor in air at saturation depends on temperature; the
warmer the air- the more water it takes to saturate it
Humidity of Air in 2 Different Ways
 Relative humidity-w.w- compares amt of water vapor in air
w/ maximum amount of water vapor that can be present at
that temp.
Ex: air w/ 50% R.H. has ½ the amt of water needed for
saturation.
 Dew point-w.w- temp at which air w/ given amt of water
vapor will reach saturation. Ex: air w/ dew point of 79°F will
become saturated if it cools to 79°F. The higher the dew point
→ the more water vapor in the air!
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Water Vapor Condenses to Form
Clouds
When water vapor rises to the point that it begins to
cool it will begin to condense.
 Water vapor needs something solid to condense on.
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Ex: on land→ water condenses on grass
Ex: in air → water condenses on tiny particles such as dust,
smoke, & salt from oceans
Cloud in a Jar – class experiment
Labs/Activities Section- Cloud in a Jar
Materials:
Glass jar, hot water, plate/bowl, ice, match (see me)
Answer:
Why was the match needed?
How did the lab show condensation & cloud creation?
Kinds of Clouds
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Anyone who has spent time looking at clouds knows that clouds
don’t look alike. But why?
Clouds have different characteristics b/c they form under different
conditions.
Clouds are classified & named according to
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Altitude- high altitude= clouds form out of ice crystals; low altitude=
clouds are made of water droplets or mix of droplets & ice crystals.
The way they form by air mvmt
General characteristics (the way they look)
Shapes & sizes of clouds are mainly determined by air mvmt.
 Ex: Fluffy clouds form where air rises sharply or moves straight
up & down (↓↑)
 Ex: Flat, smooth clouds covering large areas form where air
rises gradually.
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Meanings of Cloud Names→ create Illustration
3 Main Types of Clouds
Cirrus-w.w- form in high altitude (upper troposphere), means “curls of hair” &
appear wispy/feathery. Made of ice crystals & strong winds leaving “tails”.
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Cumulus-w.w- form from low to high, can be very tall. Means “heap” or “pile”
b/c looks like cottonballs stacked & fluffy in the sky.
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Usually appear during the day in good weather when warm air rises
If they grow tall enough the can produce precipitation. Cumulonimbus clouds are
thunderheads that produce heavy rainfall. Top often juts out sharply.
Stratus-w.w- means “spread out” form in flat layers low in the atmosphere, one
on top of another, when air cools over a large area w/out rising or rises slightly.
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Can be seen in good weather & sometimes before a storm.
Can make the whole sky look grey
Smooth b/c they form w/out strong air mvmt
Low nimbostratus clouds can be so dark to block out the sun & produce steady,
light precipitation
“Nimbo/nimbus”- clouds with precipitation
“Alto”- clouds at medium altitude.
Fog-w.w- cloud that rests on the ground or a body of water.
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Usually forms when a surface is colder than the air above it. Water vapor in the air
condenses as it cools, forming a thick mist. Usually forms at dawn.
Cumulus
Fog
Stratus
Cirrus
Cumulus
Cumulus
Stratus
Cumulonimb
us
Nimbostratu
Fog
With a partner,
try to
s
Cumulonimb
identify
the
following
Stratus
us
w/
cloud
types!
Make sure
Cirrus
Tornado
both names
are on the
2.3 Review Q’s 35 points
1. What is humidity? What 2 ways describe humidity? (3 pts)
2. What is saturation? (2 pts)
3. Describe the 3 forms water takes in the atmosphere. (think
water cycle) (6 pts)
4. How are clouds classified? (3 pts)
5. If a cloud type has the word “nimbo/nimbus” in it what does
that imply? If a cloud has the word “alto” in it what is it
implying? (2 pts)
6. What are the 3 main types of clouds? Describe each one. (6 pts)
7. How does fog form? (2 pts)
8. What does water need to be able to condense? Give an
example. (2 pts)
9. Name 4 forms of precipitation. (4 pts)
10. Describe each of the following cloud types: cirrostratus;
cumulonimbus, cirrocumulus, altostratus, nimbostratus. (5 pts)