Download Wind and Weather

Wind and Weather Notes
8th Grade Science
Mrs. Melka 2016-17
https://www.youtube.com/watch?v=KQuVOQwRvQ8
Why is Wind Important? – Part 1
• Because wind systems determine
major weather patterns on Earth.
• Wind also helps determine where
planes and ships travel most efficiently.
How Wind Moves #1: Convection
• Uneven heating of Earth by the Sun
causes some areas to be warmer than others
• Warm air rises = molecules are spread out;
is less dense; has lower pressure
• Cold air sinks = molecules are closer
together; is more dense; has higher
pressure
• Cooler air displaces the warmer air causing
convection currents
(remember the lava lamp!)
How Wind Moves #2: Coriolis Effect
• The winds curve because of Earth’s
rotation on its axis
• Hot air near the equator rises & moves
toward poles
• Cool air near the poles falls & moves
toward equator
• Their paths are curved because of the
Coriolis Effect
– Northern Hemisphere = curves right
– Southern Hemisphere = curves left
Global/Prevailing Winds
“The term horse
latitudes supposedly
originates from the days
when Spanish sailing
vessels transported
horses to the West
Indies. Ships would
often become becalmed
in mid-ocean in this
latitude, thus severely
prolonging the voyage;
the resulting water
shortages would make it
necessary for crews to
throw their horses
overboard.”
Global/Prevailing Winds
• Westerlies:
– Found between 30o & 60o north & south latitudes
– Blow from the west (from west to east)
– Move weather systems in the US from west to east
• Doldrums:
– Nearly windless, rainy zone found along equator
• Trade Winds:
– Air sinking near 30o north & south latitudes
– Creates steady wind that blows from the east
– Called trade winds because early sailors used their
dependability to establish trade routes
Global/Prevailing Winds
• Polar Easterlies:
– Found near poles
– Blow from the east (from east to west)
• Jet Streams:
– Narrow belts of strong winds in the upper atmosphere
– In US moves from west to east
– Planes = if flying eastward, pilots use jet stream to
save time and fuel; if flying westward, pilots fly at
different altitudes to avoid jet stream
Global/Prevailing Winds
• Jet Streams:
Weather
• Weather:
– Condition of atmosphere at specific time and
place
– Occurs as result of Sun’s heat energy and
Earth’s air and water interacting
Weather
Weather Factors:
• Air Temperature
• Wind
• Humidity
Weather
Air Temperature:
– Measure of average amount of motion of
molecules
– Low Temperature = molecules move slower
– High Temperature = molecules move faster
Weather
Wind:
• Wind is caused by air put into motion by the energy
from the Sun.
– Warm air = less dense & lower pressure (RISES)
– Cold air = more dense & higher pressure
(SINKS)
– Wind results because HIGH pressure air (cold
air) moves toward LOW pressure air (warm air)
and replaces it (the warm air moves up and cold
air takes its place)
– Wind moves weather systems around Earth.
https://www.youtube.com/watch?v=uBqohRu2RRk
Weather
Interesting Wind Facts:
The highest wind
speed ever
recorded on the
surface of the Earth
was 231 mph on
April 12 1934, atop
Mt. Washington,
New Hampshire.
Dust in North Africa is
kicked up by high winds
and carried as high as
20,000 feet (6,100
meters), where it's
caught up in the trade
winds and carried
across the ocean. Dust
from China can make its
way to North America,
too.
Weather
Humidity:
• Amount of water vapor present in air
• As temperature increases, the amount of
water vapor it can hold increases
• Warm air = holds more water vapor
• Cool air = holds less water vapor
Weather Patterns – Part 2
Air masses,
pressure systems,
and
fronts
cause weather to change
Weather Patterns
Air Masses =
• Large bodies of air
• Its properties are similar to the part of Earth
where it formed
➢Air mass developed over land = dry
➢Air mass developed over water = wet
➢Air mass developed in tropics = warmer
➢Air mass developed in poles = colder
Weather Patterns
Air
Masses
Weather Patterns
Naming Air Masses:
• Continental = Forms Over Land (dry)
• Maritime = Forms Over Water (wet)
• Polar = Forms Over Polar Areas (cold)
• Tropical = Forms Over Tropical Areas
(Warm)
Maritime
Polar
Maritime
Tropical
Weather
Patterns
Continental
Polar
Continental
Tropical
Maritime
Polar
Maritime
Tropical
Weather Patterns
Pressure Systems =
• Measured with barometer
• Low pressure system = [L = lousy weather]
– Areas of rising air (aka - warm air = less dense)
– Usually cloudy or bad weather
– Lows are usually associated with high winds, warm air, and atmospheric lifting. Because of
this, lows normally produce clouds, precipitation, and other bad weather such as tropical
storms and cyclones.
• High pressure system = [H = happy weather]
– Areas of sinking air (aka - cool air = more dense)
– Usually means good weather
– Highs are normally caused by a phenomenon called subsidence, meaning that as the air in
the high cools it becomes denser and moves toward the ground. Pressure increases here
because more air fills the space left from the low. Subsidence also evaporates most of the
atmosphere's water vapor so high pressure systems are usually associated with clear skies
and calm weather.
Barometer
Mini-Lab = Air Density & Volume
Procedures:
1. Place the candle into your dish.
2. Slowly pour water into the dish until it is
just below the candle.
3. Light the candle. Wait a few seconds.
4. Place the beaker upside down over the
flame.
5. Watch closely!!!
6. Repeat!
Mini-Lab = Air Density & Volume
1. What takes up more volume – warm or cold air?
Why?
Warm air is less dense – the molecules are spread out.
It takes up more space (or volume). Cold air is more
dense – the molecules are more compacted. It takes
up less space (or volume).
2. Why does the water rise in the beaker?
The air in the beaker is warm, at first, because the lit
candle is warming it. Warm air in the beaker takes
up more volume, preventing water from rising inside
of it. When the candle goes out, the air inside the
beaker cools, therefore taking up less space
(volume). The water rises inside the beaker to fill the
space.
Mini-Lab = Air Pressure & Surface Area
What’s happening here?
Procedures:
air in the atmosphere exerts pressure in all
1.❖The
Place
a ruler on the table – half off and half on.
directions.
2.❖The
Tapgreater
on the the
endsurface
of the ruler
offan
ofobject
the
area,hanging
the more
table.
It should
the table easily.
can
be affected
by fall
thisofpressure.
ruler of
is sitting
on the
uncovered,
3.❖When
Placethe
a sheet
newspaper
ontable
the end
of the
there
is sitting
far less
air, therefore
it is
easier
to
ruler
onsurface
the table.
Make sure
you
flatten
tapthe
offnewspaper
the table. Itand
hasremove
much less
air pressure
as much
air
acting
upon it. as possible.
underneath
❖When you place the sheet of newspaper over the
4.half
Tap
on the
end
of the
hanging
the table.
of the
ruler
sitting
onruler
the table,
youoff
increase
the
It is much
movemore
the ruler.
surface
area.more
Now,difficult
there istomuch
pressure
5.pushing
Why? down on the ruler making it more difficult to
move.
Mini-Lab = Air Pressure Cards
Procedures:
What’s
happening here?
1. Fillair
the
beaker with
water
(almostinfull).
❖The
in plastic
the atmosphere
exerts
pressure
all
directions.
2. Fill the small plastic cup completely full of water.
❖The greater the surface area, the more an object
3. Place
the laminated
playing card on top of the
can
be affected
by this pressure.
plastic
❖When
thecup.
cup is turned upside down, the air
4. Lift the
plastic in
cup,
your other
hand
over
pressure
pushing
on place
the playing
card is
greater
thanthe
thecard,
pressure
the water
pushing
out
on the
then of
SLOWLY
turn
the cup
upside
card.down. Move your hand off of the playing card.
PLEASE DO THIS OVER THE LAB TUB!!!
5. What’s happening?
Mini-Lab = Air Pressure
(Vacuum Packed Students)
What’s happening here?
❖Air has pressure pushing all around you (from every
direction). The pressure inside our bodies is balanced with
Procedures:
the pressure
outside our bodies – otherwise we’d be crushed
1. pressure.
Squat down with a trash bag around your entire
by this
(EXCEPT
forfrom
your inside
head!)the bag, we lower the
❖When body
we remove
the air
pressure
inside
the
bag. of
The
pressures
are unbalanced.
2. Place
the
nozzle
the
vacuum against
your
❖We then
feel Cup
the mass
the
air on the
thigh.
your and
handpressure
around itofso
it doesn’t
suck
outside of the bag pushing in on us.
in the trash bag.
❖At sea level, the Earth’s atmosphere presses at 14.7 pounds
3. Getinch.
vacuum
packed
andThe
feelpressure
the pressure
per square
Air has
weight.
inside the
pushing
against
plastic bag
is lowered
byyou.
the vacuum to ~12.5 PSI and the
atmosphere on the outside of the bag is 14.7 PSI, with a
difference of 2.2 PSI, there is more pressure outside so we
feel the pressure pushing in on us.
Mini-Lab = Air Pressure
(Vacuum Packed Students)
Why Do Your Ears Pop in Airplanes?
As you go up in an airplane, the atmospheric
pressure becomes lower than the pressure of
the air inside your ears. Your ears pop
because they are trying to equalize, or match,
the pressure. The same thing happens when
the plane is on the way down and your ears
have to adjust to a higher atmospheric
pressure.
Mini-Lab
What’s happening
here?
= Air Pressure
Before heating, the can was
filled Crushers)
with water and air. By boiling the water,
(Can
the water changed states from a liquid to a gas. The water vapor pushed
the airProcedures:
that was originally inside the can out into the atmosphere.
When the can was turned upside down and placed in the water, the
1. Add 15 ml to an empty soda can.
water vapor condensed and turned back into liquid water. Water
2. Light
Bunsen
burner.
the ring
stand than
over
molecules
in thethe
liquid
state are
many Place
times closer
together
flame
thewater
wirevapor
meshthat
is centered
moleculesthe
in the
gasmaking
state. Allsure
of the
filled up the inside
of the canproperly.
turned into only a drop or two of liquid, which took up
much3.lessSet
space.
the can on the wire mesh. Heat until the water
This small amount of water cannot exert much pressure on the inside
begins to boil. You’ll see STEAM coming out of the
walls of the can, so the pressure of the air pushing from the outside of the
can.
can is great
enough to crush it. The sudden collapsing of an object
4. itsContinue
to heat
an additional
after boiling.
toward
center is called
anfor
implosion.
Natureminute
wants things
to be in a
state 5.
of equilibrium
or balance.
make
the
internal
pressure of the can
Grab the base
of theTo
HOT
can
with
the tongs.
balance with the external pressure on the can, the can implodes. Hey, air
6. QUICKLY bring the can to the ice water, turn it UPSIDE
pressure is powerful!
7.
8.
down, and plunge the mouth of it into the cold water.
WATCH the reaction!!
REPEAT with additional cans if you have some. ☺
Weather Patterns
Fronts =
• A boundary between two air masses with different
characteristics, such as density, moisture, or
temperature
• At these boundaries you sometimes get
cloudiness, precipitation or storms
• 3 types of fronts:
»Cold
»Warm
»Stationary
Weather Patterns
Fronts = Cold front
– Cold air advances toward warm air
– Warm air is pushed up quickly by cold air
– If temperature difference is large,
thunderstorms (even tornadoes) can form
Weather Patterns
Fronts = Cold front symbol
Weather Patterns
Fronts = Warm front
– Warm air advances toward cool air
– Warm air moves up & over cold front
– Can lead to long periods of precipitation
Weather Patterns
Fronts = Warm front symbol
Weather Patterns
Fronts = Stationary front
– Neither cold air or warm air moves
– Can lead to long periods of precipitation
Weather Patterns
Fronts = Stationary front symbol
https://www.youtube.com/watch?feature=player_embedded&v=9NZz-EeveJ8
Videos
Brain Pop Video – Winds
http://www.brainpop.com/science/weather/
wind/
Brain Pop Video – Weather
http://www.brainpop.com/science/weather/
weather/
El Niño & La Niña
• La Niña is characterized by unusually cold ocean
temperatures in the Pacific.
– In the U.S., typically winter temperatures are warmer
than normal in the South, and cooler than normal in
the North.
• El Niño is characterized by unusually warm ocean
temperatures in the Pacific.
– In the U.S., we might see increased rainfall, which
may lead to flooding. Droughts in the West Pacific
may also occur, sometimes leading to devastating
brush fires in Australia.
El Niño & La Niña
What is El Niño?
https://www.youtube.com/watch?v=IvmeUStFvz8&feature=player_embedded
Let’s Practice Predicting the Weather
Weather Symbols – Cloud
White = Shaded In
Cover
Weather Symbols – Wind
Direction
•Wind blows along the
line toward the circle.
•Wind is always written
as where it’s coming
from.
This wind is coming
from the northeast.
Weather Symbols – Wind
Speed
1 knot = 1.15 mph
Represents 5
Big Stick = 10 knots
Represents 10
Little Stick = 5 knots
Flag = 50 knots
Represents 50
Weather Maps
High Pressure
“Happy” Weather
Isobars =
Connects
areas with
equal
pressure
Low Pressure
“Lousy” Weather