Transcript Chapter 1: Earth`s Changing Atmosphere

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 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
*Atmosphere’s density decreases as you
travel upward.
Gases in the atmosphere:
Nitrogen (N2) – 78%
Oxygen (O2) – 21%
Carbon Dioxide (CO2), 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)

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:
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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
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. 22-25
 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. 79-82
 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
 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