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