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Chapter 5
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Atmosphere and Climatic
Differentiation
Section 1 Composition and structure
of the atmosphere
Section 2 Atmospheric circulation
Section 3 Material movement
Section 4 Energy flow
Section 5 Climatic differentiation
Section 6 Atmosphere and humankind
Chapter 5
Composition and structure
of the atmosphere
Composition of the atmosphere: The earth’s surface atmosphere
is comprised of N2, O2, Ar etc. .
Structure of the atmosphere ： The atmosphere is divided into
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troposphere, stratosphere, mesosphere, thermosphere and exosphere
on elevation direction.
Troposphere: The lowest layer of the atmosphere between the earth's
surface and the tropopause, characterized by decreasing temperature
with increasing altitude,prominent convection movement, complex
and varied weather .
Stratosphere: The layer of atmosphere between tropopause and 50～55
km.
Mesosphere: The layer of atmosphere between stratopause to 80～85
km.
Thermosphere: The layer of atmosphere between the top of
mesosphere to 800 km.
Exosphere: The outermost layer of Earth's atmosphere, lying above
the thermosphere.
Chapter 5
Composition of the Atmosphere
N2
Ar
others
Composition of the Atmosphere
Chapter 5
Table Composition of the atmosphere
Composition
N2
Volume percent
0.78083
Composition
Volume percent
1.1X10-6
O2
0.20947
Kr
Xe
Ar
0.00934
Rn
0.5X10-6
CO2
0.00035
CH4
1.7X10-6
Ne
1.82X10-6
0.3X10-6
He
5.2X10-6
N2O
O3
0.1X10-6
(10～50)X10-8
The earth’s atmosphere is mainly comprised of nitrogen and
oxygen. Currently , the minor and trace constituents such as CO2, O3,
H2O and aerosols are mostly concerned. This is because these minor
constituents have distinctly space-time variation, and can severely
affect the thermal income-expenses of earth-atmosphere system, the
vertical distribution of temperature, and humankind.
Main gas composition ,content and
molecular weight of the atmosphere
Chapter 5
Table
main gas composition and content of the atmosphere
Main composition
N2
O2
Ar
CO2
O3
CH4
H2O
Percent of volume
78.08
20.95
0.93
0.03（variable）
0.000001（variable）
0.000165
variable
Average longevity/year
106
104
109
15
？
7
10days
Molecular weight
28.02
32.00
39.94
44.00
48.00
16.04
18
The atmosphere is a mixture of gases. 99% of the atmosphere
consists of Nitrogen(78%) and oxygen(21%).The remaining 1%
of the atmosphere is comprised of H2, CO2 , O3 , H2O and solid
particles etc.
The concentration change of ozone
with altitude is incontinuous.Ozone
is found in minute amounts near the
surface and increases gradually from
10km. Most of ozone is found between
10km and 50km. There is very little
ozone above 50km. Only 10% ozone is
concentrated in troposphere and most
is in stratosphere. The greatest
concentrations of ozone are found
between 20 and 30km, known as ozone
layer.
According to observation,the addition
of N2O and CFCs to the atmosphere may
decrease ozone amount in the
stratosphere, whereas the addition
of CH4 may increase ozone amount.
Altitude(km)
Chapter 5
Ozonic concentration variation
with altitude
Ozone layer
Concentration(m-3)
Chapter 5
Seasonal variation and latitude
distribution of ozone
Ozone distribution
changes with seasons
and latitudes. The
greatest concentrations
of ozone are found
near 60o latitude and
the least near equator.
In addition, the
maximum of ozone are
found in spring and the
minimum in autumn.
month
Average gross of ozone
Chapter 5
Vertical Layering of atmospheric
temperature, density and composition
The air density decreases gradually
with altitude because of the reducing
of the earth’s gravitation, and almost
equals to the density of the
interstellar gas above the atmosphere.
From surface to high altitude, except
differentia of the density and
composition, the temperature varies
distinctly. Three warmer layers and
two cooler layers are formed on
vertical direction of the atmosphere.
The atmosphere is divided into
troposphere, stratosphere, mesosphere,
thermosphere and exosphere according to
vertical temperature distribution by
WMO.
Chapter 5
Atmospheric circulation
Level pressure gradient force: It is a motivity of
pushing air from stillness to motion.
Its direction is the same as level pressure gradient, and points from high pressure to low
pressure.
Deflection force of earth rotation（Coriolis effect)： The
Coriolis effect is a
result of the earth’s rotation. This effect notes that an object in motion on the earth
surface always appears to be deflected away from its course. The apparent deflection is
to the right in the northern hemisphere and to the left in the southern hemisphere.
Atmospheric convergence:
Airflow
concentrating toward the center of a low-
pressure.
Atmospheric divergence:
Airflow fanning out and moving away from the center of a
high-pressure.
Cyclone, Anticyclone:
Cyclone are low-pressure regions of ascending, spiraling air
currents. Anticyclone are high-pressure spirals of descending or subsiding air. In the
northern hemisphere, cyclones rotate counterclockwise and anticyclones have a
clockwise spiral.
Chapter 5
Atmospheric circulation
Atmosphere circulation:With the effect of the solar radiation, the earth’s rotation,
the ground surface characteristic and friction with the ground surface, the air
is formed three-dimensional motion of different scale.
Monsoon ： Prevailing winds vary distinctly
between winter and summer.
with seasons
in a large range
Local winds ： sea and land breezes：They take place at coastal area and
alternate in direction from day to night. During the day ,sea breezes flow from
sea to land. Late at night , land breezes flow from land to sea.
Plateau monsoon：It results from thermal differentia between the plateau and
surrounding free air, and causes reversed prevailing wind systems between
winter and summer. Mountain and valley breezes：They are local winds that
alternate in direction from day to night. During the day ,the wind moves from
valleys to mountain slopes. At night, the wind blow from mountain slopes to
valleys. Foehn：As winds flow down the leeward slope after crossing the
mountains, the air is compressed and heated at a greater rate, they enter the
valley below as warm and extremely dry winds. Heat-island effect：The
urban temperature is always higher than that of suburbs and countries.
Chapter 5
The coriolis effect and
deflection of objects motion
The pressure gradient force tends to
move air from high to low pressure. For
large wind systems ,however ,the
direction of air motion will be somewhat
different.The difference is due to the
earth’s rotation ,and called Deflection
force of earth rotation or Coriolis
effect.This effect notes an object in
motion on the earth’s surface always
appears to be deflected away from its
course.The apparent deflection is to the
right in the northern hemisphere and to
the left in the southern hemisphere. The
deflective maximum are at poles. At
Equator,there is no deflection. The
directions of the force are always
perpendicular to the motion course.The
faster the object is moving, the greater
will be the apparent deflection.
North pole
Deflection to right
Equator
No deflection
Deflection to left
South
pole
Chapter 5
Cyclones and Anticyclones
A parcel of air in motion near the surface is subjected to three influences:
(1)the pressure gradient that propels the
parcel toward low pressure;(2)the
Coriolis effect that turns the parcel to
the side; and(3) friction with the ground
surface.
For low-pressure centers(left
side), the wind will be deflected into an
inward-moving spiral pattern,or inspiral.
In northern hemisphere ,the inspiral will
be counterclockwise.In the southern
hemisphere, the inspiral will be clockwise.Meteorologists use the term cyclone.
For high-pressure(right side), the
situation is reversed. Air moving outward
forms outspiral, clockwise in the
northern hemisphere and counterclockwise
in the southern hemisphere.This outspiral
is referred to as an anticyclone.
Northern
hemisphere
Cyclones
Anticyclones
Southern
hemisphere
Chapter 5
The relationship of convergence and
divergence ,cyclone and anticyclone
（after Strahler）
The figure to the right
shows an anticyclone and
a cyclone linked together
in a convection loop. In
the anticyclone, air
converges aloft and
descends in the spiraling
motion. Near the surface,
the flow diverges,
fanning out and moving
away from the center of
the anticyclone.In the
cyclone,air converges
near the surface and
spirals and upward.
Aloft,the air diverges
and spirals outward.
Convergence
Divergence
Anticyclone
Divergence
Convergence
Cyclone
Chapter 5
Single circulation cell
There is formed temperature gradient on
the earth from equator toward poles
with the heating of the solar
radiation. It causes air temperature of
the equator region to rise, the air
expands and ascends. At one time the
air over poles shrinks and descends
because of cooling. It will form
pressure gradient toward poles on upper
atmosphere, and air flows from equator
to poles. At lower atmosphere, the
pressure gradient will point toward
equator, and air flows from poles to
equator. Supposing the earth’s surface
is featureless -one without a
complicated pattern of land and water ,
and no the earth’s rotation, it will
form a single closed
circulation
between equator and pole by direct
Chapter 5
Surface atmospheric circulation
on an ideal earth(three circulation cells)
On an ideal earth-one without a
complicated pattern of land and water,
the atmosphere is only affect by the
solar radiation and the earth’s
rotation, global surface pressure
systems are: equatorial trough,two
subtropical high-pressure belts,two
subpolar low-pressure belts,and two
polar high-pressure belts.Wind systems
are northeast trades and southeast
trades, prevailing westerlies and
polar easterlies on the northern and
southern hemisphere.Along the
longitudinal direction, there form
three circulation cells: Hadley cell,
Ferrel and Polar cells.
Chapter 5
Average sea level pressure in the
northern hemisphere in July
In the northern
hemisphere in
July, main
pressure system
are: Pacific High,
Azores High,
Southern Asia Low
and Southwestern
North America Low.
The Aleutian and
Icelandic Lows
nearly disappear
from the oceans.
L
H
L
H
H
H
L
H
Chapter 5
Average sea level pressure in the
northern hemisphere in January
In the northern
hemisphere in January,
main pressure systems
are:Siberian High,
Canadian High,
Icelandic Low and
Aleutian Low. At the
same time, the
subtropical highs of
the northern
hemisphere appear
slightly south of
their average annual
position because of
the migration of the
sun toward the Tropic
of Capricorn
L
L
H
H
H
H
L
H
H
Chapter 5
Sea and Land Breezes
Sea and land breezes alternate in direction from day to night. On a clear
day,the sun heats the land surface rapidly,and a shallow air layer near the
ground is strongly warmed.The warm air expands and rises. Thus low pressure
is formed over the coastal belt.Pressure remains higher over the water.This
means that there is a pressure gradient from ocean to land,and a wind is set
in motion. At night ,the land surface cools rapidly if skies are clear.A
cooler, denser air layer of high pressure develops.Now the pressure gradient
is from land to ocean ,setting up a land breeze.
Sea and land breezes affect distinctly the coastal weather and climate.
Water vapor is transferred by Sea breeze from sea to land and makes more fogs
and low clouds,and more precipitation on the coastal belts. At the same
time,the winds adjust the coastal temperature and make there not too hot in
summer and not too cold in winter .
Sea breeze
warm
Land breeze
cool
cool
warm
Chapter 5
Qinghai-Tibet plateau and average
longitudinal circulation（Molnar，1993）
On a tall and great plateau, because of
thermal differentia between the air near the
plateau surface and surrounding free air, it
causes reversed prevailing wind systems
between winter and summer,called plateau
monsoon. Qinghai-Tibet plateau monsoon is
the most typical. In winter, a cold highpressure is formed over the plateau surface,
and air flows from plateau to surroundings.
A warm low-pressure is formed in summer, and
air flows from surroundings to plateau.
Plateau monsoon greatly affect the air
circulation and climate, especially to east
Asia and south Asia monsoon 。The direction
of plateau monsoon is the same as that of
east Asia monsoon formed by thermal
differentia between land and ocean.It makes
east Asia monsoon (special winter wind)
specially strong and more thickness.
January
July
Chapter 5 Mountain winds and Valley winds
Mountain winds and valley winds are local winds that alternate in
direction from day to night. During the day,mountain hill slopes are
heated intensely by the sun, causing air to rise. To take place of
the rising air,a current moves up valleys from the plains belowupward over rising mountain slopes, toward the summits. At night,the
hill slopes are chilled by radiation. The cooler, denser hill slope
air then moves valleyward,down the hill slopes, to the plain below.
（a）valley winds
warm
cool
(b）mountain winds
warm
cool
warm
cool
Chapter 5
Foehn winds
Foehn winds result when air
ascends a mountain range and
undergoes condensation that
dries it out and add latent
heat that slows its rate of
cooling.As the dry air descends
the leeward side of the range,
it is compressed and heated at
a greater rate.Thus they enter
the valley below as warm,dry
winds.The rapid temperature
rise brought about by such
winds has been known to damage
crops,increase forest fire
hazard,and set off avalanches.
Temperature(0C)
Chapter 5
“Urban heat-island”
City is a populous region,and has developed industries. Large man-made
heat is released by citizens, industries and vehicles, and causes urban
temperature higher than that of suburbs and countries. The city is like a
warm island, known as “urban heat-island”. The formation of “heat-island”
is because the air over city obtains sensible heat from warm buildings by
turbulent diffusion, and absorbs long- wave radiation from urban surface
and polluted layer. Because of “heat-island effect”, the mean annual
temperature of cities are higher 0.5～1℃ than that of the suburbs。
Chapter 5
Material movement
Water vapor movement：
Vertical transmission；
Horizontal transmission（transmission between high and
low latitude; transmission between land and ocean)
Dioxide dioxide movement：
CO2 diffuses and transmits from source to surroundings
and higher atmosphere.
Aerosols movement：
Aerosols diffuses and transmits from source to
surroundings and higher atmosphere.
Chapter 5
Energy flow
Energy flow between high latitude and low latitude ： It
mainly depends on global atmospheric circulation(direct and
latent heat energy and oceanic flows).
Energy flow between sea and land：In winter,oceans are heat
sources and lands are cold regions, heat energy is transferred
from ocean to land. Nearer to the ocean, more heat transferred,
higher temperature it is.
Energy flow between high and low altitude：In troposphere,
energy is transferred between high and low altitude because of
air convection.
Chapter 5
Heat energy transfer and global
energy balance（after Strahler）
The energy transfer between
equator and polar regions mainly
depends on global atmospheric
circulation (sensible and latent heat
and oceanic flows), and it varies
with latitudes and seasons. Global
heat energy transfers from surplus
regions of energy ( 350S~350N) to
deficit regions (higher latitude 350
north and south). The greatest
amount of heat is transferred near
latitude 400 at average.
Radiation deficit
Longitudinal
energy transfer
Radiation
surplus
Chapter 5
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Climatic differentiation
Temperature differentiation：Temperature distribution is affected
by the factors of latitude, ocean and land,landform and altitude etc.. Thereinto
the latitude determine zonality differentiation of temperature. and ocean and
land, landform and altitude are factors that influence non- zonality
differentiation of temperature。
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Humidity and precipitation differentiation：water vapor is
abundant over oceans and short over land. Humidity is gradually minished
from coastal to inland.
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Climatic differentiation:
Latitudinal zonality: Unequal surface
heating of the solar radiation is the dominant factor of climate formation, and
accompanying the distribution of global pressure and wind belts,and seasonal
motion, these result in climate types subrogation along latitude.
Humidity zonality the difference between ocean and land cause climatic
elements, such as temperature,pressure, directions of wind and precipitation
etc. to change with seasons, and bring differentiation of continental and
maritime climate in same latitude belt.
Vertical zonality：On different altitude of a tall and great mountain , varied
temperature and precipitation combination form different water and heat
characteristic, and cause mountain climate change along vertical direction.
Chapter 5
Average sea level
temperature in January (0C)
Chapter 5
Average sea level
temperature in July (0C)
Chapter 5
Average precipitation distribution
in the Earth （Moller,1951）
Dec.~Feb.
Average precipitation distribution
Chapter 5
in the Earth （Moller,1951)
Jun.~Aug.
The comparison between
Chapter 5
maritime and continental climate
Maritime climate
T
1. Both daily and annual range of
temperature are little. Warm in winter
and cool in summer. It is warmer than
the same latitudinal continent in
winter and cooler in summer.
2. Both the warmest and coldest
month occur later. In temperate zone,
the warmest month is August, the
coldest month is February.
3. The temperature in Autumn is
higher than that in Spring.
Continental climate
1. Both daily and annual range of
temperature are large. Cold in
winter and hot in summer.
2. Both the warmest and coldest
month occur earlier. In temperate
zone, the warmest month is July,
the coldest month is January.
3. The temperature in Spring is
higher than that in Autumn.
The comparison between
Chapter 5
maritime and continental climate
Maritime climate
P
O
t
h
e
r
s
Continental climate
1. The amount of rainfall is abundant. 1. The amount of rainfall is short.
2. Annual percipitation distribution 2. Percipition mainly concentrates in
summer.
is even.
3. Less annual percipitation variation . 3.More annual percipitation variation .
4.Convection rainfall often occurs in the
afternoon in summer.
1. High air humidity, heavy cloud 1. Low air humidity, slight cloud cover.
cover.
2. Less day with fog, more radiation
2. More day with fog, more fogs.
advection fogs.
3. High percentage of sunshine.
3. Low percentage of sunshine .
4.Slow wind speed. Obvious wind speed
4. Rapid wind speed. Little wind daily variation.
speed daily variation.
Chapter 5
Vertical climatic zone and
natural zone on the north slope
of changbai Mountain
A tall and great mountain has two
influences to climate: on the one hand,
it impedes airflow’s motion and
becomes barrier of airflow’s motion,
thereby it may result widely different
climate on two sides of a mountain,
and break the climatic latitudinal
zonality on a certain extent; On the
other hand, on different altitude of a
tall and great mountain , varied
temperature and precipitation
combinations form different water
and heat characteristics, and cause
mountain climate to change along
vertical direction, namely vertical
zonality, and form a special climatic
type-mountain climate.
Alpine desert climatic zone
Alpine shrub climatic zone
Montane birch climatic zone
Montane conifer forest climatic
zone
Montane broad-leaf forest
climatic zone
Chapter 5
Atmosphere and humankind
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Composition of the atmosphere and humankind
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Human activities and atmosphere
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Weather,climate and humankind
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Suitable temperature, humidity, wind and
sunshine are beneficial to people’s health,
whereas some conditions help in the growth of
some viruses and bacteria ,and harmful to
people’s health.