Transcript Meteorology Lesson 1

Introduction to Meteorology
UNIT
10
STANDARDS: NCES 2.5.1,
2.5.2, 2.5.3, 2.5.4, 2.5.5, 2.6.1
LESSON 1
Lesson Objectives
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In this lesson, you will learn about:
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What determines global weather patterns
How air masses move and change
Effective weather forecasts
How to create a weather chart
How to read a weather map
Meteorology
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Meteorology
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The study of the
atmospheric
phenomena.
Clouds and
precipitation are the
main areas of study.
Climate versus Weather (Review)
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Weather
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Climate
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The current state of the
weather in a particular
area.
(It’s rainy in Raleigh)
Long term variation in
weather for a particular
area. Average weather
over time.
The Bahamas are
tropical islands.
The Causes of Weather
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Heat
Moisture
Winds
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Remember the sun’s rays heat the
earth. More energy reaches the
equator than the poles.
The moisture in the air remains
relative constant over the globe.
The global air masses stay in
motion.
Weather is a perfect example of the redistribution of solar energy around the globe.
Air Masses
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Air Mass
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Large body of air that takes on the
characteristics of an area over
which it forms.
Air masses forming over land have
less moisture than those formed
over the seas.
Classifying Air Masses (5 types)
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Classification
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Air masses are classified based on
the location of their formation.
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Warm & Dry = continental tropical
Cold & Dry = continental polar
Warm & Humid = maritime tropical
Cold & Humid = maritime polar
Cold = Arctic
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Sources of Air Masses
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Maritime Polar
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Continental Polar 
Maritime Tropical 
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Continental
Tropical
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Polar
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Form over North Pacific and
affect West Coast
Generally form in Alaska
Form in the Caribbean Sea
and Gulf of Mexico
Generally form in the
Southwest and Mexico
Arctic Basin and Siberia
Air Masses Over the United States
Section Review 10.1.1
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What is the difference between weather
and climate?
What must happen to keep the poles
from steadily cooling and the tropics
from overheating?
How has a maritime polar air mass
modified the climate of Oregon?
Coriolis Effect
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If the Earth did not rotate and the cold air from
the poles only went to the equator. Then the air
masses would only circulate in each
hemisphere.
BUT
The Earth rotates and causes a global
circulation pattern. Air masses in the Northern
Hemisphere circulate clockwise and
counterclockwise in the Southern Hemisphere.
Global Wind Systems
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Doldrums
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Poor winds found at the equator
because the circulation patterns
cancel each other out.
Trade Winds
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Equator to 30o where winds circulate.
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Between 30o and 60o and circulate
opposite to the trade winds.Flow to
the east.
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60o to the poles. Similar in direction to
the trade winds. Flow to the west.
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Westerlies
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Easterlies
Jet Streams
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Locations
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Definition
Speed
Importance
Jet streams are found where the wind
zones overlap.
Narrow bands of fast, high-altitude
westerly winds.
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Speeds approach 185 mph.
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Weather systems follow the path of
major winds. The jet stream affect the
intensity of weather system,s by
moving air of different temperatures to
from one region to another.
FRONTS
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Cause
Definition
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Interactions
The collision of different air
masses with different temperatures
and densities.
A front is a narrow region
separating two air masses of
different densities.
Interactions cause changes in
weather. Four types: cold, warm,
stationary, and occluded
Cold Fronts
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Cold dense air
advances under
warm air.
Warm air is forced up
As the warm air rises,
moisture condenses.
May produce rain to
severe thunderstorms
Warm Fronts
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Warm air advances and
forces cool air down.
Moisture condenses at
the bottom of the warm
air.
Precipitation down
through the cold air.
Precipitation occurs as
the warm ground air
meets the cool air above.
Stationary Front
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When two air masses
meet and neither
advances.
Generally do not
produce long term
precipitation patterns
Occluded Fronts
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Fast moving
cool air forced
trapped warm
air up as it
pushes against
another cold
front.
Clouds form above cold air and may condense and produce
some precipitation.
High Pressure Systems
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Winds move OUT
from the center of the
high pressure cell .
In high pressure
systems, air is forced
down toward the
ground.
Low Pressure Systems
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Winds move IN to the
center of the low
pressure cell .
In low pressure
systems, air is pulled
upward.
The upward
movement causes
high speed winds and
could become strong
storms.
Severe Storms !!
Comparison High-Low Systems
Section Review 10.1.2
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Discuss the global wind patterns
How does the jet streams affect the
movement of air masses?
What is the Coriolis Effect?
Compare high and low pressure
systems.