Transcript Weather patterns, Jet Stream, and Ocean Currents

WEATHER PATTERNS, JET
STREAM, AND OCEAN CURRENTS
WEATHER PATTERNS
Weather pattern’s are described as prolonged
temperature changes over a specific area for
example seasons.
 Weather patterns can also be described as a
period for which natural disasters are prevalent
ex. Hurricane season, tornado season, blizzards
 Weather patterns ARE affected by climate and
the conditions of the atmosphere at the time
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WEATHER VS. CLIMATE
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The average weather conditions for an area over a long period of time
are referred to as climate.
Climates are chiefly described by using the average temperature and
precipitation of an area.
Latitude is one of the most important factors that determines a
regions climate. Different latitudes on Earth’s surface receive
different amounts of solar energy. Solar energy determines the
temperature and wind patterns of an area, which influence the
average annual temperature and precipitation.
Climate is different from weather in that weather is the condition of
the atmosphere at a particular time. Weather conditions, such as
temperature, humidity, wind, and precipitation, vary from day to day.
Weather
Climate
AIR MASSES PG 603
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A mass of air that remains over a region of a few days acquires the
characteristics of the area over which it occurs.
A large body of air throughout which temperature and moisture are similar is
called an air mass. Air masses that form over frozen polar regions are very
cold and dry , air masses that form over tropical oceans are warm and moist.
There are 6 different types of air masses
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Continental air mass: form over large landmasses dry air
Maritime air mass: form over oceans moist air
Tropical air mass: form over the deserts of the southwestern U.S. Warm air
Polar Air Masses: form over ice and snow covered land. Cold air
Is an air mass considered part of climate or weather?
FRONTS
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Weather patterns are also described
as fronts. There are three specific
types of front that affect us: cold
front, warm front, occluded front
Where air masses of different
temperatures meet, a boundary
between them called a front is
created.
Along a front, the air doesn’t mix,
this happens because hot air rises
and cold air sinks.
Cold Fronts – When a cold, dense air
mass advances and pushes under a
warm air mass, the warm air is
forced to rise.
WARM FRONT
If air is advancing into a region of colder air, the
warmer front is formed.
 The warm less dense air slides up ad over the
colder, denser air mass.
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STATIONARY AND OCCLUDED FRONTS
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A stationary front, is a front
where a warm air mass and a
cold air mass meet but neither
advances.
An Occluded front is when a fast moving cold front
overtakes a slower warm front.
CAN YOU LABEL THIS MAP?
OCEAN CURRENTS
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The water in the ocean moves in giant streams (like
rivers) called currents.
Because there are continents in between the large
bodies of water, the currents move in different
directions depending on which continent they are in
between
Currents that move on or near the surface of the
ocean and are driven by winds are called surface
currents. Surface currents are controlled by three
factors: air currents, Earth’s rotation, and the location
of the continents.
Because wind is moving air, wind has kinetic energy.
The wind passes this energy to the ocean as the air
moves across the ocean surface causing the water to
move.
MAJOR SURFACE CURRENTS
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Equatorial Currents: located in the Atlantic, Pacific, and Indian
Ocean.
Currents in the southern hemisphere: in this hemisphere the currents
move in a counter clockwise direction. In the most southern region of
the ocean, the westward wind produces the Antartic Circumpolar
Current, no continents interrupt this current.
Gulf Stream : in the north Atlantic ocean, warm water moves thru
the Caribbean Sea and gulf of Mexico and north along the east coast
of North America in a swift, warm current.
DEEP CURRENTS
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Deep currents are cold, dense, slow moving
currents that flow far below the surface. They
form as cold water sinks to flow below warm
water.
GLOBAL WIND BELTS PG 633
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Because Earth received different amounts of solar energy at different latitudes, belts of
cool, dense air form at latitudes near the poles, while belts of warm, less dense air form
near the equator.
Differences in air pressure create wind
Global wind belts, such as the trade winds and westerlies, are a major factor affecting the
flow of ocean surface water.
The trade winds are located just north and south of the equator. In the northern
Hemisphere they blow from the northeast, in the southern hemisphere they blow from the
southeast. In both hemispheres, trade wind belts push currents westward across the
tropical latitudes of all three major oceans.
The westerlies are located in the middle latitudes. They push ocean currents eastward in
the higher latitudes of the northern and southern hemispheres.
In the equatorial belt
of low pressure,
called the doldrums,
the air rises and
cools, and water
vapor condenses. The
region has large
amounts of
precipitation.
The amount of
precipitation
generally decreases
as latitude increases.
The subtropical
highs are
between 20-30
degrees. Air
sinks, warms,
and dries. There
is little
precipitation
(deserts)
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Winds are caused by the uneven
heating of the atmosphere.
Variations in air temperature
lead to variations in air density
and pressure.
Air always moves from an area of
high pressure to an area of low
pressure, therefore there is a
general, worldwide movement of
surface air from the poles toward
the equator.
At high altitudes, the warmed
air flows from the equator
toward the poles
These differences in
temperatures and air pressures
create three wind belts in the
southern hemisphere.
The Coriolis effect also
influences wind patterns. The
Coriolis effect occurs when winds
are redirected by Earth’s
rotation. This process affects
storms like hurricanes
CORIOLIS EFFECT
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As we learned earlier, the coriolis effect occurs when
winds are redirected by Earth’s rotation.
BUT WHAT DOES THAT MEAN????
Neither wind belts nor ocean currents flow in straight
lines. They all follow a curved or circular pattern
caused by Earth’s rotation. As Earth spins on its axis,
ocean currents and wind belts curve.
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JET STREAMS
Jet streams – Narrow bands of high-speed
winds that blow in the upper troposphere and
lower stratosphere. These winds exist in the
Northern Hemisphere and Southern Hemisphere.
 One type of jet stream is the polar jet stream.
These bands of winds, can reach speeds of up to
500km/h and can affect airline routes and the
paths of storms.
 Another type of jet stream is a subtropical jet
stream. In subtropical regions, very warm
equatorial air meets the cooler air of the middle
latitudes and this jet stream forms. Unlike the
polar jet streams the subtropical jet streams do
not change much in speed or position.
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LOCAL WINDS
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Winds also exist on a scale that is much smaller than
a global scale. Movements of air are influenced by
local conditions and local temperature variations.
There are two types of local winds/breezes:
Land and sea breezes: during the day, the land’s
temperature increases where as the sea’s temperature
stays the same. As the hot air over the land rises the cooler
air over the ocean sinks creating a sea breeze. At night
when the opposite happens (land cools faster than water)
the sea breeze is replaced by a land breeze.
 Mountain and valley breezes: during the day, a valley
breeze forms when warm air from the valleys moves
upslope. At night, mountains cool more quickly than the
valleys do creating a mountain breeze.
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