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Meteorology / Weather
Chapter 38
Standards
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5 a, b
6:a, b
Objectives:
Student will be able to describe weather and
climate.
 Students will be able to describe effects on
climate of latitude, elevation, topography
and proximity to large bodies of water and
cold or warm ocean currents.
What is Meteorology?
 The study of
atmospheric
phenomenon.
 Clouds, raindrops,
snowflakes, fog, dust,
and rainbow.
 Hydrometers- water
droplets and
precipitation
 Lithometers- smoke,
haze, dust, and
condensation nuclei.
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What is weather?
Give three examples of weather.
Explain hydrometer
Explain lithometer
Weather vs. Climate
 Weather- the current
state of the
atmosphere
 Climate- Long term
variations in weather
for a particular area
Explain the difference
between weather and
climate.
How is radiation distributed?
 Earth feels hotter in the afternoon than in
the morning or evening.
 The suns rays hit the Earth at different
angles.
– Morning and Evening it is at a low angle
therefore spreading out more
 Same amount of energy over a larger area
– Afternoon Suns rays hit Earth more directly
Why is it hotter in the
afternoon than in the
morning or evening?
 This explains why the tropical regions are
hotter and the poles colder
 Tropical regions remain at a fairly constant
temperature because the heat is
redistributed.
 Continual motion of air and water relocate
heat on Earths surface, ocean and
atmosphere. Creates a balance.
 Why does tropical regions stay
at a fairly constant
temperature?
 What happens to all the heat in
the tropical regions?
Air Masses
 Air Mass is a large body of air that takes on
the characteristics of the area over which it
forms.
 Area where it forms is called a source
region, take on the temperature of that area.
– Land air masses contain less moisture
– Water air masses contain more moisture
 Explain an air mass.
 How do land air masses and
water air masses differ?
 Identify what is a source region.
Air Mass Modification
 An air mass is
modified by the
exchange of heat or
moisture with the
surface over which an
air mass travels.
Explain the modification of
an air mass.
Wind Formation
 Wind is caused by the uneven heating of
Earth which creates areas of high pressure
differences in the atmosphere
 Wind is the movement of air from an area of
high pressure to an area of lower pressure
How is wind formed?
Explain how wind flows.
The Coriolis Effect
 The effect of Earth’s rotation on the
movement of air masses
 Changes the direction of the air flow
 Wind influences weather
 Determines when and where ships and
planes can travel
 Explain the coriolis effect?
 What does the coriolis effect influence?
 In what pattern does the coriolis effect
move currents in the Northern and
Southern Hemispheres.
Review Sheet # 1
 1. What is meteorology?
 2. Define weather, climate, hydrometers and
lithometers
 3. Explain how radiation is distributed to earth.
 4. Why do tropical regions stay hot?
 5. How is a balance maintained on earth?
 6. What are air masses and how are they
modified?
 7. How is wind formed?
 8. Explain the coriolis effect
Wind Systems
 Doldrums are windless zones at the equator
3 Types of Surface winds
 Trade Winds
 Prevailing Westerlies
 Polar Easterlies
 Name the 3 types of wind
systems.
Trade Winds
 Between the equator 30 degrees latitude
north or south
 Steady winds flow that flow to the southwest
in the northern hemisphere
 In the southern hemisphere, they blow
toward the northwest
 Where are trade winds located?
 What direction does the trade winds travel
in the northern hemisphere?
 What direction does the trade winds travel in
the southern hemisphere?
Prevailing Westerlies
 Blow in the opposite directions of trade
winds
 Between 30 degrees and 60 degrees
latitude north and south of the equator
 Responsible for most of the movement of
weather across the U.S. and Canada
Prevailing Westerlies
 In the northern hemisphere, the winds blow
from the southwest to the northeast
 In the southern hemisphere, the winds blow
from the northwest to the southeast
 What wind system is responsible for the
movement of weather in Canada and US?
 What direction does the prevailing winds
blow?
 What latitude are the prevailing winds
located in the northern and southern
hemispheres?
Polar Easterlies
 At the North Pole the winds blow from the
northeast to the southwest
 Near the South Pole the winds blow from
the southeast to the northwest
Jet Streams
 Narrow belts of strong winds that blow near
the top of the troposphere
Daily and Seasonal Winds
 Convection currents cause sea breezes and
land breezes
 Sea breezes occur during the day
 Air overhead is heated by conduction, which
becomes less dense and is forced upward
by cooler denser air moving in land from the
ocean
 This results in convection currents
Land Breezes
 Movement of air toward the water
 The cool dense air from the land moves
out over the water, pushing the warm air
over the water upward
 This occurs
at night
Review Sheet # 2
 1. Name three types of wind systems.
 2. Define doldrums
 3. Explain trade winds, prevailing winds,
polar easterlies, and jet streams.
 4. Explain convection currents
 5. Explain land breeze circulation.
 6. When do sea breezes occur?
 7. When do land breezes occur?
Fronts
 A front is a narrow area where two air
masses meet. Different types of weather
results from different fronts.
– Cold front
– Warm Front
– Stationary Front
– Occluded Front
Cold Front
 Cold air forces warm
air up.
 Moves very quickly
 Clouds, showers, and
thunder storms are
associated with this
front.
 Represented with a
blue line with triangles.
Warm Front
 Warm air displaces
cold air.
 Moves slowly
 Extensive cloudiness
and precipitation
 Represented by a red
line and half circles
Stationary Front
 Two air masses meet and
do not advance on one
another.
 Caused by both air
masses to have been so
modified that their
pressure gradient and
temperature differences
are small.
 Some rain and clouds can
occur
 Represented by a blue line
with triangles on one side
and half circles on another.
Occluded Front
 Cold air mass over
takes a warm air mass.
 Precipitation occurs at
this type of front.
 Purple line with
alternating triangles
and half circles.
Hurricane
 Large, low pressure, rotating,
storms called tropical storms
or cyclones.
 The strongest tropical storms
are called hurricanes.
 Formed from warm water and
a disturbance that pushes the
warm air up and stay
suspended.
 Warm air is a hurricanes fuel.
 Category 3 tropical storms
are called hurricanes.
Tornado
 A tornado is a violent,
whirling column of air in
contact with the ground.
 Tornados are associated
with severe storms, called
super cells.
 Tornados vary in size and
intensity.
 Usually form in the spring
in the late afternoon or
evening.
Lightning
 In a cumulonimbus atoms are
separated.
 A negative atom “step leader”
descends from the cloud
towards earth.
 A return stroke from earth made
up of positive ions rush to meet
the negative atoms.
 The illumination of lightning is
the exchange of energy.
 Thunder is the sound of the
energy produced from the
exchange of energy
Review Sheet # 3
 1. Name the four types of fronts.
 2. Draw the symbol that represents each of the
fronts.
 3. What type of weather results from a cold front?
 4. What type of weather results from a warm front?
 5. What type of weather results from an occluded
front?
 6. What type of weather results from a stationary
front?
 7. Identify the difference between a hurricane and
tornado.
 8. How does lightning form?