2 Chapter 1: Earth’s Changing Atmosphere 1.1 Earth’s Atmosphere Supports LifeAir – mixture of gasesAtmosphere – layer of air that surrounds the Earth1. Supports life and protects it2. Keeps Earth warm3. Transports energy
3 Characteristics of the Atmosphere Altitude – distance above sea levelThe thickness or thinness of air is measured by its density.Density – the amount of mass in a given volume of a substance*Atmosphere’s density decreases as you travel upward.
4 Gases in the atmosphere: Nitrogen (N2) – 78%Oxygen (O2) – 21%Carbon Dioxide (CO2), argon, other gases – 1%Nitrogen – promotes plant growthOxygen – animals and plants perform life processesCarbon dioxide – plants use to make food
5 Cycles – processes that are repeated over and over again 1. Carbon Cycle :a. Oxygen inhaled by animals, exhales Carbon Dioxide (CO2)b. CO2 taken in by plants, releases Oxygen (O2)2. Nitrogen Cycle :a. tiny organisms (living things) remove N2 from air, changes it into other chemicals and returns it to the soil.b. plants/animals use solids/liquids that contain N2, then return to soil when they die & decay.c. soil slowly releases N2 back in the air3. Water Cycle:a. Liquid water from oceans & lakes changes intogas (evaporates) and enters atmosphereb. Plants release water vapor from leavesc. Liquid water falls back to atmosphere asprecipitation – rain, snow, sleet, or hail.
6 Sudden Changes:**Volcanic eruptions, forest fires, dust storms can cause changes in the atmosphereVolcanic Eruptions – shoots gases and ash into the atmosphere.Forest Fires – when forests burn, carbon that makes up the trees enters the atmosphere as carbon dioxide.Dust Storms – Adds huge amounts of particles to the air.
7 Section 1.2: The Sun Supplies the Atmosphere’s Energy Two main things happen to sunlight when it hits the Earth:1. Sunlight is reflected – you see most objects by reflected sunlight2. Sunlight is absorbed – sand absorbs sunlight & becomes warm
8 The Atmosphere Moves Energy Processes that move Energy from place to place:Radiation - Energy that travels distances in waves, can be absorbed or reflected.Conduction – Transfer of heat energy from one substance to another by direct contact.Convection – Transfer of energy by the motion of gas or liquid. Movement of gases up and down. Warm air rises, cool air sinks.Example:1. Radiation from sun warms the sand2. Hot sand conducts energy to feet, air –oranything that touches the sand3. Warm air carries energy upward by convection
9 1.3 - Gases in the Atmosphere pgs. 22-25 Atmosphere effects light in 4 ways:Absorb lightReflect lightLet it pass throughGive off light – emit light
10 1.3 - Two types of radiation (energy): 1. Ultraviolet radiation – waves of energy you can’t see, causes sunburn.2. infrared radiation – warms the materials that absorb it.
11 1.3 - Earth’s Protection:Ozone layer – ozone gases in the stratosphere, protects life on earth by absorbing harmful ultraviolet rays from sun.Greenhouse effect – traps heat – absorbs gases (carbon dioxide, methane, etc.) and keeps earth warm – allows heat to go back into space.Keeps Earth’s average surface temp. around 59 degrees.
12 Air Masses 3.1 – pgsAir Mass – large body of air. covers thousands of miles.Characteristics of Air Mass: depends on where it forms and the temperature1st word tells where it forms (land or water)2nd word tells temp. (near or far from equator)
13 Four Types:Continental Tropical – dry and warmContinental Polar – dry and coolMaritime Tropical – moist and warmMaritime Polar – moist and coolAir Masses move from West to East – away from where they start.Takes on characteristics of earth’s surface as it moves.
14 Front – boundary between air masses. fronts are often cloudy or stormy3 types:Cold Front – cold air mass pushes a warm air mass. Produces cumulonimbus clouds. Brief heavy storms.Cool weatherWarm Front – warm air mass pushes cold air mass.Hours of rain or snow – warm airStationary Front – Two air masses push against each other and stop moving.Becomes warm or cold when one air mass advances.
15 Storms: 3.2 – 3.3 pgs. 87 – 97 Storms – 3.2High pressure system – can bring clear skies, calm air, gentle breezesLow Pressure system – brings stormy weatherTropical Storm – low pressure system that starts at the equator – winds 40 mph (65k)
16 Hurricanes Hurricane – low pressure system – winds 74 mph (120k) Hurricane strike between Aug. thru Oct. – when water gets warm enough – loses strength when reaches landEye of Hurricane – center of storm, calm winds
17 Storm Surge – pushes huge mass of ocean water onto coastal area. Winter storms result of two air masses colliding.NWS – National Weather Service – alerts people to dangerous weather.
18 Blizzards – Blinding snowstorms, winds 35mph, occur in northern and central U.S. Ice storms – rain falls onto freezing cold ground.covers everything with ice
19 Severe Storms – 3.3 Lightning – spark of electricity Air around lightning is heated briefly to temp. hotter than the surface of sunThunder – sharp wave of heated air that travels away from lightning
20 Thunderstorm – storm with lightning and thunder – get energy from humid air. Effects of Thunderstorms:Flash floods, winds, hail, lightningTornado – violently rotating column of air – occurs mostly in spring - unpredictable