Chapter 15

Atmosphere Notes

The Air Around You

• Weather: The condition of the Earth’s atmosphere at a particular time and place

The Air Around You

• Atmosphere: the envelope of gases that surround the planet

Composition of the

Atmosphere• The atmosphere is made up of a mixture of atoms and molecules of different elements

Composition of the

Atmosphere

• Nitrogen: Most Abundant Gas in the atmosphere

–78% of air we breathe

• Oxygen: 2nd most Abundant Gas

–21% of air

–Involved in important processes

•Plants and animals take it to live

•Fuels use it to burn

•Iron and steel form rust

Composition of the

Atmosphere

–Ozone: 3 oxygen atoms

•Protects earth from UV Rays

•Like an umbrella

Composition of the

Atmosphere

• Carbon Dioxide– Plants need it to produce food

• Photosynthesis–Animals give off CO2

(Carbon Dioxide)

Composition of the

Atmosphere

–Fuels like coal and gasoline releaseCO2 after burning

• Increase CO2 in the atmosphere: greenhouse effect

Composition of the

Atmosphere

• Trace Gases: Other gases are present in very small amounts

• Water Vapor: Water in the form of gas

–Always present in various amounts

Composition of the

Atmosphere

Importance of

Atmosphere

• Earth’s Atmosphere makes conditions right for life on Earth.

• Atmosphere has oxygen and other gases we need

Importance of

Atmosphere

• Atmosphere keeps temp. stable and keeps liquid H2O on earth

• It keeps meteoroids from hitting earth

Air Pressure

•Since Air has MASS it also has PRESSURE and DENSITY

Properties of Air

• Air Pressure: the weight of a column of air pressing or pushing down on an area

–Molecules in air push in all directions

Properties of Air

• Density: The more molecules in the air, the more dense it is

–More Dense has more air pressure

Tools for Measuring Air Pressure

• Mercury Barometer

–Uses Mercury

–Standard 76 mm mercury

Tools for Measuring Air Pressure

• Aneroid Barometer

–Airtight metal chamber that senseschange in air pressure

Tools for Measuring Air Pressure

• Units of Air Pressure

–Inches of Mercury

–Millibars

The Effects of Altitude

• Air Pressure (INVERSE RELATIONSHIP)

–Increases as altitude decreases

–Decreases as altitudeincreases

The Effects of Altitude

• Altitude (elevation): Distance above sea level

Effects of Altitude

• Density (INVERSE RELATIONSHIP)

–Increases as altitude decreases

–Decreases as altitude increases

Layers of the

Atmosphere

• 4 Layers of the Atmosphere

–Troposphere

–Stratosphere

–Mesosphere

–Thermosphere

Layers of the Atmosphere

They are classified by temperature

Layers of the Atmosphere

• Troposphere –Tropo- turning or changing

–Lowest layer of Atmosphere

–Weather occurs here

Troposphere• Temperature decreases as altitude increases

• Temperature stopsdecreasing at the top of the troposphere

• Weather forms thin feathery clouds of ice.

Layers of the Atmosphere

• Stratosphere

• Strato- spread out or layer

• 2nd layer of the atmosphere

Stratosphere–Lower Layer cold

-60oC

–Middle layer Ozone

–Absorbs energyfrom the sun into heat

–Upper layer warmer

–Planes fly here

Layers of the Atmosphere

• Mesosphere

• Meso- middle layer

Mesosphere

• Protects the earth

–from meteoroids

• Temperature drops

Layers of the Atmosphere

• Thermosphere

• Thermo- heat layer and outer most layer

• Very thin air

• 0.001 % as

dense as

sea level air

Thermosphere

• No definite outer limit

• Sunlight strikes this layer first

–Up to 1,800 oC

–Nitrogen and Oxygen convert

this energy into heat

Layers of the Atmosphere

• Divided into 2 layers

–Ionosphere

•Has electrically charged particles called ions

Ionosphere• Auroras occur here (in the Ionosphere)

–Caused by particles from the sun that enter the ionosphere near the poles Glow

–Aurora Borealis (Northern Lights)

–Aurora Australis (Southern Lights)

Layers of the Atmosphere

–Exosphere

• Exo- outer

• Edge of atmosphere before space

Air Quality

• Air that contains harmful particles and gases is polluted– Pollutants: harmful substances in air, water,

or soil

Sources of Pollution

• Natural Sources

–Forest fires

–Soil Erosion

–Dust storms

–Mold and pollen

Sources of Pollution

• Human activity

–farming and construction

–burning fossil fuels

•Cars and motor vehicles

•Factories and power plants

Effects of Pollution

• Smog

–Smoke and fog

Effects of Pollution

• Acid Rain: air that contains more acid than normal

–damages surfaces of buildings and statues

–harms lakes and ponds

Improving Air Quality

• Environment Protection Agency (EPA)

–Monitors air pollution in U.S.A.

• Air quality has improved over last 30 years