Chapter 1-The AtmosphereChapter 1-The Atmosphere

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Section 1- The Air around YouSection 1- The Air around You

WeatherWeather – the condition of Earth’s – the condition of Earth’s atmosphere at a particular time and place.atmosphere at a particular time and place.

AtmosphereAtmosphere – the layer of gases that – the layer of gases that surrounds the planet. surrounds the planet.

- The Earth’s atmosphere makes conditions - The Earth’s atmosphere makes conditions on Earth suitable for living things.on Earth suitable for living things.

What is the atmosphere made of?What is the atmosphere made of?

Earth’s atmosphere is made up of:Earth’s atmosphere is made up of:

– NitrogenNitrogen– OxygenOxygen– Carbon dioxideCarbon dioxide– Water vaporWater vapor– Other gasesOther gases– Particles of liquids and solidsParticles of liquids and solids

Gases in the AtmosphereGases in the Atmosphere

NitrogenNitrogen

Nitrogen is essential for all living things.Nitrogen is essential for all living things.

Most living things cannot take nitrogen, the Most living things cannot take nitrogen, the gas, directly from the air. It needs to be gas, directly from the air. It needs to be converted by plants to nitrates then to converted by plants to nitrates then to proteins. proteins.

OxygenOxygen

Oxygen is also needed by living things. Oxygen is also needed by living things.

Animals can take this gas directly from the air Animals can take this gas directly from the air and plants release it as waste. and plants release it as waste.

All fuels use oxygen to burn.All fuels use oxygen to burn.

– Ex. Cars, candles, campfire, etc.Ex. Cars, candles, campfire, etc.

Carbon DioxideCarbon Dioxide

Carbon dioxide is essential for plants. Carbon dioxide is essential for plants.

Plants need carbon dioxide to produce food. Plants need carbon dioxide to produce food. Animals need oxygen to live. Thus each Animals need oxygen to live. Thus each gives off the opposite as waste.gives off the opposite as waste.

Carbon DioxideCarbon Dioxide

Fuels like coal and gasoline give off COFuels like coal and gasoline give off CO22..

Rising CORising CO2 2 levels in the atmosphere rises levels in the atmosphere rises

the temperature of the Earth. the temperature of the Earth.

Everything elseEverything else Water vapor is HWater vapor is H22O in the form of a gas.O in the form of a gas.

The amount of water vapor varies from place to The amount of water vapor varies from place to place and time to time. place and time to time.

Particles in the atmosphere might be:Particles in the atmosphere might be:

– DustDust– SmokeSmoke– SaltSalt

Section 3- Air PressureSection 3- Air Pressure

Since air has mass, it also has other Since air has mass, it also has other properties like density and pressure.properties like density and pressure.

– Density = Density = MassMass

volumevolume

– If a substance is more dense, then it has more If a substance is more dense, then it has more molecules per unit of volume. So it exerts more molecules per unit of volume. So it exerts more pressure.pressure.

PressurePressure

Pressure – the force pushing on an area or Pressure – the force pushing on an area or surface. surface.

Air pressure – the result of the weight of a Air pressure – the result of the weight of a column of air pushing down on an area.column of air pushing down on an area.

Mass, Volume,and DensityMass, Volume,and Density

CauseCause EffectEffect

If massIf mass and volumeand volume then densitythen density

increasesincreases stays the samestays the same a.a.

b.b. stays the same,stays the same, decreasesdecreases

stays the samestays the same decreases,decreases, c.c.

stays the samestays the same d.d. decreasesdecreases

Measuring Air PressureMeasuring Air Pressure

Barometer – is an instrument that is used to Barometer – is an instrument that is used to measure changes in the air pressure. measure changes in the air pressure.

– There are two kinds of barometers:There are two kinds of barometers:

MercuryMercury AneroidAneroid

Mercury BarometersMercury Barometers

A mercury barometer consists of a glass A mercury barometer consists of a glass tube open at the bottom end and partially tube open at the bottom end and partially filled with mercury. The space at the top filled with mercury. The space at the top has no air, it’s a vacuum. The bottom end is has no air, it’s a vacuum. The bottom end is placed in a bowl of mercury.placed in a bowl of mercury.

Aneroid BarometersAneroid Barometers Aneroid barometerAneroid barometer – has an air tight metal – has an air tight metal

chamber. The metal chamber is sensitive to chamber. The metal chamber is sensitive to changes in air pressure. When air pressure changes in air pressure. When air pressure increases the walls of the chamber are increases the walls of the chamber are pushed in. When it decreases, they bulge pushed in. When it decreases, they bulge out. out.

These barometers are smaller and do not These barometers are smaller and do not contain any liquid.contain any liquid.

The UnitsThe Units

Most weather reports for the general public Most weather reports for the general public use inches of mercury. However, the use inches of mercury. However, the national weather service uses milibars.national weather service uses milibars.

-One inch is equal to 33.87 milibars-One inch is equal to 33.87 milibars

Increasing AltitudeIncreasing Altitude

Altitude, or elevation, is the distance above Altitude, or elevation, is the distance above sea level.sea level.

The higher the altitude, the lower the The higher the altitude, the lower the density. Sea-level altitude has the weight of density. Sea-level altitude has the weight of the whole atmosphere on it.the whole atmosphere on it.

The higher the altitude, the percentage of The higher the altitude, the percentage of oxygen goes down.oxygen goes down.

Increasing AltitudeIncreasing Altitude

Section 4- Layers of the atmosphereSection 4- Layers of the atmosphere

There are 4 main layers of the atmosphere:There are 4 main layers of the atmosphere:– TroposphereTroposphere– StratosphereStratosphere– MesosphereMesosphere– ThermosphereThermosphere

They are classified according to changes in They are classified according to changes in temperature. temperature.

TroposphereTroposphere

TropoTropo – turning or changing. – turning or changing. – 0-16 km above the equator.0-16 km above the equator.

The troposphere is where the Earth’s The troposphere is where the Earth’s weather occurs. weather occurs.

It is the shallowest layer of the atmosphere. It is the shallowest layer of the atmosphere. Contains almost all of the mass of the Contains almost all of the mass of the

atmosphere. atmosphere. As the altitude increases, temperature As the altitude increases, temperature

decreases. decreases.

StratosphereStratosphere

StratoStrato – layer or spreading out. – layer or spreading out.– 16-50km above the equator. 16-50km above the equator.

The lower part is about -60The lower part is about -60ooC while the C while the upper part is warmer because this is the upper part is warmer because this is the lower part of the ozone, the 3-atom form of lower part of the ozone, the 3-atom form of oxygen. oxygen.

The ozone layer absorbs energy from the The ozone layer absorbs energy from the sun.sun.

MesosphereMesosphere

MesoMeso – middle – middle– 50-80km above the earth.50-80km above the earth.

This layer is the coldest, -90This layer is the coldest, -90ooC. C. It protects the Earth from most meteoroids, It protects the Earth from most meteoroids,

what you see is a trail of hot, glowing gases.what you see is a trail of hot, glowing gases.

ThermosphereThermosphere

ThermoThermo – heat – heat– 80+km (no definite outer limit)80+km (no definite outer limit)

The air is very thin, about .001% than that of The air is very thin, about .001% than that of sea level. sea level.

Temperatures reach 1,800Temperatures reach 1,800ooC yet a C yet a thermometer will show below 0thermometer will show below 0ooC. Why?C. Why?– Molecules are spread out and don’t collide even Molecules are spread out and don’t collide even

though they are moving rapidly.though they are moving rapidly.

ThermosphereThermosphere

The thermosphere has two parts:The thermosphere has two parts:– IonosphereIonosphere - 80-550km where the aurora - 80-550km where the aurora

borealis (Northern Lights) takes place.borealis (Northern Lights) takes place.– ExosphereExosphere – 550 + km where phone and TV – 550 + km where phone and TV

signals bounce off satellites. signals bounce off satellites.