Chapter 1 Introduction to the Atmosphere ATMO 1300 Spring 2010
Jan 20, 2016
Chapter 1Introduction to the AtmosphereATMO 1300Spring 2010
Weather vs. ClimateWeather Short-term variations in the sensible state of the atmosphere (e.g., hot today, rain over the weekend, etc)METEOROLOGY The study of weatherClimate Long-term state of the atmosphere (e.g., global warming)CLIMATOLOGY The study of climateThe link between meteorology and climatology
The source of energy for our atmosphere is the sun!Drives existence and motion of weather systems
General Characteristics of the AtmosphereThe atmosphere is a 3-dimensional fluid
General Characteristics of the AtmosphereVery shallow depth (relative sense) Figure from www.met.tamu.edu/class/metr452/models/2001/global.gif
General Characteristics of the AtmosphereNo defined top
Has mass, therefore weight, due to gravity
Mainly composed of invisible gas molecules and aerosols
Q: Which scenario is correct upon combining air masses of different densities? LESS DENSE (WARM)
HEIGHT MORE DENSE (COLD)
This is a STABLE situation (something has to happen externally to overturn it)That something is WEATHER!
Example: Think of a pot of water on the stove why do hot air balloons fly?
COLDCOLD HOTUNSTABLE situation, air is less dense underneath more dense air. Atmosphere always wants to achieve stability. To do, so which way must cold/warm air move?WEATHER exists to remove the imbalance. In this case, thermal imbalance leads to a thunderstorm. (Much) more later just wait COLD
Permanent Atmospheric GasesNitrogen (N2) 78%
Oxygen (O2) 21%
Argon (Ar) 1%
Variable GasesWater Vapor (H2O) (varies from ~ 0-4%)
Carbon Dioxide (CO2)
Ozone (O3)
Ozone (O3)Mainly found in the Stratosphere (a beneficial shield), but can often be found in the Troposphere (a harmful pollutant).Ozone absorbs UV radiation from the sun Photochemical reactions determine development and destruction of ozone:Creation: O2 O + O O2 + O + M = O3 + MDepletion (need ChloroFluoroCarbons, CFCs): CFCl3 + UV radiation = CFCl2 + Cl Cl + O3 = ClO + O2 ClO + O = Cl + O2
Fig. 1-8, p. 10
Fig. 1-9, p. 11
Carbon DioxideControlling factor on temperature (greenhouse gas)Increase since 1950s (intense debate regarding link to global warming)Sources include: animal respiration and combustion.
Fig. 1-3, p. 6
Fig. 1-4, p. 7
Important Facts About
Water Vapor
Water Vapor the other greenhouse gasAn invisible gasGaseous phase of water If you can see it, its not water vapor!
Water VaporAn invisible gasGaseous phase of water If you can see it, its not water vapor!Referred to as atmospheric moistureGreatest concentration in lower atmosphere (near surface of the Earth) WHY?
Water VaporHow does water vapor get into the atmosphere? By a process called EVAPORATIONLiquid water to water vapor Called a change of phase
Gas vs. Liquid GasLiquid
Fig. 1-5, p. 8
Sources of Water Vaporleft photo from webworld98.com; right photo from killamfarms.comEVAPORATIONTRANSPIRATION
Importance of Water VaporNecessary for clouds to form (clouds are composed of LIQUID water droplets CONDENSATION necessary!)
Controlling factor on temperature (greenhouse gas)
Phase transformations are a huge source of energy in the atmosphereEnergy from latent heat release (condensation) in a thunderstorm is on the order of a 1 kiloton nuclear bomb!
AerosolsSmall (microscopic) solid particles (e.g., clay, silver iodide, organic material)Combustion by-products, sea spray, dust Act as condensation nuclei the beginning of the precipitation processAffects health, visibility, optical effects
Blowing Dust in Lubbock
Welcome to Lubbock, those of you who are new to the area
Fig. 1-11, p. 12
Vertical Structure of the Atmosphere
Vertical Distribution of Mass
Vertical Distribution of Temperature
Vertical Distribution of MassDensity = mass per unit volumeDensity decreases with increasing altitude
Figure from apollo.lsc.vsc.edu/classes/met130
Atmospheric PressurePressure = Force per unit AreaRelated to Density
Its how much stuff is above you
Stuff= atmosphere
Pressure Change with HeightLike density, pressure decreases with increasing altitude.It does so at a greater rate in the lower atmosphereHere in Lubbockwe are at about 3300 ft (about 1 km) elevation
Fig. 1-13, p. 15Hurricane Katrina at its peak: 902 mbHurricane Wilma at its peak: 882 mb all time record low for Atlantic
Ideal Gas LawPart of the Physics that governs the atmosphereAtmosphere or air can be thought of as an ideal or perfect gas and follows a simple relation
Pressure x Volume = constant x TemperatureOrPressure = R x Density x Temperature
R=287.05 J/kg K
Vertical Distribution of TemperatureAverage temperature distribution FOUR layersTemperature trend determines atmospheric layers NOT A FIXED DEPTH!
Troposphere
Where most weather occurs
TroposphereFigure from www.atmos.ucla.edu/AS3 Temperature decreases with height
Amount of temperature decrease with height (e.g., -10 deg C / km) called a Lapse RateStrong cooling with height VERY important for development of thunderstorms!
TroposphereDepth varies with latitude (greatest over tropics) and season (greatest in summer)
StratosphereTemperature increases with height called an InversionContains Ozone (i.e., the ozone layer) Not much weather occurs
TropopauseBoundary between the Troposphere and Stratosphere
Mesosphere/ThermosphereMesosphere cooling with height
Thermosphere warming with height (inversion)
The IonosphereUpper Mesosphere into Thermosphere
Contains electrically charged particles called IONS
Figure from apollo.lsc.vsc.edu/classes.met130
The IonosphereAffects radio transmissionsD layer absorbs AM radio wavesD layer disappears at night, E,F layers reflect AM radio waves back to earth
Figure from apollo.lac.vsc.edu/classes/met130
The IonosphereWhere Aurora Borealis (northern lights) occurs
Photo from climate.gi.alaska.edu/Curtis
End of Chapter 1