Presentation on theme: "The study of Earth’s atmosphere"— Presentation transcript:
1 The study of Earth’s atmosphere MeteorologyThe study of Earth’s atmosphere
2 Weather vs. ClimateWeather: Wind, temperature, precipitation, cloud cover and air pressure. Can be localized.Climate:long-term wx conditions over a large area. Classification based upon temp. and precip.
3 Atmosphere Composition: 78 % Nitrogen 21 % Oxygen .036% Carbon Dioxide*Rest: water vapor; dust; ozone; argon* Has the most impact, meteorologically speaking
4 Refer to Atmosphere Layers Hand Out (A)Troposphere: up to ~12km. Where we live, where wx occurs.Temp.↓as altitude↑.Rate of change:6.5 oC/km.Thinnest layer(B)Stratosphere:~12km-50kmContains the O3 (Ozone) Layer
5 UV rays + O3 O2 + O O3 Stratosphere cont’d As elevation increases, temperature increases due to the absorption of radiation by the O3 LayerUV rays + O3 O2 + O O3
6 Ozone Layer and Stratosphere cont’d This rxn in the O3 Layer causes UV rays to get absorbed. If the rxn is disrupted (as in below), then holes in the O3 layer form. This allows more UV rays to reach the earth’s surface, increasing skin cancers, etc.UV rays + O3 O + O2 + CFC’sCFCO + O2The result:Depleting the Ozone Layer so there is less Ozone to react w/the UV rays, more UV rays get to Earth’s surface
7 Layers and layers continued C.)Mesosphere: extends to 80 km. As altitude Temp.Upper part called mesopause. Avg temp. -90oC
8 Just one more layer……….D.)Thermosphere: ( km) contains the ionosphere in its lower portion.Temp. increases as altitude increases due to the absorption of short-wave, high-energy solar radiation
9 Not quite done yet…………. Auroras occur in the ionosphere. Energetic electrically charged particles (mostly electrons) accelerate along themagnetic field that surrounds the Earth.They collide with gas atoms and solar radiation, causing theatoms to give off light.
10 Heat TransferConduction: transfer of heat through matter by molecular activity. Energy is transferred through collisions of one molecule to another
11 Heat TransferConvection: the movement of matter due to the differences in density which is caused by differences in temp.
12 Heat TransferRadiation:transfer of heat energy through space via electromagnetic waves. Electromagnetic waves can travel in the absence of matter (mechanical waves, like sound, can not).
13 Meet ROYGBIV (Not who….what) ROYGBIV stands for the electromagnetic spectrum (light)R=RedO=OrangeY=YellowG=GreenB=BlueI= IndigoV=VioletWhen “white” light (from the sun) is separated (like a rainbow), it separates into these colors
14 WavelengthlongshortVISBLERed Orange Yellow Green Blue Indigo VioletinfraredUltra-VioletLow Frequency – Energy High
16 ! Pressure= Force/area Pressure is measured in Pascals (Pa) 1 Pa = 1 Newton (force)/m2 (area)AIR PRESSURE is measured in milli bars (mb)1 mb = 100 PaStandard air pressure at sea level = mb (aka 29.9 inches of mercury)
17 What is needed for precipitation? Temp. of pocket of air >Temp. of environment (Tp>Te) This causes:Vertical transport, which causes Instability.. Need pocket of air to rise in order for it to cool, condense and precipitateCondensation/Moisture. USUALLY 75% relative humidity
18 THEREFORE…..IN GENERAL, precipitation will not occur when a high pressure system is in control.If the pressure is high, then the air SUBSIDES (sinks)….if it sinks will not get the instability, etc needed for precipitation.
19 So what do you get w/a high pressure system? USUALLY…fair weather, light windsTp<Te=subsidence/stable condition
20 What gives “bad” weather/precipitation? IN GENERAL, a LOW PRESSURE systemTp>Te, causing the air to rise, get the instability, condensation, etc
21 Low Pressure SystemPressure is low so the surrounding air pressure, in contrast, is high.High pressure wants to go to lowThat replacing air rises….causes the instability and condensation needed for precip/poor wx
22 What causes Pressure Differences? Temp. differences Density differencesPressure differences
23 So……WHAT causes the temp differences??????? Uneven heating/ cooling of the Earth’s surface.These cause AIR MASSES that then cause FRONTS/FRONTAL SYSTEMS
24 Air Masses Continental Polar cP) Maritime Polar(mP) mP cP Continental Tropical (cT)Page 603 in bookMaritime Tropical (mT)mTAir Masses
25 Air Masses Names and Properties Maritime Polar (mP)Continental Polar (cP)Continental Tropical(cT)Maritime Tropical (mT)Moist (from off the ocean), cold from the “poles”Dry from off the continent(land), cold from the “poles”Dry from off the land; warm from equatorMoist from off the ocean, warm from the equator
27 Warm FrontIncoming air is warmer (less dense)than air it is “replacing”Warm “over runs” air it is replacingOften get cirrus clouds as warm front approachesCan get precip. Usually not “violent”(ex: showers, drizzle)
28 Cold FrontIncoming air is colder (more dense) than the air it is replacing“Replaced” air rises quicklyGet precip that could be violent (thunderstorms, tornadoes)
29 Stationary FrontUnsettled wx stalls. Usually “drizzley”Overcast
30 Occluded Front Cold front catches up to warm front Weather can be VERY violent (more than a cold front) thunderstorms, tornadoes
31 Definitions:Dewpoint:The temperature at which air becomes totally saturated w/waterHumidity: amount of water vapor in the airRelative Humidity: air’s water vapor content to its water vapor capacity. Capacity can change w/temp. HOW/WHY?(temp. capacity )
32 Formula for RH Yeah!!! Math in Science Relative Humidity (RH)=Absolute humidity/Capacity X 100=%Ex: at 10oC capacity is 11.0g/cm3The actual humidity(absolute)might be 5.5g/cm3, so……5.5/11 x 100=50% RH