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LACEMOP
Factors that
Shape Weather
Weather & Climate
Weather : a condition of the
atmosphere in one place during a
short period of time
Climate: weather patterns typical
for an area over a long period of time
Latitude
The influence of latitude on climate is part of the
Earth-Sun Relationship
 The sun’s direct rays fall upon Earth in a
regular pattern
 This pattern correlates w/ Latitude Zones
 Within each zone, the climate follows
general patterns
CLIMATE ZONES
VEGITATION ZONES
Earth-Sun Relationships
Air Masses
Air masses take on the “weather” of the place
from which they came.
-a front — most weather changes are
caused by these.
-Convectional Precipitation:
- Typical of hot climates
- Convection occurs after morning sunshine
heats warm, moist air. Clouds form in the
afternoon and the rain falls.
Fontal Precipitation — when 2 fronts of
different temperatures meet.
Warm air forced upward by heavier, cool air.
Rising warm air cools = precipitation
Most common type
Continentality
Large bodies of water have a
moderating effect on land temperatures.
Why? Land and water absorb and store
energy at different rates.
Land changes quickly — water more
slowly.
Opposite
air blows off the water and moderates
land temperature.
Elevation
-The earth’s
atmosphere thins
as altitude increases.
Thus: as elevation increases,
temperature decreases
~ b/c thinner air retains less heat.
- Even in sunny places, mountains are
cold, snowy places year-round.
Mountain Barriers
• Can block air masses & cause precipitation.
Mountain Barriers
•Orographic Precipitation: warm moist air
forced upward when passing over a mountain.
Warm winds cool as they rise over the
mountains and clouds form.
•Windward: mountain side which faces the
ocean
• Leeward: mountain side which is in a “rain
shadow” (no precipitation received)
• Air is warm and dry on the Leeward side
Ocean Currents
• Help to distribute heat
• Carry warm water from tropics to poles
and return cold water to the Equator
• Winds affect current movement
• Air masses take on water temperature
Winds blow in constant patterns
and are called prevailing winds.
Historical Fact: Many
were named for the
direction they
blew…some were
even given names
because they were
used by trading
ships through the
region…
Doldrums: windless
area near the equator
Horse Latitudes: Historically, in order to take advantage
of the slightest wind ships would lighten their loads such as cargo, excess supplies and livestock…this also
included horses.
Wind Patterns
Trade winds -- blow from the
northeast toward the Equator
and from the southeast toward
the equator
Wind Patterns
Westerlies – prevailing winds
in the mid-latitudes blow
diagonally west to east
Wind Patterns
Polar Easterlies – blow
diagonally in the high latitudes
east to west—pushing the
cold air toward the mid
latitudes
Pressure & Wind
•Rising warm air
= low pressure
•Falling cool air
= high pressure
• Wind moves high to low
• Movement from equator to
poles and back
Wind Patterns
•Coriolis Effect: rotation of
the earth bends the patterns
of the wind
Low-Latitudes
The Tropics
between the Tropic of Cancer
and the Tropic of Capricorn
parts of this area receive direct
rays of sun all year long!
have warm to hot climates
High-Latitudes
The earth’s polar areas
When northern or southern
hemisphere is tilted toward the
sun, the poles receive
continuous, but indirect,
sunlight.
High-Latitudes
March 20th to about September 23rd
- the area north of the Arctic Circle
experiences continuous daylight or
twilight.
September 24th to about March 19th
- the area south of the Antarctic Circle
experiences continuous daylight or
twilight.
Mid-Latitudes
Northern Hemisphere - between
the Arctic Circle and the Tropic of
Cancer
Southern Hemisphere – between
the Antarctic Circle and the Tropic of
Capricorn
The most variable weather on
Earth is found here.
Mid-Latitudes
Climate – ranges from fairly hot
to fairly cold – with dramatic
seasonal changes.
Summer – receives warm
masses of air from the Tropics
Winter – receives cold masses
of air from the high latitudes