ATMOSPHERE M E T E O R O LO G Y

Transcription

1 ATMOSPHERE M E T E O R O LO G Y

2 INTRODUCTION ATMOSPHERIC COMPOSITION The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night

3 CHEMICAL COMPOSITION ATMOSPHERIC COMPOSITION The three major constituents of air, and therefore of Earth's atmosphere, are nitrogen, oxygen, and argon By volume, dry air contains 78% nitrogen, 20.9% oxygen, 0.9% argon, 0.03% carbon dioxide, and small amounts of other gases

4 ATMOSPHERE LAYERS STRUCTURE OF THE ATMOSPHERE Atmosphere consists of layers of air masses separated by physical properties (mainly by temperature). Main layers of atmosphere (excluding exosphere) are: Thermosphere: from mesopause to 500 ~ 1000 km ( ~ ft) Mesosphere: from stratopause to 80 ~ 85 km ( ~ ft) Stratosphere: from tropopause to 50 ~ 55 km (50 to 55 km ( ~ ft) Troposphere: extends from surface to 9 ~ 17 km ( ~ feet)

5 TROPOSPHERE STRUCTURE OF THE ATMOSPHERE The lowest layer of Earth's atmosphere extends from earth surface up to 12 km on average - 9 km on poles and to 17 km on equator ( feet) The troposphere is bounded above by the tropopause, a boundary marked in most places by a temperature inversion (in troposphere temperature drops to C ( F) and goes up in stratosphere) 50% of the total mass of the atmosphere is located in the lower part (5.6 km or 18,000 ft) of the troposphere. It is most dense part of the atmosphere All atmospheric water vapor or moisture is found in the troposphere our weather is happening only in this layer 15 C (59 F)

6 STRATOSPHERE STRUCTURE OF THE ATMOSPHERE Stratosphere extends from tropopause up to 50 ~55 km ~ ft The atmospheric pressure at the top of the stratosphere is roughly 1/1000 the pressure at sea level temperatures rises with increasing altitude from C ( F) to 0 C (32 F) at the top of layer. This rise in temperature is caused by the absorption of ultraviolet radiation (UV) from the Sun by the ozone layer situated in stratosphere. The stratospheric temperature profile creates very stable atmospheric conditions - the stratosphere is almost completely free of clouds and other forms of weather.

7 80 85 km MESOSPHERE STRUCTURE OF THE ATMOSPHERE Mesosphere the layer above the stratosphere 50 km (160,000 ft) and below the thermosphere 80~85 km (260,000~280,000 ft) Temperatures drop with increasing altitude to the mesopause that marks the top of this middle layer of the atmosphere. It is the coldest place on Earth and has an average temperature around 85 C ( 120 F) mesopause stratopause tropopause noctilucent clouds km -85 C ( 120 F) 0 C (32 F) C (-68.8 F) thermospher e Mesosphere ozone layer stratosphere troposphere The air so low that very scarce water vapor at this altitude can be sublimated into polar-mesospheric noctilucent clouds

8 80 85 km THERMOSPHERE STRUCTURE OF THE ATMOSPHERE exosphere It extends from the mesopause (which separates it from the mesosphere) at an altitude of about 80~85 km (260,000~280,000 ft) up to the thermopause at an altitude range of km ( thermopause km 1500 C (2700 F) thermosphere ft) where the exosphere begins The temperature of this layer can rise as high as 1500 mesopause -85 C ( 120 F) Mesosphere C (2700 F) because of very low density of the gas stratosphere in the layer

9 ICAO STANDARD ATMOSPHERE PHYSICAL PROPERTIES At mean sea level (MSA): Temperature - 15 C (59 F) Temperature lapse rate 1.98 C per 1000ft Pressure hpa (29.92 Hg) Pressure lapse rate 1 hpa per 30ft Density kg/m3 STANDARD ATMOSPHERE

10 GAS PHYSICAL PROPERTIES Air is a mix of gases, containing particles (molecules), and these particles are moving bouncing with each other. The velocity with witch particles move related with particles kinetic energy. Increasing temperature causes faster movement of particles and demands more space for them - therefore gas takes more volume in the same pressure and become less dense. Decreasing in temperature makes particles move slower and gas shrinks and takes less volume in the same pressure

11 GAS FORMULA PHYSICAL PROPERTIES Formula, bringing relation between temperature (T), pressure (P) and volume (V): P*V = n*r*t (n amount of gas in moles; R gas constant) In other words, pressure and volume of gas directly proportional to its temperature, for example, if you fix volume, then increasing T will increase pressure; if you fix pressure, increasing T will increase volume. Proportion of the given gas always the same. gas expands with increasing temperature and shrinks with decreasing temperature

12 TEMPERATURE U.M. PHYSICAL PROPERTIES Temperature - is a way the express how subject is hot or cold (how many kinetic energy has the amount of gas). Temperature is measured in different units of measurements like: K (Kelvin) - SI (international system of units) F (Fahrenheit) used in US mostly C (Celsius) - commonly used in the rest of world To Fahrenheit from Celsius: [ F] = [ C] To Celsius from Fahrenheit: [ C] = ([ F] 32) 5 9 To Kelvin from Celsius: [K] = [ C] To Celsius from Kelvin: [ C] = [K]

13 TEMPERATURE LAPS RATE PHYSICAL PROPERTIES In troposphere temperature gradually drops from 15 C (59 F) on the MSA to C (-68.8 F) with gradient of 1.98 C per 1000 ft up to altitude of ft This is ISA (environmental) temperature laps rate

14 DRY ADIABATIC LAPS RATE PHYSICAL PROPERTIES In real dry air temperature lapse rate is 3.05 C per 1000 ft Non condensed water vapor does not affect cooling process, air cools easily It is dry adiabatic lapse rate

15 DEW POINT LAPS RATE PHYSICAL PROPERTIES When water vapor starts condensing, vapor condensation process release lantern heat and cooling gradient slows Until water vapor is not fully condensed, temperature lapse rate is 0.57 C per 1000 ft It is dew point lapse rate Lifting condensation level level where water vapor condensation begins

16 WET ADIABATIC LAPS RATE PHYSICAL PROPERTIES When water vapor fully condensed, water had released its lantern energy and starts cooling with air again. Temperature gradient increases again. Temperature lapse rate is 1.52 C per 1000 ft It is wet adiabatic lapse rate

17 HADLEY CELLS AIR CIRCULATION Temperature on equator much higher than on poles. Masses of hot less dense air raises up creating low pressure areas On the upper level of atmosphere air cools down and moves down on poles creating high pressure areas Differential in pressure on the surface creates flow of masses of the air from poles to equator This movement creates planetary circulation of the air masses called Hadley cell

18 HADLEY CELLS AIR CIRCULATION But because of more complicated processes on planet (involving planet rotation and placement of continents on the earth) this circulation divided on 3 segments on each semisphere: Hadley cell most intensive Ferrel cell circulation on opposite direction Polar cell less intensive circulation in same as Hadley cell direction

19 CORIOLIS EFFECT AIR CIRCULATION Coriolis effect deflects direction of movement of the masses of the air flowing from poles to equator to westbound for Hadley and polar cells For Ferrel cells Coriolis effect deflect direction to eastbound In northern hemisphere wind is always deflected to the right; in southern to the left NP L L H H H H 60 N 30 N Equator This creates a map of common wind directions on planet for different latitudes and directs rotation of cyclones and anticyclones: Rotation of Earth H H H H L L 30 S Cyclone type Northern hemisphere Southern hemisphere L (anticyclone) anticlockwise clockwise SP 60 S H (cyclone) clockwise Anticlockwise

20 Please visit Q/A section to prepare to the theory examination Thank you! 1.05 METEOROLOGY