Presentation on theme: "Earths Atmosphere. Chapter 1: Earth’s Changing Atmosphere 1.1 Earth’s Atmosphere Supports Life Air – mixture of gases Atmosphere – layer of air that surrounds."— Presentation transcript:
Chapter 1: Earth’s Changing Atmosphere 1.1 Earth’s Atmosphere Supports Life Air – mixture of gases Atmosphere – layer of air that surrounds the Earth 1. Supports life and protects it 2. Keeps Earth warm 3. Transports energy
Characteristics of the Atmosphere Altitude – distance above sea level The thickness or thinness of air is measured by its density. Density – the amount of mass in a given volume of a substance Density – the amount of mass in a given volume of a substance *Atmosphere’s density decreases as you travel upward.
Gases in the atmosphere: Nitrogen (N 2 ) – 78% Oxygen (O 2 ) – 21% Carbon Dioxide (CO 2 ), argon, other gases – 1% Nitrogen – promotes plant growth Oxygen – animals and plants perform life processes Carbon dioxide – plants use to make food
Cycles – processes that are repeated over and over again 1. Carbon Cycle : a. Oxygen inhaled by animals, exhales Carbon Dioxide (CO2) 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 air 3. Water Cycle: a. Liquid water from oceans & lakes changes into gas (evaporates) and enters atmosphere b. Plants release water vapor from leaves c. Liquid water falls back to atmosphere as precipitation – rain, snow, sleet, or hail.
Sudden Changes: **Volcanic eruptions, forest fires, dust storms can cause changes in the atmosphere Volcanic 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.
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 sunlight 1. Sunlight is reflected – you see most objects by reflected sunlight 2. Sunlight is absorbed – sand absorbs sunlight & becomes warm 2. Sunlight is absorbed – sand absorbs sunlight & becomes warm
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 sand 2. Hot sand conducts energy to feet, air –or anything that touches the sand 3. Warm air carries energy upward by convection
1.3 - Gases in the Atmosphere pgs Atmosphere effects light in 4 ways: Absorb light Reflect light Let it pass through Give off light – emit light
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.
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.
Air Masses 3.1 – pgs Air Mass – large body of air. covers thousands of miles. Characteristics of Air Mass: depends on where it forms and the temperature 1st word tells where it forms (land or water) 2nd word tells temp. (near or far from equator)
Four Types: Continental Tropical – dry and warm Continental Polar – dry and cool Maritime Tropical – moist and warm Maritime Polar – moist and cool Air Masses move from West to East – away from where they start. Takes on characteristics of earth’s surface as it moves.
Front – boundary between air masses. fronts are often cloudy or stormy 3 types: Cold Front – cold air mass pushes a warm air mass. Produces cumulonimbus clouds. Brief heavy storms. Cool weather Cool weather Warm Front – warm air mass pushes cold air mass. Hours of rain or snow – warm air Stationary Front – Two air masses push against each other and stop moving. Becomes warm or cold when one air mass advances.
Storms: 3.2 – 3.3 pgs. 87 – 97 Storms – 3.2 High pressure system – can bring clear skies, calm air, gentle breezes Low Pressure system – brings stormy weather Tropical Storm – low pressure system that starts at the equator – winds 40 mph (65k)
Hurricanes Hurricane – low pressure system – winds 74 mph (120k) Hurricane strike between Aug. thru Oct. – when water gets warm enough – loses strength when reaches land Eye of Hurricane – center of storm, calm winds
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.
Blizzards – Blinding snowstorms, winds 35mph, occur in northern and central U.S. Ice storms – rain falls onto freezing cold ground. covers everything with ice
Severe Storms – 3.3 Lightning – spark of electricity Air around lightning is heated briefly to temp. hotter than the surface of sun Thunder – sharp wave of heated air that travels away from lightning
Thunderstorm – storm with lightning and thunder – get energy from humid air. Effects of Thunderstorms: Flash floods, winds, hail, lightning Tornado – violently rotating column of air – occurs mostly in spring - unpredictable