The Air Around You
• Weather: The condition of the Earth’s atmosphere at a particular time and place
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
• 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
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
• Aneroid Barometer
–Airtight metal chamber that senseschange in air pressure
The Effects of Altitude
• Air Pressure (INVERSE RELATIONSHIP)
–Increases as altitude decreases
–Decreases as altitudeincreases
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
• 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.
Stratosphere–Lower Layer cold
-60oC
–Middle layer Ozone
–Absorbs energyfrom the sun into heat
–Upper layer warmer
–Planes fly here
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)
Air Quality
• Air that contains harmful particles and gases is polluted– Pollutants: harmful substances in air, water,
or soil
Sources of Pollution
• Human activity
–farming and construction
–burning fossil fuels
•Cars and motor vehicles
•Factories and power plants
Effects of Pollution
• Acid Rain: air that contains more acid than normal
–damages surfaces of buildings and statues
–harms lakes and ponds