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ORIGIN AND COMPOSITION OF THE ATMOSPHERE E n v i r o n m e n t a l 1 P h y s i c s THE BIRTH OF THE EARTH: ACCRETION OF PLANETESIMALS 5·109 years Planetesimals are objects of some Km of diameters that are thought to have formed during the solar system's formation. The origin of the Solar System has been tracked by Safronov's theory about 5 billion years ago, when an initial primordial nebula made of gas (mostly hydrogen and helium) and very diffuse dust grains (carbon and silicate) started to collapse gravitationally leading to the formation of a central protostar and of a surrounding, rotating disk structure, made from the material that was not incorporated in the protostar. During this disk phase (that can last up to 100 millions years), the grains of dust grow in size very rapidly (this phenomenon being called accretion) until, after a relatively short period, they form planetesimals. These planetseimals have a composition that depends on the region where they have formed (we find rocky planetesimals in the inner parts and ices in the outer parts) and are the "bricks" of the following formation of the planets. In fact in the last phase, the accretion of planets is possible, due to the impacts between planetesimals that can glue together, forming growing objects with a composition that is still respected by the actual structure of the solar system (where, in the inner parts, wet find rocky planets, while in the outer parts, planets are gaseous). Asteroids and comets are leftover planetesimals that have not been incorporated into a planet during this period. http://www.ecology.com/archived-links/planetesimals/ 2 E n v i r o n m e n t a l P h y s i c s THE INNER STRUCTURE OF THE EARTH Structural diferentiation according to the density of different materials Inner core E n v i r o n m e n t a l Main component: Iron Solid, radius 1200 km External core Main component: Iron Líquid, radius 3470 km Mantle Iron, magnesium, aluminium, silicon and oxigen Radius 3470 km Adapted from: http://zebu.uoregon.edu/internet/images/earthstruc.gif Crust Sodium and aluminium silicate minerals Thickness 8 - 70 km http://www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html 3 P h y s i c s THE ORIGIN OF OUR ATMOSPHERE Originally formed by volatile compounds from volcanism at the earlier period of the Earth’s story. The gasses were kept back by gravity force. Since then, its composition undergone important variations because several physical, geological and biological processes. E n v i r o n m e n t a l Actual volcanic eruptions have a mean composition of 85% H2O, 10% CO2 and SO2 and nitrogen compounds (the rest). Low percentage of H2O in the actual atmosphere Low percentage of CO2 in the actual atmosphere We have to explain… Predominance of nitrogen Presence of other components of low concentration Presence of an important fraction of O2 http://www.xtec.es/~rmolins1/solar/es/planeta02.htm 4 P h y s i c s COMPOSITION OF THE ATMOSPHERE Componentes mayoritarios atmósfera Dry air (majority components) (% volumen) Composition below 100 km (percentages) N2 78% E n v i r o n m e n t a l O2 21% Ar 0.93% Dry air (majority component) (% mass) N2 76% Otros 0.04% O2 23% Ar 1.3% Water steam: Until 4% (volum) Otros 0.07% Adaptad from John M. Wallace y Peter V. Hobbs, Atmospheric Science: an introductory survey. Academic Press 5 P h y s i c s COMPOSITION OF THE ATMOSPHERE (CONTINUED) (parts per million) Minority components CO2 325 ppm (93%) Ne 18 ppm (5.2%) He 5 ppm (77%) Resto 6.5 ppm (1.9%) Kr 1 ppm (15%) H2 0.5 ppm (7.7%) Ozone: 0-12 ppm 6 E n v i r o n m e n t a l P h y s i c s WATER IN THE ATMOSPHERE Low contents of water in the actual atmosphere mb 40 P 30 Room conditions 23 mb 20 10 Both axis have not the same scale ºC 10 20 30 PC T3= 0.01 C = 273.16 K P3= 0.006112 bar 1 atm P3 TC = 374.15 C = 647.30 K PC = 221.20 bar T3 100 C TC T 7 E n v i r o n m e n t a l P h y s i c s WATER IN THE ATMOSPHERE (CONTINUED) Low atmospheric contents in water E n v i r o n m e n t a l Limited ability to keep water steam in the air Saturation and condensation Precipitation and formation of the oceans Hydrosphere Interdependence of the system atmosphere / hydrosphere http://matap.dmae.upm.es/Astrobiologia/Curso_online_UPC/capitulo11/3.html 8 P h y s i c s HYDROSPHERE Mass 1.36·1021 kg 97% Oceans Ice Subsoil Rivers & lakes Atmosphere Océano 97% Hielo 2.4% 97 % 2,4 % 0,6 % 0,02 % 0,001 % Otros 0.6% 97 2,4 0,6 Subsuelo 97% 97% 2.4% 0.6% The actual water content of the hydrosphere is two magnitude orders LOWER than that have been injected into from the origin ot the Earth Ríos y lagos 3,3% How to explain this shortfall? Atmósfera 1,7% 3.3% 0.17% * Filtration at subduction points * UV fotodisociation 9 E n v i r o n m e n t a l P h y s i c s http://geology.er.usgs.gov/eastern/plates.html The earth's surface is broken into seven large and many small moving plates. These plates, each about 50 miles thick, move relative to one another an average of a few inches a year. At convergent boundaries, plates move toward each other and collide. Where an oceanic plate collides with a continental plate, the oceanic plate tips down and slides beneath the continental plate forming a deep ocean trench (long, narrow, deep basin.) An example of this type of movement, called subduction, occurs at the boundary between the oceanic Nazca Plate and the continental South American Plate. Where continental plates collide, they form major mountain systems such as the Himalayas. 10 E n v i r o n m e n t a l P h y s i c s HYDROSPHERE. SUBDUCTION Subduction (oceanic trench) E n v i r o n m e n t a l Ocean Oceanic crust Continental crust Upper mantle Filtrations towards the mantle 11 P h y s i c s HYDROSPHERE. WATER FOTODISOCIATION Molecule of water Fotodisociation E n v i r o n m e n t a l High atmosphere, low pressure conditions H H UV high energy photons O H H O H O H H O 104º H High energy photons arise highly reactive free radicals, which recombinate as new chemical species. Specially hidrogen tends to run away because its low molecular mass. 12 P h y s i c s CARBON DIOXIDE IN THE ATMOSPHERE Low rate of carbon dioxide Estimation of carbon content in the Earth crust (relative units) Geological and biological porcesses Storing of carbon: * Rocks, salts, fossil oils * Atmosphere (free CO2) and ocean (solved CO2 * Biosphere Oxigen presence in the crust: * Iron salts, carbonates y bicarbonates Marine biosphere Continental biosphere Atmosphere (CO2) Ocean (solved CO2) Fossil oils Salts Carbonates 1 1 70 4000 800 800000 2000000 Source: John M. Wallace y Peter V. Hobbs, Atmospheric Science: an introductory survey. Academic Press. From P K Weyl, Oceanography. John Wiley & Sons, NY, 1970 Carbonates: arising by ionic exchange reactions (living beings) H2O + CO2 H2CO3 H2CO3 + Ca++ CaCO3 + 2H + 13 E n v i r o n m e n t a l P h y s i c s HUMAN ACTIVITY AND CO2 ATMOSFERIC CONTENT Concentration CO2 (ppm) 335 E n v i r o n m e n t a l 330 325 320 315 1958 1960 1962 1964 1966 1968 1970 Año 1972 1974 Data from Mauna Loa observatory (Hawaii). Adapted from John M. Wallace y Peter V. Hobbs, Atmospheric Science: an introductory survey. Concentration increasing from 1750 29% 280 ppm 1750 360 ppm Actual Based on http://zebu.uoregon.edu/1998/es202/l13.html 14 P h y s i c s NITROGEN AND MINORITARY COMPONENTS Atmospheric predominance of N2 The nitrogen content has been only slightly changed because its low reactivity Around 20% fixed as nitrates (biological activity) Other components of the atmosphere Acid rain SULPHUR: injected by volcanoes Sulphates in crust NOBLE GASES: He, Ar From radiactive desintegrations 15 E n v i r o n m e n t a l P h y s i c s OXIGEN SOURCES OF THE ATMOSPHERIC OXIGEN Water disociation (UV) 2H2O 2H2 + O2 Photosynthesis (visible light) H2O + CO2 {CH2O} + O2 Earlier living beings (reducing environment) * 4109 años E n v i r o n m e n t a l Increased O2 releasing 4108 years LIFE IN THE OCEANS Unicelular seaweed releasing O2 2-3109 años * O2 PRESENCE IN THE ATMOSPHERE AS A CONSEQUENCE OF BIOLOGICAL PROCESSES LIFE ON THE SURFACE Formation O3 Decreasing UV radiation in surface See Miller’s experiment in http://matap.dmae.upm.es/Astrobiologia/Curso_online_UPC/capitulo9/4.html 16 P h y s i c s ATMOSPHERIC PRESSURE Fluids equation: dp g dz E n v i r o n m e n t a l The air density decreases as height increses z Vertical variation >> horizontal variation Below 100 km, for every height from the ground, pressure lies within an interval of 30% of a standard value. 17 P h y s i c s ATMOSPHERIC PRESSURE (CONTINUED) dP g dz Air is a compressible fluid Density and pressure are proportional BP z dP BPg dz dP Bg dz P z Ln P Bg z P0 H P z P0 0 dP P Bg dz H 1 Bg It depends on the molecular mass of the gas P P0 exp( z / H ) H 7 km 18 E n v i r o n m e n t a l P h y s i c s ATMOSPHERIC PRESSURE (EXAMPLE) Mount Everest is the highest mountain in the Earth (8848 m). Explain which calculations may be performed to obtain the pressure on its top. Compare this pressure with the pressure in the seabed at 8848 m depth. Assume conditions of constant temperature. Data: Air density: 1.225 kg/m3; marine water density: 1030 kg/m3. Pressure and density are proportional Ground level: 0 BP0 0 1.225 kg/m 3 5 2 Hence we estimate a value for B: B 1 . 209 10 (s/m) P0 1.01325 105 Pa Ground level standard pressure Remember that... P P0 exp( z / H ) 1 H 1 8432 m Bg 1.209 105 9.81 P 1.01325 105 exp(8848 / 8432) 35481 Pa 354.8 mb From standard atmosphere calculator: P = 314.4 mb http://www.digitaldutch.com/atmoscalc/ 19 ATMOSPHERIC PRESSURE (EXAMPLE CONTINUED) Mount Everest is the highest mountain in the Earth (8848 m). Explain which calculations may be performed to obtain the pressure on its top. Compare this pressure with the pressure in the seabed at 8848 m depth. Assume conditions of constant temperature. Data: Air density: 1.225 kg/m3; marine water density: 1030 kg/m3. Calculus from standard atmosphere T 288.15 6.5 z 288.15 P 1013.25 T z given in km, T given in K 5.256 Our calculus: P P0 exp( z / H ) P 1013.25 exp( z / 8432) z (m) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 8848 9000 9500 10000 10500 11000 z (km) 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8,0 8,5 8,8 9,0 9,5 10,0 10,5 11,0 T (K) 288,2 284,9 281,7 278,4 275,2 271,9 268,7 265,4 262,2 258,9 255,7 252,4 249,2 245,9 242,7 239,4 236,2 232,9 230,6 229,7 226,4 223,2 219,9 216,7 P (mb) St. Atm. 1013,3 954,6 898,7 845,6 794,9 746,8 701,1 657,6 616,4 577,3 540,2 505,1 471,8 440,3 410,6 382,5 356,0 331,0 314,4 307,4 285,2 264,4 244,7 226,3 P (mb) Ours 1013,3 954,9 899,9 848,1 799,3 753,3 709,9 669,0 630,5 594,2 560,0 527,8 497,4 468,7 441,8 416,3 392,3 369,8 354,8 348,5 328,4 309,5 291,7 274,9 20 ATMOSPHERIC PRESSURE (EXAMPLE CONTINUED) Mount Everest is the highest mountain in the Earth (8848 m). Explain which calculations may be performed to obtain the pressure on its top. Compare this pressure with the pressure in the seabed at 8848 m depth. Assume conditions of constant temperature. Data: Air density: 1.225 kg/m3; marine water density: 1030 kg/m3. 1200,0 1000,0 P (mb) 800,0 600,0 400,0 Standard atmosphere 200,0 Exponential dropping 0,0 0,0 2,0 4,0 6,0 z (km ) 8,0 10,0 12,0 21 ATMOSPHERIC PRESSURE (EXAMPLE CONTINUED) Mount Everest is the highest mountain in the Earth (8848 m). Explain which calculations may be performed to obtain the pressure on its top. Compare this pressure with the pressure in the seabed at 8848 m depth. Assume conditions of constant temperature. Data: Air density: 1.225 kg/m3; marine water density: 1030 kg/m3. Comparison: pressure on the Everest top and pressure on the bottom of the sea Everest top 8848 m Pressure on the top P = 314.4 mb (from standard atmosphere) P = 354.8 mb The pressure exerted by a water column of height z is (from our calculus) P w gz 1030 9.8 8848 Oceanic trench Pressure on the bottom P 8.93 107 Pa 893 bar 22 -8848 m E n v i r o n m e n t a l P h y s i c s ATMOSPHERIC LAYERS 1% rest Termosphere MESOPAUSE 99% rest Mesosphere 80 km Charged particles (ionosphere) 50 km ESTRATOPAUSE Estratosphere 99.9% mass E n v i r o n m e n t a l Charged and non-charged particles Scarce collisions Very dry, O3 main concentration zone High times of permanence of particles Vertical mixture is scarce TROPOPAUSE 10 - 12 km grad T -7 K·km-1 Troposphere 80% mass, 100% water steam Short times of permanence of particles 23 P h y s i c s TROPOPAUSE HEIGHT Factors affecting the height of the tropopause Estratosphere 18 * Latitude Over the equator the tropopause lies higher than upon the poles 16 Graphics obtained using yearly mean data from http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html E n v i r o n m e n t a l Additional information: Map of tropopause pressures (mean values 1983-1998) http://www.gfdl.noaa.gov/~tjr/TROPO/TROPO.html P h y s i c s Altura (km) 14 12 * The season of the year 10 Troposphere 8 * Temperature in troposphere 6 -80 -60 -40 -20 0 20 40 60 80 Latitud (grados) When temperature is low, the tropopause goes down because the convection decreases. 24 STANDARD ATMOSPHERE • • • • Air temperatura at height 0 (sea level) is 15 ºC (288.15 K) Air pressure at height 0 is 1013.25 hPa Atmospheric air is considered as dry air and it behaves as an ideal gas Gravity acceleration is constant and its value is 980.665 cm/s2 • From sea level until 11 km the temperature decreases as height increases at a rate of 6.5 ºC/km: T = 288.15 K -( 6.5 K/km)· H (H: height in km) Throughout this layer pressure is calculated by P = 1013.25 hPa ·(288.15 K/T)^5.256 • E n v i r o n m e n t a l • • From 11 to 20 km the temperature remains constant: 216.65 K Throughout this layer pressure is calculated by P = 226.32 hPa · exp(-0,1577·(H11km)) • From 20 to 32 km the temperature increases: T = 216.65 K + (H-20 km) (H: height in km) Throughout this layer pressure is calculated by P = 54.75 hPa·(216.65K/T)^34.16319 • • 25 P h y s i c s STANDARD ATMOSPHERE (CONTINUED) • • • • From 32 to 47 km the temperature increases as height increases: T = 228.65 K + (2.8 K/km)·(H-32 km) (H: height in km) Throughout this layer pressure is calculated by P = 8.68 hPa · (228.65 K/T)^12.2011 • • • From 47 to 51 km the temperature remains constant at 270.65 K Throughout this layer pressure is calculated by P = 1.109 hPa · exp(-0,1262·(H-47km)) • The rest of upper levels can be obtained from the following references: A. Naya (Meteorología Superior en Espasa-Calpe); y, R.B.Stull (Meteorology for Scientists and Engineers)). E n v i r o n m e n t a l Source: J. Almorox, http://www.eda.etsia.upm.es/climatologia/Presion/atmosferaestandar.htm Standard atmosphere calculator: (until 86 km): http://www.digitaldutch.com/atmoscalc/ 26 P h y s i c s STANDARD ATMOSPHERE. PRESSURE PROFILE 160 Height (km) E n v i r o n m e n t a l 140 120 100 Pressure (mb) Density (g/m3) Mean free path (m) Liquid water at room conditions 106 g/m3 80 60 40 Mean path a molecule goes over before colliding another 20 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 Graphic according with data from John M. Wallace y Peter V. Hobbs, Atmospheric Science: an introductory survey. Academic Press Adapted from CRC Handbook of Chemistry and Physics, 54th Edition. CRC Press (1973) 10 102 103 27 P h y s i c s STANDARD ATMOSPHERE. TEMPERATURE PROFILE Exosphere 520 510 500 TERMOPAUSE 490 H e i g h t 160 Temperature of termosphere is highly dependent on sun activity. It may vary from 500 ºC to 1500 ºC. E n v i r o n m e n t a l Termosphere 150 We live here! 140 (km) 130 120 110 100 90 MESOPAUSE 80 70 Mesosphere 60 50 STRATOPAUSE 40 Stratosphere 30 20 10 TROPOPAUSE Troposphere -100 -50 0 50 100 150 200 500/1500 Temperature (ºC) 28 Graphics from data in http://www.windows.ucar.edu/tour/link=/earth/images/profile_jpg_image.html P h y s i c s ATMOSPHERE COMPOSITION AS A FUNCTION OF HEIGHT The atmosphere composition varies as the height increases because the following reasons: 1. Diffusion by aleatory molecular movements Diffusion tends to yield an atmosphere in which the mean molecular mass of the mixture components decreases as height increases. Each gas behaves in the same way as whether it were the only component in the mixture (ideal behaviour), and the density of each decreases exponentially as height increases. However the reference height H is different for each gas, and so the gasses having lower molecular mass are most abundant at the upper levels, because the density of the lighter gasses drops slower than that of the heavier gasses. H e i g h t H 1 Bg P P0 exp( z / H ) Could you demonstrate that really higher M implies higher B? Higher M, Higher B Lower H P Lower M, lower B Higher H 29 E n v i r o n m e n t a l P h y s i c s ATMOSPHERE COMPOSITION AS A FUNCTION OF HEIGHT (CONTINUED) 2. Mixture for convection E n v i r o n m e n t a l Convection tends to homogenize the composition of the atmosphere. At low levels the mean free path is very small, so the time required for pulling apart different components is much larger than the time the turbulences take for arising a homogeneous mixture. Mean free path vs height 160 As a consequence, at low levels the atmosphere is a system well stirred whose components are very well mixed. km 140 120 The limit is about 100 km 100 80 Above 100 km the mixture by convection is no longer as efficient as it was below, and it appears a difference in composition depending on the height. 60 40 m 20 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10 102 103 30 P h y s i c s LOSE OF GASSES FROM THE ATMOSPHERE Boltzmann constant k = 1.38·10-23 J K-1 Most probable velocity: v T: Absolute temperature 2kT M m m: Mass of the hidrogen atom E M: Molecular weight of a particular gas species n v Escape velocity: that velocity in what the kinetic energy of a particle is big enough i to run away towards the infinitum. r ( At a height of 500 km, the escape velocity from the Earth is about 11 kms-1) o n m Temperature at 500 km is 600 ºC Most probable velocity 3 kms-1 e n t Fraction of molecules with velocity equal to escape velocity a l Most probable velocity Hidrogen 3 kms-1 10 -6 Oxigen 0.8 kms-1 10 -84 The lighter gasses did escape along the geological eras, so its actual abundance is low http://www.iitap.iastate.edu/gccourse/chem/evol/evol_lecture.html 31 P h y s i c s WIND Wind is the moving air from one place to another over the Earth surface. The air flux is related (among other causes) with pressure differences. The change in pressure measured across a given distance is called a pressure gradient. Pressure is a scalar magnitude Pressure gradient P ur r + GRADIENT DIRECTION: THAT OF FASTER VARIATION OF THE SCALAR MAGNITUDE 1016 1020 The air tends to move against the pressure gradient grad P 1024 ur -grad P Blue arrows indicate the sense opposite to that of the gradient pressure Do we conclude that wind moves as the blue arrows show? GRADIENT SENSE: TOWARDS HIGHER VALUES OF THE MAGNITUDE NO! …we need also consider the rotation of the Earth! 32 E n v i r o n m e n t a l P h y s i c s EARTH ROTATION EFFECTS North Pole a aR 2 vR r E Centripetal force n 2 vR v Coriolis 2 vR vR i Acceleration measured r in a rotating reference frame o n m Acceleration measured e in an inertial reference frame n aR a 2 vR r t a Trajectory within an inertial reference frame l Trajectory within an accelerating reference frame Within an rotating reference frame a Coriolis force proportional to 2 vR appears, beeing responsible for the observed deviation 2 vR vR 33 P h y s i c s CORIOLIS DEVIATION Seen from a point over the surface N NORTHERN HEMISPHERE 2 vR 2 vR vR Deviation on the right-hand side respect the sense of the movement 2 vR S vR 2 vR Deviation on the left-hand side respect the sense of the movement E n v i r o Coriolis deviation n m e SOUTHERN HEMISPHERE n t a l Coriolis P deviation h Sense of the y movement s i c 34 s Sense of the movement GEOSTROPHIC WINDS Remember: if the Earth would not spin around its polar axis, the movement of the air masses will occur in the opposite sense to that the pressure gradient. E n v Pressure gradient i r o n m e n t … and so on, up to the situation is… a l Geostrophic winds: winds balanced by the Coriolis and Pressure Gradient forces Northern hemisphere B Gradient force -grad P Coriolis force, proportional to 2 vR B A http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/geos.rxml A …geostrophic winds blowing parallel to isobars 35 P h y s i c s ANTICYCLONES AND STORMS L Northern hemisphere: The Coriolis force arises deviation to the right Within an anticyclone (H) the winds turn clockwise E n v Within a storm (L) the i winds turn anticlockwise r o n Southern hemisphere: m The Coriolis force e arises deviation to the n t left a Within an anticyclone l H H (H) the winds turn anticlockwise L Within a storm (L) the winds turn clockwise 36 P h y s i c s ATMOSPHERIC GENERAL FLOW 1 Polar cell 2 Ferrell cell 3 Hadley cell Simple model Intertropical convergence zone E n v i r o n m e n t a l Air going down on the poles (cold areas) and air ascending on the equator (warm areas) THIS SIMPLE MODEL HAVEN’T IN MIND THE EARTH’S ROTATION http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Easterly_Waves/Trade_Winds/Trade_Winds.html 37 P h y s i c s ATMOSPHERIC GENERAL FLOW (CONTINUED) E n v i r o n m e n t a l 38 P h y s i c s WESTERN WINDS NEAR POLAR ZONES Polar Arctic Circle Polar Antarctic Circle E n v i r o n m e n t a l ARCTIC ANTARCTIC Relationship with the ozone hole over Antarctica 39 P h y s i c s PLANETARY BOUNDARY LAYER Transport phenomena within PBL are related with turbulence Troposphere The planetary boundary layer (PBL) is the atmospheric region, nearest the Earth surface (300-3000 m thickness), where it occurs the most of exchanges of energy 40 and matter. It is the zone where the interaction surface-atmosphere occurs. E n v i r o n m e n t a l P h y s i c s PLANETARY BOUNDARY LAYER (CONTINUED) Turbulence: whirlpools arising from several causes 10 1 SURFACE ROUGHNESS SURFACE LAYER 100 TROPOSPHERE EXTERN LAYER BASE OF THE CLOUDS ROUGHNESS LAYER Height (magnitude order, m) 1000 LIMIT LAYER (PBL) TROPOPAUSE 10000 The planetary boundary layer is the part of the troposhpere directly influenced by the Earth surface. It is able to answer to the stimulation by surface forces wihin a temporal scale of 1 hour or less. The forces associated with the Earth’s surface include drag friction, heat transfer, evaporation and transpiration, contaminant releasing and ground features able to modify the air flux. 41 E n v i r o n m e n t a l P h y s i c s DAILY VARIATION OF THE PBL Sunrise Surface warming PBL stirring PBL increasing thickness Puesta de Sol Typical values at the end of the evening 1 km (0.2 km 5 km) 1 km (0.2 km-5 km) Sunset Night begins Surface cooling Turbulence drops or disappears 100 m (20 m - 500 m) PBL thickness dropping Typical values 100 m (20 m - 500 m) Wind, temperature and other properties of the PBL undergo fewer daily variations over vast water surfaces as oceans and great lakes than those over lands. This is because the greater specific heat of water. 42 E n v i r o n m e n t a l P h y s i c s TEMPERATURE DAILY CYCLE Height 10.0 m 05:00 08:00 10:00 12:00 15:00 18:00 2.40 m 1.20 m 60 cm 30 cm 15 cm -2 cm -5 cm -15 cm T (ºC) 30 35 40 45 Typical summer profiles (land) (data: July and August mean, based on A. H. Strahler, Geografía Física) 50 43 WATER CYCLE Precipitation 13·1012 m3 99·1012 m3/ year Oceans 423·1012 m3/ year 1350·1015 m3 Land 62·1012 m3/ year 33.6·1015 m3 Based on http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/bdgt.rxml F í s i c a A m b i e n t a l 37·1012 m3/ year 324·1012 m3/ year 99·1012 m3/ year Evaporation & transpiration Undergraound and surface water 324·1012 m3/ year m3/year Atmosphere Precipitation 423·1012 361·1012 m3/ year 361·1012 m3/year 62·1012 m3/year Evaporation ATMOSPHERIC BUDGET 44 S. Pal Arya, Introduction to Micrometeorology, 2th Edition. University Press. Roland B. Stull, An Introduction to Boundary Layer Meteorology, Kluwer Academic Publishers Coriolis acceleration http://zebu.uoregon.edu/~js/glossary/coriolis_effect.html http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml Anticyclons http://vppx134.vp.ehu.es/met/html/diccio/anticicl.htm Storms http://vppx134.vp.ehu.es/met/html/diccio/borrasca.htm http://www.rc-soar.com/tech/thermals.htm http://f4bscale.worldonline.co.uk/Thermals.htm 45