Atmospheric Composition

Chapter4[pic 1]

Atmospheric composition

 Primarily gases

                   – uniform mixture to about 80 km

                     – also termed homosphere(均质层)

Homosphere=Ozonosphere+mesosphere     Troposphere+Stratosphere+Mesosphere

 对流层      同温层     中间层(50-80km)

Heterosphere= Thermosphere

 非均质层       热大气层

• Includes suspended solids and liquids

        – aerosols, particulates

• Also includes water vapour(水蒸气) as a gas

Lapse Rate

-normal LR=6.4°/1000m

Earth's energy system

-open flow system, input=output

-Electromagnetic radiation EMR is main source

-incoming EMR consist of

-short wavelengths, insolation

-insolation= incoming solar radiation

-energy inflow = 1372Wm -2

-Outgoing energy:

-Reflected shortwave radiation

-emitted, long wavelength radiation

EMR

-all object with T > 0 oK (–273.15 oC) emit EMR

-Stefan-Boltzmann law(emission rate)

   M=σ T^4 where σ=5.67*10^-8

-When T increase, wavelength of maximum radiation intensity decrease

  Wien's displacement law：

 入max = b/T    where b= 2898(umk), T is in Kelvins(K)

Sun: 6000°, radiation intensity high, In putting shorter wavelengths:

      -ultraviolet+visible light+shortwave infrared

Earth:T=15° low intensity, emitting longwave radiation: thermal infrared

Earth material affect insolation: scattering, refraction, reflection, absorption

-2/3 solar energy is absorbed by earth;             (Cloud does both)

-absorbed E emit as long wave, and atmosphere re-absorbs and counter-radiates some E back toward surface-------------------counter radiation constitutes Greenhouse effect

Energy:  equilibrium---in long term; no Eq is shorter period/smaller areas

Altitudinal(高度)，latitudinal, land-water, urban-rural

Temperature inversion: upper air warmer than lower air