(大气科学基础)第一章---大气概述课件

1、(大气科学基础)第一章 大气概述1 大气的起源与组成(1) 大气的起源 地球的圈层： 外部大气圈、水圈、生物圈 内部地壳、地幔、地核 大气圈的作用：保护作用；使水循环；雕塑地表形态；对生物界和人类影响更为深刻2 大气起源4.5 billion years ago: hydrogen and helium primary atmosphere was lost to space H2,Hesecondary atmosphere: gases released by volcanic eruptions - outgassing - WV, CO2 , and other gases from

2、the earth interior CH4,H2,H2O,H,NH3,H2S-N2,H2O,CO2,O2Ultimately, photosynthesis reduced carbon dioxide and added oxygen to the atmosphere N2,O23（2）大气组成成分干洁空气组成成分（体积百分比）4从地面到100千米高度的大气可看为三个部分组成：干洁大气：不包含水汽的纯净大气水汽：气溶胶质粒：悬浮于空气中的液体和固体粒子5混合比单位： ppmm：质量混合比百万分（10-6） ppbm：质量混合比十亿分（ 10-9 ） pptm ：质量混合比万亿分（ 10-

3、12 ） ppmv：体积混合比百万分（ 10-6 ） ppbv：体积混合比十亿分（ 10-9 ） pptv：体积混合比万亿分（ 10-12 ）6 Average composition of the atmosphere up to an altitude of 25 kmGas NameChemical FormulaPercent VolumeNitrogen(氮)N278.08%Oxygen(氧)O220.95%* Water(水汽)H2O0 to 4%Argon(氩)Ar0.93%* Carbon Dioxide(二氧化碳)CO20.0360%Neon(氖)Ne0.0018%Heliu

4、m(氦)He0.0005%*Methane(甲烷)CH40.00017%Hydrogen(氢)H20.00005%*Nitrous Oxide(一氧化二氮)N2O0.00003%*Ozone(臭氧)O30.000004%* variable gases7 主要成分：浓度大于10-2量级 N2, O2 和氩 微量成分：浓度1-10000 ppmv H2O, CO2, CH4, 氦气，氖气，氪气等 痕量成分：浓度小于1ppmv 氢气，臭氧，氙气，氧化亚氮，一氧化氮， 二氧化氮，氨气，二氧化硫，一氧化碳等8成云致雨的必要条件主要成分微量成分水 汽 气溶胶生物体的基本成分维持生物活动的必要物质植物光合

5、作用的原料吸收紫外线，使地球上的生物免遭过量紫外线的伤害大气组成主 要 作用干洁空气CO2N2O2O3、对地面保温成云致雨的必要条件、对地面保温9各组分的作用干洁空气中各种气体所占比例基本上不变，但人类活动影响改变 二氧化碳矿物燃料燃烧、毁林“温室效应” 二氧化硫、氮氧化物矿物燃料燃烧、交通“酸雨” 碳氢化合物和氮氧化合物汽车尾气“光化学烟雾” 氟氯烃致冷剂的使用而排放，工业革命后才从无到有破坏臭氧层，产生臭氧层空洞1011 水汽随时间、地点而变化 夏季大于冬季 海上大于陆上，森林、水库水汽较多 气溶胶随地区、时间而变 冬季大于夏季 陆上大于海上，城市大于乡村Key Points Of the

6、 gases listed, nitrogen, oxygen, water vapor, carbon dioxide, methane, nitrous oxide, and ozone are extremely important to the health of the Earths biosphere Nitrogen and oxygen are the main components of the atmosphere by volume. Together these two gases make up approximately 99 % of the dry atmosp

7、here12Nitrogen is removed from the atmosphere and deposited at the Earths surface mainly by specialized nitrogen fixing bacteria, and by way of lightning through precipitation, supplying much needed nutrition for plant growth Oxygen is exchanged between the atmosphere and life through the processes

8、of photosynthesis and respiration.13 Carbon dioxide is key to climate change. The volume of this gas has increased by over 25 % in the last three hundred years Plotting by the Siple Station Ice Core Data and Mauna Loa Data part per million14 Methane is a very strong greenhouse gas. Since 1750, metha

9、ne concentrations in the atmosphere have increased by more than 140 %. The primary sources for the additional methane added to the atmosphere (in order of importance) are: rice cultivation; domestic grazing animals(畜牧业); termites(白蚂蚁); landfills(垃圾掩埋); coal mining; and, oil and gas extraction15甲烷的增长

10、16Greenhouse gas nitrous oxide is now increasing at a rate of 0.2 to 0.3 % per year. Its part in the enhancement of the greenhouse effect is minor relative to the other greenhouse gases already mentioned. However, it does have an important role in the artificial fertilization of ecosystems17 Ozones

11、role in the enhancement of the greenhouse effect has been difficult to determine. concentrations of ozone gas are found in two different regions of the Earths atmosphere. The majority of the ozone (about 97 %) found in the atmosphere is concentrated in the stratosphere at an altitude of 15 to 55 kil

12、ometers above the Earths surface. 18This stratospheric ozone provides an important service to life on the Earth as it absorbs harmful ultraviolet radiation. In recent years, levels of stratospheric ozone have been decreasing due to the buildup of human created chlorofluorocarbons in the atmosphere.

13、Since the late 1970s, scientists have noticed the development of severe holes in the ozone layer over Antarctica. Satellite measurements have indicated that the zone from 65 North to 65 South latitude has had a 3 % decrease in stratospheric ozone since 1978.19氟里昂会破坏平流层中的臭氧Ozone traps UV (SW) radiati

14、on from reaching the earth surface. Human pollutants (CFCs etc) are destroying this protective layer and causing cancers of the skin.20南极上空的臭氧洞THE ANTARCTIC HOLE IN THE OZONE LAYER21Water vapor has several very important functional roles on our planet: It redistributes heat energy on the Earth throu

15、gh latent heat energy exchange； The condensation of water vapor creates precipitation that falls to the Earths surface providing needed fresh water for plants and animals； It helps warm the Earths atmosphere through the greenhouse effect.22气溶胶粒子对辐射的吸收和散射、云雾降水的形成、大气污染以及大气光学与电学现象的产生都具有重要的作用。气溶胶粒子的来源可分为人工源和自然源两大类。23随堂小测1、地球的原始大气中，主要包含以下的气体成分：（ ）氮和氧 b. 氢和氦 c. 水汽和二氧化碳 d. 甲烷和臭氧2、当前的地球大气中，（ ）约占干空气总体积的99%氢和氧 b. 二氧化碳和氧气 c. 氮和氧 d. 氢和氮3、约75%质量的空气集中于对流层内（判断对错）4、下列大气成分中，哪些属于可变气体：（ ）氮 b.氧 c.氢 d.水汽 e. 二氧化碳 f.甲烷 g.一氧化氮h.臭氧 I.氦 J.氩 k.氪 l.氖5、大气中的主要温室气体有（ ）a.氮