大氣科學(xué)專業(yè) 專業(yè)英語1-new

Unit

OneThe

StructureAnd

CompositionOf

TheAtmosphere第一課大氣的結(jié)構(gòu)和組成New

Wordsgaseous氣體的inhomogeneous不均勻的;inhomogeneityprofile廓線，分布altitude

高度;

height;meteorological氣象的aerological大氣學(xué)的，高空氣象WMO(World

Meteorological

Organization)世界氣象組織·

troposphere對流層tropopause對流層頂

stratopause平流層頂stratosphere

平流層mesosphere

中層mesopause中層頂thermopause熱層頂

lapse遞減thermosphere熱層exosphere散逸層transition過渡層polar極地的latitude緯度inversion逆轉(zhuǎn)，逆溫boundary邊界

tropics熱帶

atmospheric大氣的

isothermal等溫的ultraviolet(UV)紫外線interplanetary星際的ozone臭氧interaction相互作用inter-相互之間friction摩擦eddy-viscosity湍流粘性unstable

adj.不穩(wěn)定的·

Instability不穩(wěn)定性

stability穩(wěn)定性；

in+…否定（構(gòu)詞法）inaccurate不精確，invisible不可見，incompressible不可壓縮；

inhomogeneous不均勻；·

Parameter參數(shù)adiabatic絕熱的superman超人superadiabatic超絕熱的 super+..超（構(gòu)詞法）supermarket超市supercell超級單體aerosol氣溶膠photosynthetic光合的，photosynthesisequatorial赤道的

equator

赤道global全球的對流層平流層對流旺盛近地面，緯度不同厚度變；高度增來溫度減，只因熱源是地面；天氣復(fù)雜且多變，風(fēng)云雨雪較常見氣溫初穩(wěn)后升熱只因?qū)又谐粞醵嗨搅鲃犹鞖夂酶呖诊w行很適合上冷下熱高空對流電離層高層大氣電離層能反射無線電波，對無線電通訊有重要作用Like

a

fish

in

the

ocean,

man

is

confine

to

a

veryshallow

layer

of

atmosphere.The

gaseous

envelope

of

the

Earth

is

physicallyinhomogeneous

in

both

the

vertical

and

horizontaldirections,

although

the

horizontal

inhomogeneityis

much

less

marked

than

the

verticalinhomogeneity.What

is

the

Earth

atmosphere

?·

Various

criteria

have

been

devised

for

dividingthe

atmosphere

into

layers.This

division

can

be

based

on

the

nature

of

thevertical

temperature

profile,

on

the

gaseouscomposition

of

the

air

at

different

altitudes,

andthe

effect

of

the

atmosphere

on

aircraft

atdifferent

altitudes,

etc.The

division

based

on

the

variation

of

the

airtemperature

with

altitude

is

used

most

commonlyin

the

meteorological

literature.How

to

divide

the

atmosphere

into

layers?Which

criterion

is

mostcommonly

used

forlayer’s

division?According

to

a

publication

of

the

aerologicalcommission

of

the

World

MeteorologicalOrganization

(WMO)

in

1961,

the

Earth’satmosphere,

is

divided

into

five

main

layers:

thetroposphere,

the

stratosphere,

the

mesosphere,the

thermosphere

and

the

exosphere.These

layers

are

bounded

by

four

thin

transitionregions:

the

tropopause,

the

stratopause,

themesopause,

the

thermopause.thermospheremesospherestratosphere,troposphereexosphereThe

troposphere

is

the

lower

layer

of

theatmosphere

between

the

Earth’s

surface

andthe

tropopause.The

temperature

drops

with

increasing

height

inthe

troposphere,

at

a

mean

rate

of

6.5℃

perkilometer

(lapse

rate).The

upper

boundary

of

the

troposphere

lies

at

aheight

of

approximately

8

to

12

km

in

the

polarand

middle

latitudes

and

16

to

18

km

in

thetropics.In

the

polar

and

middle

latitudes

the

tropospherecontains

about

75%

of

the

total

mass

ofatmospheric

air,

while

in

the

tropics

it

containsabout

90%.·

The

tropopause

is

an

intermediate

layer

in

whicheither

a

temperature

inversion

or

an

isothermaltemperature

distribution

is

observed.polarmid-latitude

tropicsEarth’s

surface8km12km16-18kmTemp.tropopause90%75%heightThe

stratosphere

is

the

atmospheric

layer

abovethe

troposphere.In

the

stratosphere

the

temperature

eitherincreases

with

height

or

remains

nearly

constant.In

the

lower

part

of

the

stratosphere

(up

toapproximately

20km

above

the

Earth’s

surface)the

temperature

is

practically

constant

(about

-56℃).While

further

up

the

temperature

increases

withaltitude

at

a

rate

of

about

1℃/km

at

heights

of

20to

30km

and

about

2.8℃/km

at

altitudes

from

32

to

47km.Under

the

standard

conditions

the

temperature

atthe

47km

level

is

normally

-2.5℃.This

increase

in

temperature

with

height

is

due

tothe

absorption

of

UV

solar

radiation

by

ozonemolecules.It

should

be

noted

that

about

99%

of

the

totalmass

of

atmospheric

air

is

concentrated

in

thetroposphere

and

stratosphere,

which

extend

upto

an

altitude

of

30

or

35

km.The

stratopause

is

an

intermediate

layer

betweenthe

stratosphere

and

the

mesosphere

(in

thealtitude

region

from

47

to

52

km

),

in

which

thetemperature

remains

constant

at

about

0℃.-2.5℃0

℃47-52km32

to

47

kmHow

the

vertical

lapse

rate

of

temperature

changewith

height?Why

the

temperature

increase

with

height

instratosphere?Earth’s

surface2.8℃/km20

to

30

km1℃/km20

kmThe

mesosphere

is

the

atmospheric

layer

inwhich

the

temperature

continuously

decreaseswith

height

at

a

rate

of

about

2.8℃/km

up

toabout

71km

and

at

a

rate

of

2.0℃/km

from

71

to85km.At

heights

of

85

to

95km

the

temperature

rangesfrom

-85

to

-90℃.The

mesopause

is

an

intermediate

layerbetween

the

mesosphere

and

the

thermosphere(the

base

of

the

temperature-inversion

region

inthe

thermosphere).Normally

the

mesopause

has

an

altitude

of

85

to95km

and

it

is

characterized

by

a

constanttemperature

of

about

-86.5

℃.The

thermosphere

is

the

atmospheric

layerabove

the

mesopause.The

temperature

in

this

layer

increases

withincreasing

altitude,

reaching

about

2000℃

atabout

450km,

the

mean

height

of

the

upperboundary

of

the

thermosphere.The

temperature

increase

in

this

layer

is

mainlycaused

by

the

absorption

of

UV

solar

radiation

byoxygen

molecules,

which

dissociate

as

a

result

ofthis

process.The

exosphere

is

the

furthest

out

and

the

leaststudied

part

of

the

upper

atmosphere.It

is

located

above

450km

altitude.The

air

density

in

the

exosphere

is

so

low

thatatoms

and

molecules

can

escape

from

it

intointerplanetary

space.How

high

is

the

mesosphere

located

above

theEarth’s

surface?How

the

temperature

changes

with

height

in

themesosphere

?How

high

is

the

temperature

at

the

altitude

ofmesosphere?Finally,

along

with

the

above

division

of

theatmosphere,

we

will

also

make

use

of

a

divisionbased

on

the

extent

of

atmosphere

with

theEarth’s

surface.According

to

this

principle,

the

atmosphere

isusually

divided

into

a

so

called

boundary

layer(sometimes

also

called

the

friction

layer)

and

thefree

atmosphere.The

atmospheric

boundary

layer(up

to

1or

1.5

km)is

influenced

considerably

by

the

Earth’ssurface

and

by

eddy-viscosity

forces.At

the

same

time,

we

can

neglect,

as

a

firstapproximation,

the

influence

of

eddy-viscosityforces

in

the

free

atmosphere.Of

all

the

above

atmospheric

layers,

only

thetroposphere

(especially

its

boundary

layer)

ischaracterized

by

a

marked

instability

of

thevertical

distribution

of

the

meteorologicalparameters.It

is

in

this

layer

that

both

temperature

inversionsand

superadiabatic

temperature

variations

withheight

are

observed.Paragraph

1~10:

Division

of

the

atmospheric

layersParagraph

11~18:

Composition

of

the

atmosphereThe

Earth’s

atmosphere

is

a

mixture

of

gasesand

aerosols,

the

latter

being

the

name

given

to

asystem

comprised

of

small

liquid

and

solidparticles

distributed

in

the

air.Air

is

not

a

specific

gas;

rather,

it

is

a

mixture

ofmany

gases.

Some

of

them,

such

as

nitrogen,oxygen,

argon,

neon,

and

so

on,

may

beregarded

as

permanent

atmospheric

componentsthat

remain

in

fixed

proportions

to

the

total

gasvolume.Other

constituents

such

as

water

vapor,

carbondioxide,

and

ozone

vary

in

quantity

from

place

toplace

and

form

time

to

time.氧20.95%氬0.93%氮78.09%變動氣體（極微量）二氧化碳臭氧水汽氣溶膠粒子…固定氣體The

principal

sources

of

nitrogen,

the

mostabundant

constituent

of

air,

are

decaying

fromagricultural

debris,

animal

matter,

and

volcaniceruption.On

the

other

side

of

the

ledger,

nitrogen

isremoved

from

the

atmosphere

by

biologicalprocesses

involving

plants

and

sea

life.To

a

lesser

extent,

lightning

and

high-temperature

combustion

processes

convertnitrogen

gas

to

nitrogen

compounds

that

arewashed

out

of

the

atmosphere

by

rain

or

snow.The

destruction

of

nitrogen

has

in

theatmospheres

in

balance

with

production.Oxygen,

a

gas

crucial

to

life

on

Earth,

has

anaverage

residence

time

in

the

atmosphere

ofabout

3000

years.It

is

produced

by

vegetation

that,

in

thephotosynthetic

growth

process,

takes

up

carbondioxide

and

releases

oxygen.It

is

removed

from

the

atmosphere

by

humansand

animals,

whose

respiratory

systems

are

justthe

reverse

of

those

of

the

plant

communities.We

inhale

oxygen

and

exhale

carbon

dioxide.Oxygen

dissolves

in

the

lakes,

rivers

and

oceans, where

it

serves

to

maintain

marine

organisms.It

is

also

consumed

in

the

process

of

decayoforganic

matter

and

in

chemical

reactions

withmany

other

substances.For

example,

the

rusting

of

steel

involves

itsoxidation.From

the

human

point

of

view,

the

scarce,highly

variable

gases

are

of

great

importance.The

mass

of

water

vapor,

that

is,

H2O

in

agaseous

state,

in

the

atmosphere

is

relativelysmall

and

is

added

to

and

removed

from

theatmosphere

relatively

fast.As

a

result

,the

average

residence

time

of

watervapor

is

only

11

days.Water

vapor

is

the

source

of

rain

and

snow,without

which

we

could

not

survive.From

common

experiences

it

is

well

known

thatthe

water

vapor

content

of

air

varies

a

greatdeal.In

a

desert

region

the

concentration

of

watervapor

can

be

so

low

as

to

represent

only

a

tinyfraction

of

the

air

volume.At

the

other

extreme,

in

hot,

moist

air

near

sealevel,

say

over

an

equatorial

ocean,

water

vapormay

account

for

as

much

as

perhaps

5

percentof

the

air

volume.There

are

large

variations

of

atmospheric

watervapor

from

place

to

place

and

from

time

to

time,but

the

total

quantity

over

the

entire

Earth

isvirtually

constant.The

same

can

not

be

said

about

carbon

dioxide(CO2).The

concentration

of

this

sparse

but

importantgas

has

been

increasing

for

the

last

hundredyears

or

so.Carbon

dioxide

is

added

to

the

atmosphere

bythe

decay

of

plant

material

and

humus

in

the

soil,and

by

the

burning

of

fossil

fuels:coal,

oil,

andgas.The

principal

sinks

of

CO2

are

the

oceans

andplant

life

that

uses

CO2

in

photosynthesis.In

the

middle

1980s,

atmospheric

chemists

werestill

debating

about

the

effects

on

atmosphericCO2

of

burning,

harvesting

,and

clearing

of

forests.The

oceans

take

up

large

amounts

of

CO2,

abouthalf

the

amount

released

by

fossil

fuel

combustion.It

is

expected

that

this

fraction

will

diminish

withthe

passing

decades

whereas

the

total

mass

ofCO2

released

will

increase,

at

least

through

theearly

part

of

the

next

century.During

the

1980s

atmospheric

CO2

wasaccumulating

at

a

rate

of

about

1

part

per

million(ppm)

of

air

per

year,

but

it

is

expected

toincrease

more

rapidly

in

decades

to

come.In1983

it

averaged

about

340

ppm

of

air.Ozone(O3),

another

important,

highly

variable

gas,occurs

mostly

at

upper

altitudes,

but

it

is

alsofound

in

urban

localities

having

a

great

deal

ofindustry

and

automotive

traffic

and

a

generoussupply

of

sunshine.

In

cities

such

as

Los

Angeles,ozone

concentration

may

be

more

than

0.1ppm

inextreme

cases.Most

atmospheric

ozone

concentration

oftenexceed

1.0

ppm

and

may

be

as

large

as

10

ppm.They

vary

greatly

with

latitude,

season,

time

ofday,

and

weather

patterns.The

high-altitude

ozone

is

maintained

byphotochemical

reactions.The

ozone

layer

is

important

because,

byabsorbing

UV

radiation

in

the

upper

atmosphere,it

reduces

the

amount

reaching

the

surface

of

theEarth.Exposure

to

increased

doses

of

ultraviolet

rayswould

cause

more

severe

sunburns

and

increasethe

risk

of

skin

cancers.Biologists

indicate

that

a

substantial

increase

inUV

radiation

could

also

affect

other

compo