Weather—The AtmosphereWeather—The Atmosphere Weather is the condition of Earth’s Weather is the condition of Earth’s

atmosphere at a particular time atmosphere at a particular time and place.and place.

The atmosphere is the layer of The atmosphere is the layer of gases that surround the planet. gases that surround the planet.

The atmosphere is very thin.The atmosphere is very thin.

Earth’s atmosphere has conditions perfect for living things.

•Oxygen

•Water

•Warmth

•Protection from UV light

Composition of Composition of AtmosphereAtmosphere

Nitrogen 78%Nitrogen 78% Oxygen 21%Oxygen 21% Carbon dioxideCarbon dioxide Water vaporWater vapor (argon, neon, (argon, neon,

methane, krypton, methane, krypton, hydrogen)hydrogen)

TheThe GasesGases -- -- NitrogenNitrogen

Most abundant = NMost abundant = N22

Living things need nitrogen but we Living things need nitrogen but we can’t get it from the aircan’t get it from the air

Bacteria in the soil convert Bacteria in the soil convert nitrogen gas into useable nitrogen nitrogen gas into useable nitrogen for plantsfor plants

Animals eat plants (or animals that Animals eat plants (or animals that eat plants) to get their nitrogeneat plants) to get their nitrogen

The Gases -- OxygenThe Gases -- Oxygen

Most organisms use OMost organisms use O2 2 or or oxygen gas to burn their oxygen gas to burn their foodfood

Anything that burns uses Anything that burns uses oxygen gasoxygen gas

Ozone is OOzone is O33

Carbon DioxideCarbon Dioxide

COCO22

Small amount of the atmosphere Small amount of the atmosphere but necessary for plants who use it but necessary for plants who use it to make their foodto make their food

May cause global warmingMay cause global warming

Water VaporWater Vapor

CloudsCloudsWater in the form of a gasWater in the form of a gas

Solid ParticlesSolid Particles

Air contains tiny solid particles ofAir contains tiny solid particles of DustDust SmokeSmoke SaltSalt ChemicalsChemicals

Air QualityAir Quality

Air PollutionAir Pollution Harmful substances in the airHarmful substances in the air Most are from the burning of fossil Most are from the burning of fossil

fuelsfuels CoalCoal OilOil GasolineGasoline Diesel fuelDiesel fuel Natural gasNatural gas

ParticlesParticles

Natural Natural sourcessources VolcanoesVolcanoes Ocean Ocean

waves waves Forest firesForest fires Dust stormsDust storms PlantsPlants

Human Human ActivitiesActivities FarmingFarming Construction Construction FactoriesFactories CarsCars Making Making

electricityelectricity

SMOGSMOG Photochemical smogPhotochemical smog

Sunlight + chemicalsSunlight + chemicals Includes ozoneIncludes ozoneLos Angeles-type smogLos Angeles-type smog

Improving Air QualityImproving Air Quality

What are your ideas to What are your ideas to help make the air help make the air cleaner?cleaner?

It will be your job…It will be your job…

Air Pressure —The force Air Pressure —The force pushing on an area or pushing on an area or surfacesurface

Air has massAir has mass Air has volumeAir has volume Therefore, air has densityTherefore, air has density More molecules per volume More molecules per volume

means a greater densitymeans a greater density The higher the density, the The higher the density, the

higher the air pressurehigher the air pressure

Air Pressure is caused Air Pressure is caused by the weight of a by the weight of a column of air pushing column of air pushing down on an areadown on an area

14 pounds per square 14 pounds per square inchinch

Why don’t you feel the Why don’t you feel the weight?weight?

Measuring Air Measuring Air PressurePressure

A barometer is an A barometer is an instrument used instrument used to measure air to measure air pressure.pressure. Mercury barometer Mercury barometer

is a glass tube is a glass tube partially filled with partially filled with mercury that is mercury that is open at the bottom open at the bottom in a dish of in a dish of mercury.mercury.

The air pressure The air pressure pushing down on the pushing down on the mercury is equal to mercury is equal to the weight of the the weight of the mercury in the tube. mercury in the tube.

The mercury in the The mercury in the tube is pushed up by tube is pushed up by increasing air increasing air pressure.pressure.

Aneroid BarometerAneroid Barometer The metal The metal

chamber is chamber is sensitive to sensitive to changes in air changes in air pressure. pressure.

It has thin metal It has thin metal walls that push in walls that push in when air pressure when air pressure is high and push is high and push out when air out when air pressure is low.pressure is low.

Units of Air PressureUnits of Air Pressure Air pressure is Air pressure is

measured in two measured in two main waysmain ways Inches of mercuryInches of mercuryMillibars – one Millibars – one

inch = 33.87 inch = 33.87 millibarsmillibars

How Altitude Affects Air How Altitude Affects Air PressurePressure Air pressure Air pressure

decreases as decreases as altitude altitude increases. increases.

Air at sea Air at sea level has the level has the most air most air pressure pressure because all because all the air above the air above it is pushing it is pushing down on it.down on it.

Altitude Affects Altitude Affects DensityDensity Why is it hard to do Why is it hard to do

heavy exercise when heavy exercise when you are in a high you are in a high altitude?altitude?As you go up in altitude, the As you go up in altitude, the air is less dense. There are air is less dense. There are fewer molecules of oxygen per fewer molecules of oxygen per breath!breath!

QuizQuiz

1.1. What is the most abundant gas in What is the most abundant gas in the atmosphere?the atmosphere?

2.2. What causes most pollution?What causes most pollution?3.3. What does a barometer measure?What does a barometer measure?4.4. Layers of the atmosphere are Layers of the atmosphere are

classified by what factor?classified by what factor?5.5. The weather layer of the The weather layer of the

atmosphere is called what?atmosphere is called what?

6.6. What gas do plants use to do What gas do plants use to do photosynthesis?photosynthesis?

7.7. What gas is produced when things What gas is produced when things are burned?are burned?

8.8. When the mass of air increases, When the mass of air increases, does it become MORE or LESS does it become MORE or LESS dense?dense?

9.9. As altitude increases, does the air As altitude increases, does the air pressure INpressure IN CREASE or CREASE or DECREASE?DECREASE?

10.10. Which layer of the atmosphere has Which layer of the atmosphere has the ozone layer?the ozone layer?

11.11. Which layer of the atmosphere has Which layer of the atmosphere has the highest temperature?the highest temperature?

12.12. What instrument is used to What instrument is used to measure air pressure without a measure air pressure without a liquid?liquid?

13.13. What is a natural source of solid What is a natural source of solid particles in the air?particles in the air?

14.14. Name a human made particle in Name a human made particle in the air.the air.

15.15. Why is carbon dioxide an Why is carbon dioxide an important gas even though there important gas even though there isn’t much of it in the atmosphere?isn’t much of it in the atmosphere?