Download Weather-Chapters13-14-15

Section 13.1

The main components of Earth that influence
weather are:
◦ the atmosphere
◦ land forms
◦ water in various forms (solid, liquid, gas)

Earth’s surface area:
◦ 70% covered by oceans
◦ 30% forms continents
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Weather: a set of environmental
conditions encountered from day
to day.
◦ Today’s weather: sunny with a few
clouds, -17 C, wind chill - 30 C, Winds from the
West at 37 km/h.
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Climate: a set of environmental conditions
averaged over many years.
◦ PEI’s climate in February: crisp and clean, temperature
ranges from -3 to -11 C.
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Read pages 500-503 and do questions 1-4 &
9 on page 503.
Accuracy of Advanced Weather Forecasts
(handout)
Use the following website to do the “Weather
Assignment”:
http://www.weatheroffice.gc.ca/canada_e.html
Section 13.2
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1.
There are four methods of energy transfer that help to
maintain the Earth’s energy balance as well as distribute
energy around the world. They all contribute to weather.
Radiation: transfer of energy by means of waves.
◦ These waves are measured using the electromagnetic
spectrum.
2.
Conduction: transfer of energy through the collision of
particles.
◦ Occurs in metals (steel), rock, sand, soil and water.
3.
4.
Convection: vertical transfer of energy by the
movement of particles in a fluid (liquid or gas).
Advection: horizontal transfer of energy by the
movement of particles in a fluid (liquid or gas).
How does Earth receive energy through radiation?
The Electromagnetic Spectrum – shows all types of
radiation that can travel through space at the
speed of light.

Energy from the Sun that
reaches the Earth will
undergo one of the
following:
◦ 27% is reflected off the
atmosphere and clouds
back into space.
◦ 3 % passes through the
atmosphere and bounce
off the Earth’s surface and
back into the atmosphere.
◦ 20% is absorbed by the
atmosphere.
◦ 50% is absorbed by the
ground or water at the
surface.

The energy that is reflected back off the surfaces of
the Earth depends on the albedo of the material.

Albedo: a percentage of light that an object reflects.

An object which absorbs energy and becomes
warmer is called a heat sink.
◦ High albedo - reflects a lot of light (Eg. white snow).
◦ Low albedo - reflects very little light (Eg. black soil).
◦ Good heat sinks: oceans and lakes.
◦ Poor heat sinks: soil and rocks.

Heat Capacity: how much heat a substance requires
to increase its temperature, or how much heat it
releases as its temperature decreases.
◦ high heat capacity: water (holds a lot of heat).
◦ low heat capacity: soil and rocks.
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Read pages 504-506 and do questions 1-10
on page 507.
How Much Do You Know? (handout BLM 13.2).
Video Response:
Concepts
Understanding Weather
Section 13.8
The Hydrosphere
◦ All of Earth’s fresh and salt water.
The Water Cycle
 Water in our atmosphere is present in 3 states:
liquid, vapour (gas) and solid. The energy from
the Sun helps circulate this water and create our
weather.
 Water is essential for humans. People settle
themselves near bodies of water (rivers, lakes,
oceans) as they serve as a source of food,
drinking water, and transportation. Weather
systems near bodies of water affect a large
number of people.
Hydrosphere
10% of the world’s
fresh water supply is
located in Canada.
Salt water
Fresh water
97.5%
2.5%
Glaciers and Polar
Ice Caps
Underground Water
87.3%
12.3%
Surface and
Atmospheric Water
0.4%
Lakes
Atmosphere
Rivers
90%
9%
1%
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Evaporation
◦ changing from liquid to gas.

Sublimation
◦ changing directly from solid to a gas.

Condensation
◦ changing from gas to liquid.

Transpiration
◦ movement of water from plants and bodies to the air.

Precipitation
◦ water that falls to the ground (rain, snow, hail, dew,
freezing rain, etc.)
Condensation
Sublimation
Transpiration
Precipitation
Evaporation
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Read pages 522-524 and do
questions 2, 3 & 4.
Water Cycle Video
pages 530-534
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The water cycle shows us that energy from the
sun and surrounding environment cause water
particles to heat up and turn to water vapour.
These particles rise in the less dense air until
they reach lower temperatures in higher altitudes
and lower pressure.
This is the formation of water droplets that are
very small. Only when thousands of these
droplets join together does a raindrop form
which is carried to earth through precipitation.
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Clouds are natures indicators of weather
conditions and weather patterns.
Understanding the characteristics of clouds
helps to predict the weather.
1.
2.
3.
Convective Clouds
◦ Are produced when air near the ground absorbs energy from
heated surfaces such as oceans, lakes, asphalt, concrete and
dirt.
Frontal Clouds
◦ Form when a front or large moving air mass meets another
air mass of a different temperature. Warm air masses are
usually less dense and contain more water vapour and will
rise above the cold air mass. Clouds form due to the
moisture cooling and condensing.
Orographic Clouds
Form when air moves up a mountain, expands at the lower
pressure and cools/condenses.
◦ http://www.curriculumbits.com/prodimages/details/geograp
hy/rainfall.swf
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Animation
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Fog is a cloud that forms near the ground.
◦ The most common is produced on clear nights
when the absence of clouds keeps the energy from
the Earth from being reflected or kept near the
surface. The air near the ground cools and water
vapour turns to fog.
◦ Fog also happens when warm air passes over snowcovered land, when moist sea air drifts over a
seashore or a cold current, or when moist air rises
up the mountains during the orographic lift.
A. Clouds are classified using two general shapes:
1.
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2.
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Cumulus Clouds – meaning “heap” which have a
billowing rounded shape. They tend to grow vertically
and often indicate unstable weather.
They tend to form as a result of:
◦ Convection currents
◦ Cold air pushing into warm air masses.
◦ Orographic lifting
Stratus Clouds – meaning “spread out” which have a
layered, flat shape. They tend to grow horizontally and
often indicate stable weather.
They form when:
◦ Warm air takes over a cold air mass.
B. Clouds are classified by their height (altitude) in
the atmosphere.
Low-level clouds keep their simple names.
1.
◦
2.
◦
3.
◦
Example: Cummulus or Stratus
Medium-level clouds start with the prefix alto
(which means higher)
Example: Altostratus
High-level clouds start with the prefix cirrus (which
means curly lock of hair)
Example: Cirrostratus
C. Clouds are subclassified by whether or not they
hold rain.
◦ True rain clouds are called nimbus clouds.
 Example: Nimbostratus
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Use your textbook to answer the rest of the
sheet (handout).
Water Cycle and Clouds Song
cirrus
cirro-stratus
Questions
 1. Describe the three main ways that clouds
form?
 2. Why doesn’t rain or snow fall from all clouds?
Read pages 522-524 and answer questions 1, 3, 4,
and 5 on page 534.
Handout: *Rain or Shine Quiz/Clouds and
Precipitation
Section 14.2
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A weather system is a set of temperature,
wind, pressure, and moisture conditions for a
certain region that moves as a unit for a
period of days.
An air mass is a large body of air that has the
same temperature and moisture throughout.
1.
Maritime Polar
◦ These air masses come from the Pacific and Atlantic Ocean and bring:
 fog and cooler temperatures in the summer.
 heavy snow and very cold temperatures in the winter.
2.
Continental Polar
◦ These air masses come from the North and bring:
 cold, dry air in both summer and winter.
3.
Maritime Tropical
◦ These air masses come from the Pacific and Atlantic Ocean and bring:
 warm, moist air in the summer
 rain or snow in the winter
4.
Continental Tropical
◦ These air masses come from over Mexico and bring:
 hot, dry air in the summer
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These air masses help keep the balance of
Earth’s energy. Convection and dominant
winds move warm air northward, and cold air
southward. When these air masses meet,
they create interesting and unpredictable
weather.
When two air masses meet, the differences in
temperature and humidity cause a boundary,
or front, to form between them. The weather
at a front is usually stormy and unsettled.
Cold Front
◦
forms when a cold air mass moves under a warm air
mass
violent storms, followed by fair, cool weather.
◦
◦
forms when warm air moves up and over a cold air mass
rain showers followed by hot, humid weather.
◦
forms when a fast moving cold air mass catches up
with a slow moving air mass
weakens the weather caused by cold or warm fronts.
◦
Warm Front
Occluded Front (Cut Off)
◦
Stationary Front
◦
◦
forms when 2 slow moving air masses collide
long periods of rain or other precipitation that lasts for
days.
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Read pages 546-548
and do questions 1-3.
Section 15.2 Weather in the News
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Watch - conditions are present for extreme
weather to occur in your area.
Advisory - severe weather, likely to cause local
problems and inconveniences, is predicted for
your area.
Warning - extreme weather is highly likely to
arrive in your area or may already be happening.
Take necessary precautions.
Section 15.3
http://news.bbc.co.uk/2/hi/5328524.stm
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a storm with lightening, thunder,
heavy rain, and sometimes hail.
In order for a thunderstorm to occur
you need:
◦ Moisture to form clouds and precipitation
◦ Very strong lifting of air (uplift) to
produce clouds which reach high in the
atmosphere.
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Thunderstorms form in 3 stages:

The sun warms the
surface of the Earth
and the air. This
warm air rises in an
updraft. This air
will condense into a
cumulus cloud,
which will continue
to grow as long as
there is warm air
rising below it.

When the cumulus
cloud is very large it
starts to rain. Also
cool air starts to enter
the cloud. Because
this air is heavier it
starts to descend in a
downdraft pulling lots
of water with it. The
updraft and downdraft
cause thunder,
lightening and heavy
rain.
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After a while the
downdrafts in the
cloud dominates
the updrafts
stopping water
drops from
forming. The storm
begins to die out
with light rain.
* This process normally last about 1 hour.
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Lightning occurs when clouds become
positively charged at the top and negatively
charged at the bottom. The charge builds up
until it is strong enough to cause lightning.
To protect yourself:
◦ Stay in a car
◦ Avoid open areas like fields,
open water, tops of hills.
◦ Never stand near or under
a tree, or utility pole
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a severe component of a thunderstorm in
which a rotating funnel of air extends from
the base of a thunderstorm cloud to the
ground.
http://esminfo.prenhall.com/science/geoani
mations/animations/Tornadoes.html

In order for a Tornado to
occur you need:
◦ Fast rising air in a
thunderstorm sometimes
begins spinning, forming a
funnel of air and moisture. As
more rising air is replaced by
cooler air at the surface, the
rotation becomes faster and
faster. This rising air causes
a pressure difference that
increases speed.
◦ Because of its shape, the
rotating tornado is called a
funnel cloud.
◦ At the centre, the wind speeds
can be as high as 500 km/h.
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The Fujita scale (F-scale) is used to rate the
intensity of a tornado based on the damage
that it causes.
◦ This scale is divided into 6 levels: F0 – F5
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To protect yourself:
◦ Try to get indoors, preferably in a basement or a
room with no windows.
◦ If you are outside, lie down in a ditch (low lying
land) and cover your head.

Read pages 584-588 and do questions
1,2,4,5,6 on page 588.
Section 15.6
http://news.bbc.co.uk/2/hi/science/nature/4588149.stm
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Cyclones are low-pressure systems that develop when
cold and warm fronts interact.
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Depending on where the hurricane happens it may have
a different name:
Cyclones
Hurricane
Typhoon
Tropical Cyclone
Where they
develop:
- Atlantic Ocean
- Caribbean Sea
- Gulf of Mexico
- Eastern Pacific
Ocean
- Western Pacific
Ocean
- China Sea
- Indian Ocean
- Australia
http://www.cbsnews.com/htdocs/natural_disasters/hurricanes/hurricanes
101.swf
http://news.bbc.co.uk/2/hi/science/nature/4588149.stm
Spiral rain bands
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Most hurricanes form off of the equator where the ocean is warm, so
as air rises it carries moisture with it. As the air rises, it cools and
condenses. The rising air turns to the left and begins rotating. The
faster the air rises, the faster the surrounding air moves and wind
speeds increase.
The centre of the hurricane is called
the eye. The eye can be 50 km wide
and the air is calm, the sky is clear.
The border of the eye is the eye wall.
At the eye wall the winds are moving
faster and the volume of rainfall is
greatest.
Hurricane wind speeds can reach
300 km/h which are less than a
tornado, but Hurricanes are much
larger and can last for days or even weeks.

Storm Surge: a huge amount of sea water
piled up by the strong winds and pushed
onto shore by a hurricane. The water level
may be more than 6 meters higher than
normal.
Section 15.7
http://canadaonline.about.com/cs/weather/p/icestorm.htm
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A severe snow storm with strong winds (greater than
55 km/h), low temperatures and reduced visibility
(less than 0.2 km).
Blizzards develop when a warm air mass filled with
moisture moves north and meets a cold Polar air
mass.
Blizzards cause whiteout conditions and make
travelling by road, water and air dangerous. We may
lose electricity and they can cause avalanches in
mountain areas.
Humidity –is the amount of water vapor in the air.
Heat wave -a period of more than three days at or above 32 ̊C.
Heat waves feel hotter with humidity.
◦ To protect yourself:
 Drink plenty of fluids to avoid dehydration
 Eat salty food to retain fluids.
Wind chill factor -is the temperature we feel on our skin. It is
caused by the air temperature and wind speed. It is always
colder than the air temperature.
◦ To protect yourself:
 Stay dry
 Stay out of the cold to prevent frost-bite and hypothermia
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Read pages 594-607.
Do questions 1,4,7 on page 597.
Do questions 1,2,3,5 on page 599.
Do questions 1,4,5,6 on page 607.
Video Response: Wonders of Weather
Extreme Weather Computer Assignment
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El Nino –a shift to warmer than average
temperatures in the tropical Pacific Ocean.
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La Nina –a shift to colder than average ocean
temperatures in the eastern Pacific